Merge github.com:grpc/grpc into minimal

54 files changed, 2020 insertions, 728 deletions

diff --git a/doc/environment_variables.md b/doc/environment_variables.md
index 513936d660..47efb3a1d8 100644
--- a/doc/environment_variables.md
+++ b/doc/environment_variables.md
@@ -55,6 +55,7 @@ some configuration as environment variables that can be set.
   - queue_timeout
   - server_channel - lightweight trace of significant server channel events
   - secure_endpoint - traces bytes flowing through encrypted channels
+  - timer - timers (alarms) in the grpc internals
   - transport_security - traces metadata about secure channel establishment
   - tcp - traces bytes in and out of a channel
 
diff --git a/include/grpc/impl/codegen/atm_gcc_atomic.h b/include/grpc/impl/codegen/atm_gcc_atomic.h
index a486258c77..d52975ce97 100644
--- a/include/grpc/impl/codegen/atm_gcc_atomic.h
+++ b/include/grpc/impl/codegen/atm_gcc_atomic.h
@@ -39,6 +39,7 @@
 #include <grpc/impl/codegen/port_platform.h>
 
 typedef intptr_t gpr_atm;
+#define GPR_ATM_MAX INTPTR_MAX
 
 #ifdef GPR_LOW_LEVEL_COUNTERS
 extern gpr_atm gpr_counter_atm_cas;
diff --git a/include/grpc/impl/codegen/atm_gcc_sync.h b/include/grpc/impl/codegen/atm_gcc_sync.h
index 946545a671..b537e48f0f 100644
--- a/include/grpc/impl/codegen/atm_gcc_sync.h
+++ b/include/grpc/impl/codegen/atm_gcc_sync.h
@@ -39,6 +39,7 @@
 #include <grpc/impl/codegen/port_platform.h>
 
 typedef intptr_t gpr_atm;
+#define GPR_ATM_MAX INTPTR_MAX
 
 #define GPR_ATM_COMPILE_BARRIER_() __asm__ __volatile__("" : : : "memory")
 
diff --git a/include/grpc/impl/codegen/atm_windows.h b/include/grpc/impl/codegen/atm_windows.h
index 0ab70b95c4..b8f63da758 100644
--- a/include/grpc/impl/codegen/atm_windows.h
+++ b/include/grpc/impl/codegen/atm_windows.h
@@ -38,6 +38,7 @@
 #include <grpc/impl/codegen/port_platform.h>
 
 typedef intptr_t gpr_atm;
+#define GPR_ATM_MAX INTPTR_MAX
 
 #define gpr_atm_full_barrier MemoryBarrier
 
diff --git a/include/grpc/impl/codegen/port_platform.h b/include/grpc/impl/codegen/port_platform.h
index 086394648f..d525083cd0 100644
--- a/include/grpc/impl/codegen/port_platform.h
+++ b/include/grpc/impl/codegen/port_platform.h
@@ -375,8 +375,10 @@ typedef unsigned __int64 uint64_t;
 #ifndef GRPC_MUST_USE_RESULT
 #if defined(__GNUC__) && !defined(__MINGW32__)
 #define GRPC_MUST_USE_RESULT __attribute__((warn_unused_result))
+#define GPR_ALIGN_STRUCT(n) __attribute__((aligned(n)))
 #else
 #define GRPC_MUST_USE_RESULT
+#define GPR_ALIGN_STRUCT(n)
 #endif
 #endif
 
diff --git a/include/grpc/support/tls.h b/include/grpc/support/tls.h
index a45e1f0a4d..5365449f0d 100644
--- a/include/grpc/support/tls.h
+++ b/include/grpc/support/tls.h
@@ -58,7 +58,7 @@
      gpr_tls_set(&foo, new_value);
 
    Accessing a thread local:
-     current_value = gpr_tls_get(&foo, value);
+     current_value = gpr_tls_get(&foo);
 
    ALL functions here may be implemented as macros. */
 
diff --git a/src/core/ext/census/grpc_filter.c b/src/core/ext/census/grpc_filter.c
index fc29dbd454..bcf59a4efe 100644
--- a/src/core/ext/census/grpc_filter.c
+++ b/src/core/ext/census/grpc_filter.c
@@ -74,17 +74,18 @@ static void extract_and_annotate_method_tag(grpc_metadata_batch *md,
 }
 
 static void client_mutate_op(grpc_call_element *elem,
-                             grpc_transport_stream_op *op) {
+                             grpc_transport_stream_op_batch *op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   if (op->send_initial_metadata) {
-    extract_and_annotate_method_tag(op->send_initial_metadata, calld, chand);
+    extract_and_annotate_method_tag(
+        op->payload->send_initial_metadata.send_initial_metadata, calld, chand);
   }
 }
 
 static void client_start_transport_op(grpc_exec_ctx *exec_ctx,
                                       grpc_call_element *elem,
-                                      grpc_transport_stream_op *op) {
+                                      grpc_transport_stream_op_batch *op) {
   client_mutate_op(elem, op);
   grpc_call_next_op(exec_ctx, elem, op);
 }
@@ -103,19 +104,22 @@ static void server_on_done_recv(grpc_exec_ctx *exec_ctx, void *ptr,
 }
 
 static void server_mutate_op(grpc_call_element *elem,
-                             grpc_transport_stream_op *op) {
+                             grpc_transport_stream_op_batch *op) {
   call_data *calld = elem->call_data;
   if (op->recv_initial_metadata) {
     /* substitute our callback for the op callback */
-    calld->recv_initial_metadata = op->recv_initial_metadata;
-    calld->on_done_recv = op->recv_initial_metadata_ready;
-    op->recv_initial_metadata_ready = &calld->finish_recv;
+    calld->recv_initial_metadata =
+        op->payload->recv_initial_metadata.recv_initial_metadata;
+    calld->on_done_recv =
+        op->payload->recv_initial_metadata.recv_initial_metadata_ready;
+    op->payload->recv_initial_metadata.recv_initial_metadata_ready =
+        &calld->finish_recv;
   }
 }
 
 static void server_start_transport_op(grpc_exec_ctx *exec_ctx,
                                       grpc_call_element *elem,
-                                      grpc_transport_stream_op *op) {
+                                      grpc_transport_stream_op_batch *op) {
   /* TODO(ctiller): this code fails. I don't know why. I expect it's
                     incomplete, and someone should look at it soon.
 
diff --git a/src/core/ext/filters/client_channel/client_channel.c b/src/core/ext/filters/client_channel/client_channel.c
index d289272489..93ad53aab9 100644
--- a/src/core/ext/filters/client_channel/client_channel.c
+++ b/src/core/ext/filters/client_channel/client_channel.c
@@ -532,7 +532,7 @@ static void on_resolver_result_changed_locked(grpc_exec_ctx *exec_ctx,
 static void start_transport_op_locked(grpc_exec_ctx *exec_ctx, void *arg,
                                       grpc_error *error_ignored) {
   grpc_transport_op *op = arg;
-  grpc_channel_element *elem = op->transport_private.args[0];
+  grpc_channel_element *elem = op->handler_private.extra_arg;
   channel_data *chand = elem->channel_data;
 
   if (op->on_connectivity_state_change != NULL) {
@@ -594,12 +594,12 @@ static void cc_start_transport_op(grpc_exec_ctx *exec_ctx,
                                  op->bind_pollset);
   }
 
-  op->transport_private.args[0] = elem;
+  op->handler_private.extra_arg = elem;
   GRPC_CHANNEL_STACK_REF(chand->owning_stack, "start_transport_op");
   grpc_closure_sched(
-      exec_ctx, grpc_closure_init(
-                    &op->transport_private.closure, start_transport_op_locked,
-                    op, grpc_combiner_scheduler(chand->combiner, false)),
+      exec_ctx,
+      grpc_closure_init(&op->handler_private.closure, start_transport_op_locked,
+                        op, grpc_combiner_scheduler(chand->combiner, false)),
       GRPC_ERROR_NONE);
 }
 
@@ -766,7 +766,7 @@ typedef struct client_channel_call_data {
   grpc_connected_subchannel *connected_subchannel;
   grpc_polling_entity *pollent;
 
-  grpc_transport_stream_op **waiting_ops;
+  grpc_transport_stream_op_batch **waiting_ops;
   size_t waiting_ops_count;
   size_t waiting_ops_capacity;
 
@@ -786,7 +786,8 @@ grpc_subchannel_call *grpc_client_channel_get_subchannel_call(
   return scc == CANCELLED_CALL ? NULL : scc;
 }
 
-static void add_waiting_locked(call_data *calld, grpc_transport_stream_op *op) {
+static void add_waiting_locked(call_data *calld,
+                               grpc_transport_stream_op_batch *op) {
   GPR_TIMER_BEGIN("add_waiting_locked", 0);
   if (calld->waiting_ops_count == calld->waiting_ops_capacity) {
     calld->waiting_ops_capacity = GPR_MAX(3, 2 * calld->waiting_ops_capacity);
@@ -802,7 +803,7 @@ static void fail_locked(grpc_exec_ctx *exec_ctx, call_data *calld,
                         grpc_error *error) {
   size_t i;
   for (i = 0; i < calld->waiting_ops_count; i++) {
-    grpc_transport_stream_op_finish_with_failure(
+    grpc_transport_stream_op_batch_finish_with_failure(
         exec_ctx, calld->waiting_ops[i], GRPC_ERROR_REF(error));
   }
   calld->waiting_ops_count = 0;
@@ -815,7 +816,7 @@ static void retry_waiting_locked(grpc_exec_ctx *exec_ctx, call_data *calld) {
   }
 
   grpc_subchannel_call *call = GET_CALL(calld);
-  grpc_transport_stream_op **ops = calld->waiting_ops;
+  grpc_transport_stream_op_batch **ops = calld->waiting_ops;
   size_t nops = calld->waiting_ops_count;
   if (call == CANCELLED_CALL) {
     fail_locked(exec_ctx, calld, GRPC_ERROR_CANCELLED);
@@ -1063,9 +1064,9 @@ static bool pick_subchannel_locked(
   return false;
 }
 
-static void start_transport_stream_op_locked_inner(grpc_exec_ctx *exec_ctx,
-                                                   grpc_transport_stream_op *op,
-                                                   grpc_call_element *elem) {
+static void start_transport_stream_op_batch_locked_inner(
+    grpc_exec_ctx *exec_ctx, grpc_transport_stream_op_batch *op,
+    grpc_call_element *elem) {
   channel_data *chand = elem->channel_data;
   call_data *calld = elem->call_data;
   grpc_subchannel_call *call;
@@ -1073,7 +1074,7 @@ static void start_transport_stream_op_locked_inner(grpc_exec_ctx *exec_ctx,
   /* need to recheck that another thread hasn't set the call */
   call = GET_CALL(calld);
   if (call == CANCELLED_CALL) {
-    grpc_transport_stream_op_finish_with_failure(
+    grpc_transport_stream_op_batch_finish_with_failure(
         exec_ctx, op, GRPC_ERROR_REF(calld->cancel_error));
     /* early out */
     return;
@@ -1084,11 +1085,11 @@ static void start_transport_stream_op_locked_inner(grpc_exec_ctx *exec_ctx,
     return;
   }
   /* if this is a cancellation, then we can raise our cancelled flag */
-  if (op->cancel_error != GRPC_ERROR_NONE) {
+  if (op->cancel_stream) {
     if (!gpr_atm_rel_cas(&calld->subchannel_call, 0,
                          (gpr_atm)(uintptr_t)CANCELLED_CALL)) {
       /* recurse to retry */
-      start_transport_stream_op_locked_inner(exec_ctx, op, elem);
+      start_transport_stream_op_batch_locked_inner(exec_ctx, op, elem);
       /* early out */
       return;
     } else {
@@ -1097,27 +1098,29 @@ static void start_transport_stream_op_locked_inner(grpc_exec_ctx *exec_ctx,
          cancelled before any ops are passed down (e.g., if the deadline
          is in the past when the call starts), we can return the right
          error to the caller when the first op does get passed down. */
-      calld->cancel_error = GRPC_ERROR_REF(op->cancel_error);
+      calld->cancel_error =
+          GRPC_ERROR_REF(op->payload->cancel_stream.cancel_error);
       switch (calld->creation_phase) {
         case GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING:
-          fail_locked(exec_ctx, calld, GRPC_ERROR_REF(op->cancel_error));
+          fail_locked(exec_ctx, calld,
+                      GRPC_ERROR_REF(op->payload->cancel_stream.cancel_error));
           break;
         case GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL:
-          pick_subchannel_locked(exec_ctx, elem, NULL, 0,
-                                 &calld->connected_subchannel, NULL,
-                                 GRPC_ERROR_REF(op->cancel_error));
+          pick_subchannel_locked(
+              exec_ctx, elem, NULL, 0, &calld->connected_subchannel, NULL,
+              GRPC_ERROR_REF(op->payload->cancel_stream.cancel_error));
           break;
       }
-      grpc_transport_stream_op_finish_with_failure(
-          exec_ctx, op, GRPC_ERROR_REF(op->cancel_error));
+      grpc_transport_stream_op_batch_finish_with_failure(
+          exec_ctx, op,
+          GRPC_ERROR_REF(op->payload->cancel_stream.cancel_error));
       /* early out */
       return;
     }
   }
   /* if we don't have a subchannel, try to get one */
   if (calld->creation_phase == GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING &&
-      calld->connected_subchannel == NULL &&
-      op->send_initial_metadata != NULL) {
+      calld->connected_subchannel == NULL && op->send_initial_metadata) {
     calld->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL;
     grpc_closure_init(&calld->next_step, subchannel_ready_locked, elem,
                       grpc_combiner_scheduler(chand->combiner, true));
@@ -1125,10 +1128,11 @@ static void start_transport_stream_op_locked_inner(grpc_exec_ctx *exec_ctx,
     /* If a subchannel is not available immediately, the polling entity from
        call_data should be provided to channel_data's interested_parties, so
        that IO of the lb_policy and resolver could be done under it. */
-    if (pick_subchannel_locked(exec_ctx, elem, op->send_initial_metadata,
-                               op->send_initial_metadata_flags,
-                               &calld->connected_subchannel, &calld->next_step,
-                               GRPC_ERROR_NONE)) {
+    if (pick_subchannel_locked(
+            exec_ctx, elem,
+            op->payload->send_initial_metadata.send_initial_metadata,
+            op->payload->send_initial_metadata.send_initial_metadata_flags,
+            &calld->connected_subchannel, &calld->next_step, GRPC_ERROR_NONE)) {
       calld->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
       GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call, "pick_subchannel");
     } else {
@@ -1151,13 +1155,13 @@ static void start_transport_stream_op_locked_inner(grpc_exec_ctx *exec_ctx,
     if (error != GRPC_ERROR_NONE) {
       subchannel_call = CANCELLED_CALL;
       fail_locked(exec_ctx, calld, GRPC_ERROR_REF(error));
-      grpc_transport_stream_op_finish_with_failure(exec_ctx, op, error);
+      grpc_transport_stream_op_batch_finish_with_failure(exec_ctx, op, error);
     }
     gpr_atm_rel_store(&calld->subchannel_call,
                       (gpr_atm)(uintptr_t)subchannel_call);
     retry_waiting_locked(exec_ctx, calld);
     /* recurse to retry */
-    start_transport_stream_op_locked_inner(exec_ctx, op, elem);
+    start_transport_stream_op_batch_locked_inner(exec_ctx, op, elem);
     /* early out */
     return;
   }
@@ -1185,15 +1189,16 @@ static void on_complete(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
                    GRPC_ERROR_REF(error));
 }
 
-static void start_transport_stream_op_locked(grpc_exec_ctx *exec_ctx, void *arg,
-                                             grpc_error *error_ignored) {
-  GPR_TIMER_BEGIN("start_transport_stream_op_locked", 0);
+static void start_transport_stream_op_batch_locked(grpc_exec_ctx *exec_ctx,
+                                                   void *arg,
+                                                   grpc_error *error_ignored) {
+  GPR_TIMER_BEGIN("start_transport_stream_op_batch_locked", 0);
 
-  grpc_transport_stream_op *op = arg;
-  grpc_call_element *elem = op->handler_private.args[0];
+  grpc_transport_stream_op_batch *op = arg;
+  grpc_call_element *elem = op->handler_private.extra_arg;
   call_data *calld = elem->call_data;
 
-  if (op->recv_trailing_metadata != NULL) {
+  if (op->recv_trailing_metadata) {
     GPR_ASSERT(op->on_complete != NULL);
     calld->original_on_complete = op->on_complete;
     grpc_closure_init(&calld->on_complete, on_complete, elem,
@@ -1201,11 +1206,11 @@ static void start_transport_stream_op_locked(grpc_exec_ctx *exec_ctx, void *arg,
     op->on_complete = &calld->on_complete;
   }
 
-  start_transport_stream_op_locked_inner(exec_ctx, op, elem);
+  start_transport_stream_op_batch_locked_inner(exec_ctx, op, elem);
 
   GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call,
-                        "start_transport_stream_op");
-  GPR_TIMER_END("start_transport_stream_op_locked", 0);
+                        "start_transport_stream_op_batch");
+  GPR_TIMER_END("start_transport_stream_op_batch_locked", 0);
 }
 
 /* The logic here is fairly complicated, due to (a) the fact that we
@@ -1216,39 +1221,40 @@ static void start_transport_stream_op_locked(grpc_exec_ctx *exec_ctx, void *arg,
    We use double-checked locking to initially see if initialization has been
    performed. If it has not, we acquire the combiner and perform initialization.
    If it has, we proceed on the fast path. */
-static void cc_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                         grpc_call_element *elem,
-                                         grpc_transport_stream_op *op) {
+static void cc_start_transport_stream_op_batch(
+    grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+    grpc_transport_stream_op_batch *op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
-  grpc_deadline_state_client_start_transport_stream_op(exec_ctx, elem, op);
+  grpc_deadline_state_client_start_transport_stream_op_batch(exec_ctx, elem,
+                                                             op);
   /* try to (atomically) get the call */
   grpc_subchannel_call *call = GET_CALL(calld);
-  GPR_TIMER_BEGIN("cc_start_transport_stream_op", 0);
+  GPR_TIMER_BEGIN("cc_start_transport_stream_op_batch", 0);
   if (call == CANCELLED_CALL) {
-    grpc_transport_stream_op_finish_with_failure(
+    grpc_transport_stream_op_batch_finish_with_failure(
         exec_ctx, op, GRPC_ERROR_REF(calld->cancel_error));
-    GPR_TIMER_END("cc_start_transport_stream_op", 0);
+    GPR_TIMER_END("cc_start_transport_stream_op_batch", 0);
     /* early out */
     return;
   }
   if (call != NULL) {
     grpc_subchannel_call_process_op(exec_ctx, call, op);
-    GPR_TIMER_END("cc_start_transport_stream_op", 0);
+    GPR_TIMER_END("cc_start_transport_stream_op_batch", 0);
     /* early out */
     return;
   }
   /* we failed; lock and figure out what to do */
-  GRPC_CALL_STACK_REF(calld->owning_call, "start_transport_stream_op");
-  op->handler_private.args[0] = elem;
+  GRPC_CALL_STACK_REF(calld->owning_call, "start_transport_stream_op_batch");
+  op->handler_private.extra_arg = elem;
   grpc_closure_sched(
       exec_ctx,
       grpc_closure_init(&op->handler_private.closure,
-                        start_transport_stream_op_locked, op,
+                        start_transport_stream_op_batch_locked, op,
                         grpc_combiner_scheduler(chand->combiner, false)),
       GRPC_ERROR_NONE);
-  GPR_TIMER_END("cc_start_transport_stream_op", 0);
+  GPR_TIMER_END("cc_start_transport_stream_op_batch", 0);
 }
 
 /* Constructor for call_data */
@@ -1307,7 +1313,7 @@ static void cc_set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,
  */
 
 const grpc_channel_filter grpc_client_channel_filter = {
-    cc_start_transport_stream_op,
+    cc_start_transport_stream_op_batch,
     cc_start_transport_op,
     sizeof(call_data),
     cc_init_call_elem,
diff --git a/src/core/ext/filters/client_channel/subchannel.c b/src/core/ext/filters/client_channel/subchannel.c
index dd3ca06239..8086cdb87e 100644
--- a/src/core/ext/filters/client_channel/subchannel.c
+++ b/src/core/ext/filters/client_channel/subchannel.c
@@ -748,11 +748,11 @@ char *grpc_subchannel_call_get_peer(grpc_exec_ctx *exec_ctx,
 
 void grpc_subchannel_call_process_op(grpc_exec_ctx *exec_ctx,
                                      grpc_subchannel_call *call,
-                                     grpc_transport_stream_op *op) {
+                                     grpc_transport_stream_op_batch *op) {
   GPR_TIMER_BEGIN("grpc_subchannel_call_process_op", 0);
   grpc_call_stack *call_stack = SUBCHANNEL_CALL_TO_CALL_STACK(call);
   grpc_call_element *top_elem = grpc_call_stack_element(call_stack, 0);
-  top_elem->filter->start_transport_stream_op(exec_ctx, top_elem, op);
+  top_elem->filter->start_transport_stream_op_batch(exec_ctx, top_elem, op);
   GPR_TIMER_END("grpc_subchannel_call_process_op", 0);
 }
 
diff --git a/src/core/ext/filters/client_channel/subchannel.h b/src/core/ext/filters/client_channel/subchannel.h
index 7a638e8b2e..6473de49b0 100644
--- a/src/core/ext/filters/client_channel/subchannel.h
+++ b/src/core/ext/filters/client_channel/subchannel.h
@@ -157,7 +157,7 @@ grpc_connected_subchannel *grpc_subchannel_get_connected_subchannel(
 /** continue processing a transport op */
 void grpc_subchannel_call_process_op(grpc_exec_ctx *exec_ctx,
                                      grpc_subchannel_call *subchannel_call,
-                                     grpc_transport_stream_op *op);
+                                     grpc_transport_stream_op_batch *op);
 
 /** continue querying for peer */
 char *grpc_subchannel_call_get_peer(grpc_exec_ctx *exec_ctx,
diff --git a/src/core/ext/filters/load_reporting/load_reporting_filter.c b/src/core/ext/filters/load_reporting/load_reporting_filter.c
index 7870ec0c4f..57b25d0651 100644
--- a/src/core/ext/filters/load_reporting/load_reporting_filter.c
+++ b/src/core/ext/filters/load_reporting/load_reporting_filter.c
@@ -183,25 +183,28 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   */
 }
 
-static void lr_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                         grpc_call_element *elem,
-                                         grpc_transport_stream_op *op) {
-  GPR_TIMER_BEGIN("lr_start_transport_stream_op", 0);
+static void lr_start_transport_stream_op_batch(
+    grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+    grpc_transport_stream_op_batch *op) {
+  GPR_TIMER_BEGIN("lr_start_transport_stream_op_batch", 0);
   call_data *calld = elem->call_data;
 
   if (op->recv_initial_metadata) {
-    calld->recv_initial_metadata = op->recv_initial_metadata;
+    calld->recv_initial_metadata =
+        op->payload->recv_initial_metadata.recv_initial_metadata;
     /* substitute our callback for the higher callback */
-    calld->ops_recv_initial_metadata_ready = op->recv_initial_metadata_ready;
-    op->recv_initial_metadata_ready = &calld->on_initial_md_ready;
+    calld->ops_recv_initial_metadata_ready =
+        op->payload->recv_initial_metadata.recv_initial_metadata_ready;
+    op->payload->recv_initial_metadata.recv_initial_metadata_ready =
+        &calld->on_initial_md_ready;
   }
   grpc_call_next_op(exec_ctx, elem, op);
 
-  GPR_TIMER_END("lr_start_transport_stream_op", 0);
+  GPR_TIMER_END("lr_start_transport_stream_op_batch", 0);
 }
 
 const grpc_channel_filter grpc_load_reporting_filter = {
-    lr_start_transport_stream_op,
+    lr_start_transport_stream_op_batch,
     grpc_channel_next_op,
     sizeof(call_data),
     init_call_elem,
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.c b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
index 26f9449f4b..a8e320d037 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.c
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
@@ -1140,20 +1140,23 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
                                      grpc_error *error_ignored) {
   GPR_TIMER_BEGIN("perform_stream_op_locked", 0);
 
-  grpc_transport_stream_op *op = stream_op;
-  grpc_chttp2_transport *t = op->handler_private.args[0];
-  grpc_chttp2_stream *s = op->handler_private.args[1];
+  grpc_transport_stream_op_batch *op = stream_op;
+  grpc_chttp2_stream *s = op->handler_private.extra_arg;
+  grpc_transport_stream_op_batch_payload *op_payload = op->payload;
+  grpc_chttp2_transport *t = s->t;
 
   if (grpc_http_trace) {
-    char *str = grpc_transport_stream_op_string(op);
+    char *str = grpc_transport_stream_op_batch_string(op);
     gpr_log(GPR_DEBUG, "perform_stream_op_locked: %s; on_complete = %p", str,
             op->on_complete);
     gpr_free(str);
     if (op->send_initial_metadata) {
-      log_metadata(op->send_initial_metadata, s->id, t->is_client, true);
+      log_metadata(op_payload->send_initial_metadata.send_initial_metadata,
+                   s->id, t->is_client, true);
     }
     if (op->send_trailing_metadata) {
-      log_metadata(op->send_trailing_metadata, s->id, t->is_client, false);
+      log_metadata(op_payload->send_trailing_metadata.send_trailing_metadata,
+                   s->id, t->is_client, false);
     }
   }
 
@@ -1168,23 +1171,25 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
   on_complete->next_data.scratch = CLOSURE_BARRIER_FIRST_REF_BIT;
   on_complete->error_data.error = GRPC_ERROR_NONE;
 
-  if (op->collect_stats != NULL) {
+  if (op->collect_stats) {
     GPR_ASSERT(s->collecting_stats == NULL);
-    s->collecting_stats = op->collect_stats;
+    s->collecting_stats = op_payload->collect_stats.collect_stats;
     on_complete->next_data.scratch |= CLOSURE_BARRIER_STATS_BIT;
   }
 
-  if (op->cancel_error != GRPC_ERROR_NONE) {
-    grpc_chttp2_cancel_stream(exec_ctx, t, s, op->cancel_error);
+  if (op->cancel_stream) {
+    grpc_chttp2_cancel_stream(exec_ctx, t, s,
+                              op_payload->cancel_stream.cancel_error);
   }
 
-  if (op->send_initial_metadata != NULL) {
+  if (op->send_initial_metadata) {
     GPR_ASSERT(s->send_initial_metadata_finished == NULL);
     on_complete->next_data.scratch |= CLOSURE_BARRIER_MAY_COVER_WRITE;
     s->send_initial_metadata_finished = add_closure_barrier(on_complete);
-    s->send_initial_metadata = op->send_initial_metadata;
+    s->send_initial_metadata =
+        op_payload->send_initial_metadata.send_initial_metadata;
     const size_t metadata_size =
-        grpc_metadata_batch_size(op->send_initial_metadata);
+        grpc_metadata_batch_size(s->send_initial_metadata);
     const size_t metadata_peer_limit =
         t->settings[GRPC_PEER_SETTINGS]
                    [GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE];
@@ -1205,7 +1210,7 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
                   GRPC_ERROR_INT_LIMIT, (intptr_t)metadata_peer_limit),
               GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_RESOURCE_EXHAUSTED));
     } else {
-      if (contains_non_ok_status(op->send_initial_metadata)) {
+      if (contains_non_ok_status(s->send_initial_metadata)) {
         s->seen_error = true;
       }
       if (!s->write_closed) {
@@ -1225,8 +1230,9 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
           GPR_ASSERT(s->id != 0);
           grpc_chttp2_stream_write_type write_type =
               GRPC_CHTTP2_STREAM_WRITE_INITIATE_COVERED;
-          if (op->send_message != NULL &&
-              (op->send_message->flags & GRPC_WRITE_BUFFER_HINT)) {
+          if (op->send_message &&
+              (op->payload->send_message.send_message->flags &
+               GRPC_WRITE_BUFFER_HINT)) {
             write_type = GRPC_CHTTP2_STREAM_WRITE_PIGGYBACK;
           }
           grpc_chttp2_become_writable(exec_ctx, t, s, write_type,
@@ -1244,7 +1250,7 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
     }
   }
 
-  if (op->send_message != NULL) {
+  if (op->send_message) {
     on_complete->next_data.scratch |= CLOSURE_BARRIER_MAY_COVER_WRITE;
     s->fetching_send_message_finished = add_closure_barrier(op->on_complete);
     if (s->write_closed) {
@@ -1258,14 +1264,14 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
       GPR_ASSERT(s->fetching_send_message == NULL);
       uint8_t *frame_hdr =
           grpc_slice_buffer_tiny_add(&s->flow_controlled_buffer, 5);
-      uint32_t flags = op->send_message->flags;
+      uint32_t flags = op_payload->send_message.send_message->flags;
       frame_hdr[0] = (flags & GRPC_WRITE_INTERNAL_COMPRESS) != 0;
-      size_t len = op->send_message->length;
+      size_t len = op_payload->send_message.send_message->length;
       frame_hdr[1] = (uint8_t)(len >> 24);
       frame_hdr[2] = (uint8_t)(len >> 16);
       frame_hdr[3] = (uint8_t)(len >> 8);
       frame_hdr[4] = (uint8_t)(len);
-      s->fetching_send_message = op->send_message;
+      s->fetching_send_message = op_payload->send_message.send_message;
       s->fetched_send_message_length = 0;
       s->next_message_end_offset = s->flow_controlled_bytes_written +
                                    (int64_t)s->flow_controlled_buffer.length +
@@ -1282,14 +1288,15 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
     }
   }
 
-  if (op->send_trailing_metadata != NULL) {
+  if (op->send_trailing_metadata) {
     GPR_ASSERT(s->send_trailing_metadata_finished == NULL);
     on_complete->next_data.scratch |= CLOSURE_BARRIER_MAY_COVER_WRITE;
     s->send_trailing_metadata_finished = add_closure_barrier(on_complete);
-    s->send_trailing_metadata = op->send_trailing_metadata;
+    s->send_trailing_metadata =
+        op_payload->send_trailing_metadata.send_trailing_metadata;
     s->write_buffering = false;
     const size_t metadata_size =
-        grpc_metadata_batch_size(op->send_trailing_metadata);
+        grpc_metadata_batch_size(s->send_trailing_metadata);
     const size_t metadata_peer_limit =
         t->settings[GRPC_PEER_SETTINGS]
                    [GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE];
@@ -1306,14 +1313,15 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
                   GRPC_ERROR_INT_LIMIT, (intptr_t)metadata_peer_limit),
               GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_RESOURCE_EXHAUSTED));
     } else {
-      if (contains_non_ok_status(op->send_trailing_metadata)) {
+      if (contains_non_ok_status(s->send_trailing_metadata)) {
         s->seen_error = true;
       }
       if (s->write_closed) {
         s->send_trailing_metadata = NULL;
         grpc_chttp2_complete_closure_step(
             exec_ctx, t, s, &s->send_trailing_metadata_finished,
-            grpc_metadata_batch_is_empty(op->send_trailing_metadata)
+            grpc_metadata_batch_is_empty(
+                op->payload->send_trailing_metadata.send_trailing_metadata)
                 ? GRPC_ERROR_NONE
                 : GRPC_ERROR_CREATE_FROM_STATIC_STRING(
                       "Attempt to send trailing metadata after "
@@ -1329,17 +1337,19 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
     }
   }
 
-  if (op->recv_initial_metadata != NULL) {
+  if (op->recv_initial_metadata) {
     GPR_ASSERT(s->recv_initial_metadata_ready == NULL);
-    s->recv_initial_metadata_ready = op->recv_initial_metadata_ready;
-    s->recv_initial_metadata = op->recv_initial_metadata;
+    s->recv_initial_metadata_ready =
+        op_payload->recv_initial_metadata.recv_initial_metadata_ready;
+    s->recv_initial_metadata =
+        op_payload->recv_initial_metadata.recv_initial_metadata;
     grpc_chttp2_maybe_complete_recv_initial_metadata(exec_ctx, t, s);
   }
 
-  if (op->recv_message != NULL) {
+  if (op->recv_message) {
     GPR_ASSERT(s->recv_message_ready == NULL);
-    s->recv_message_ready = op->recv_message_ready;
-    s->recv_message = op->recv_message;
+    s->recv_message_ready = op_payload->recv_message.recv_message_ready;
+    s->recv_message = op_payload->recv_message.recv_message;
     if (s->id != 0 &&
         (s->incoming_frames.head == NULL || s->incoming_frames.head->is_tail)) {
       incoming_byte_stream_update_flow_control(exec_ctx, t, s, 5, 0);
@@ -1347,10 +1357,11 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
     grpc_chttp2_maybe_complete_recv_message(exec_ctx, t, s);
   }
 
-  if (op->recv_trailing_metadata != NULL) {
+  if (op->recv_trailing_metadata) {
     GPR_ASSERT(s->recv_trailing_metadata_finished == NULL);
     s->recv_trailing_metadata_finished = add_closure_barrier(on_complete);
-    s->recv_trailing_metadata = op->recv_trailing_metadata;
+    s->recv_trailing_metadata =
+        op_payload->recv_trailing_metadata.recv_trailing_metadata;
     s->final_metadata_requested = true;
     grpc_chttp2_maybe_complete_recv_trailing_metadata(exec_ctx, t, s);
   }
@@ -1363,19 +1374,19 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
 }
 
 static void perform_stream_op(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
-                              grpc_stream *gs, grpc_transport_stream_op *op) {
+                              grpc_stream *gs,
+                              grpc_transport_stream_op_batch *op) {
   GPR_TIMER_BEGIN("perform_stream_op", 0);
   grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
   grpc_chttp2_stream *s = (grpc_chttp2_stream *)gs;
 
   if (grpc_http_trace) {
-    char *str = grpc_transport_stream_op_string(op);
+    char *str = grpc_transport_stream_op_batch_string(op);
     gpr_log(GPR_DEBUG, "perform_stream_op[s=%p/%d]: %s", s, s->id, str);
     gpr_free(str);
   }
 
-  op->handler_private.args[0] = gt;
-  op->handler_private.args[1] = gs;
+  op->handler_private.extra_arg = gs;
   GRPC_CHTTP2_STREAM_REF(s, "perform_stream_op");
   grpc_closure_sched(
       exec_ctx,
@@ -1452,7 +1463,7 @@ static void perform_transport_op_locked(grpc_exec_ctx *exec_ctx,
                                         void *stream_op,
                                         grpc_error *error_ignored) {
   grpc_transport_op *op = stream_op;
-  grpc_chttp2_transport *t = op->transport_private.args[0];
+  grpc_chttp2_transport *t = op->handler_private.extra_arg;
   grpc_error *close_transport = op->disconnect_with_error;
 
   if (op->on_connectivity_state_change != NULL) {
@@ -1498,10 +1509,10 @@ static void perform_transport_op(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
   grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
   char *msg = grpc_transport_op_string(op);
   gpr_free(msg);
-  op->transport_private.args[0] = gt;
+  op->handler_private.extra_arg = gt;
   GRPC_CHTTP2_REF_TRANSPORT(t, "transport_op");
   grpc_closure_sched(
-      exec_ctx, grpc_closure_init(&op->transport_private.closure,
+      exec_ctx, grpc_closure_init(&op->handler_private.closure,
                                   perform_transport_op_locked, op,
                                   grpc_combiner_scheduler(t->combiner, false)),
       GRPC_ERROR_NONE);
diff --git a/src/core/ext/transport/cronet/transport/cronet_transport.c b/src/core/ext/transport/cronet/transport/cronet_transport.c
index 952690eba7..9bd8914b98 100644
--- a/src/core/ext/transport/cronet/transport/cronet_transport.c
+++ b/src/core/ext/transport/cronet/transport/cronet_transport.c
@@ -172,7 +172,7 @@ struct op_state {
 };
 
 struct op_and_state {
-  grpc_transport_stream_op op;
+  grpc_transport_stream_op_batch op;
   struct op_state state;
   bool done;
   struct stream_obj *s;      /* Pointer back to the stream object */
@@ -187,7 +187,7 @@ struct op_storage {
 struct stream_obj {
   gpr_arena *arena;
   struct op_and_state *oas;
-  grpc_transport_stream_op *curr_op;
+  grpc_transport_stream_op_batch *curr_op;
   grpc_cronet_transport *curr_ct;
   grpc_stream *curr_gs;
   bidirectional_stream *cbs;
@@ -298,12 +298,13 @@ static grpc_error *make_error_with_desc(int error_code, const char *desc) {
 /*
   Add a new stream op to op storage.
 */
-static void add_to_storage(struct stream_obj *s, grpc_transport_stream_op *op) {
+static void add_to_storage(struct stream_obj *s,
+                           grpc_transport_stream_op_batch *op) {
   struct op_storage *storage = &s->storage;
   /* add new op at the beginning of the linked list. The memory is freed
   in remove_from_storage */
   struct op_and_state *new_op = gpr_malloc(sizeof(struct op_and_state));
-  memcpy(&new_op->op, op, sizeof(grpc_transport_stream_op));
+  memcpy(&new_op->op, op, sizeof(grpc_transport_stream_op_batch));
   memset(&new_op->state, 0, sizeof(new_op->state));
   new_op->s = s;
   new_op->done = false;
@@ -768,7 +769,7 @@ static bool header_has_authority(grpc_linked_mdelem *head) {
   Op Execution: Decide if one of the actions contained in the stream op can be
   executed. This is the heart of the state machine.
 */
-static bool op_can_be_run(grpc_transport_stream_op *curr_op,
+static bool op_can_be_run(grpc_transport_stream_op_batch *curr_op,
                           struct stream_obj *s, struct op_state *op_state,
                           enum e_op_id op_id) {
   struct op_state *stream_state = &s->state;
@@ -919,7 +920,7 @@ static bool op_can_be_run(grpc_transport_stream_op *curr_op,
 */
 static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
                                           struct op_and_state *oas) {
-  grpc_transport_stream_op *stream_op = &oas->op;
+  grpc_transport_stream_op_batch *stream_op = &oas->op;
   struct stream_obj *s = oas->s;
   grpc_cronet_transport *t = (grpc_cronet_transport *)s->curr_ct;
   struct op_state *stream_state = &s->state;
@@ -941,9 +942,10 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
     char *url = NULL;
     const char *method = "POST";
     s->header_array.headers = NULL;
-    convert_metadata_to_cronet_headers(
-        stream_op->send_initial_metadata->list.head, t->host, &url,
-        &s->header_array.headers, &s->header_array.count, &method);
+    convert_metadata_to_cronet_headers(stream_op->payload->send_initial_metadata
+                                           .send_initial_metadata->list.head,
+                                       t->host, &url, &s->header_array.headers,
+                                       &s->header_array.count, &method);
     s->header_array.capacity = s->header_array.count;
     CRONET_LOG(GPR_DEBUG, "bidirectional_stream_start(%p, %s)", s->cbs, url);
     bidirectional_stream_start(s->cbs, url, 0, method, &s->header_array, false);
@@ -971,8 +973,9 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
       grpc_slice_buffer write_slice_buffer;
       grpc_slice slice;
       grpc_slice_buffer_init(&write_slice_buffer);
-      grpc_byte_stream_next(NULL, stream_op->send_message, &slice,
-                            stream_op->send_message->length, NULL);
+      grpc_byte_stream_next(
+          NULL, stream_op->payload->send_message.send_message, &slice,
+          stream_op->payload->send_message.send_message->length, NULL);
       grpc_slice_buffer_add(&write_slice_buffer, slice);
       if (write_slice_buffer.count != 1) {
         /* Empty request not handled yet */
@@ -982,7 +985,8 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
       if (write_slice_buffer.count > 0) {
         size_t write_buffer_size;
         create_grpc_frame(&write_slice_buffer, &stream_state->ws.write_buffer,
-                          &write_buffer_size, stream_op->send_message->flags);
+                          &write_buffer_size,
+                          stream_op->payload->send_message.send_message->flags);
         CRONET_LOG(GPR_DEBUG, "bidirectional_stream_write (%p, %p)", s->cbs,
                    stream_state->ws.write_buffer);
         stream_state->state_callback_received[OP_SEND_MESSAGE] = false;
@@ -1029,20 +1033,28 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
                            OP_RECV_INITIAL_METADATA)) {
     CRONET_LOG(GPR_DEBUG, "running: %p  OP_RECV_INITIAL_METADATA", oas);
     if (stream_state->state_op_done[OP_CANCEL_ERROR]) {
-      grpc_closure_sched(exec_ctx, stream_op->recv_initial_metadata_ready,
-                         GRPC_ERROR_NONE);
+      grpc_closure_sched(
+          exec_ctx,
+          stream_op->payload->recv_initial_metadata.recv_initial_metadata_ready,
+          GRPC_ERROR_NONE);
     } else if (stream_state->state_callback_received[OP_FAILED]) {
-      grpc_closure_sched(exec_ctx, stream_op->recv_initial_metadata_ready,
-                         GRPC_ERROR_NONE);
+      grpc_closure_sched(
+          exec_ctx,
+          stream_op->payload->recv_initial_metadata.recv_initial_metadata_ready,
+          GRPC_ERROR_NONE);
     } else if (stream_state->state_op_done[OP_RECV_TRAILING_METADATA]) {
-      grpc_closure_sched(exec_ctx, stream_op->recv_initial_metadata_ready,
-                         GRPC_ERROR_NONE);
+      grpc_closure_sched(
+          exec_ctx,
+          stream_op->payload->recv_initial_metadata.recv_initial_metadata_ready,
+          GRPC_ERROR_NONE);
     } else {
       grpc_chttp2_incoming_metadata_buffer_publish(
           exec_ctx, &oas->s->state.rs.initial_metadata,
-          stream_op->recv_initial_metadata);
-      grpc_closure_sched(exec_ctx, stream_op->recv_initial_metadata_ready,
-                         GRPC_ERROR_NONE);
+          stream_op->payload->recv_initial_metadata.recv_initial_metadata);
+      grpc_closure_sched(
+          exec_ctx,
+          stream_op->payload->recv_initial_metadata.recv_initial_metadata_ready,
+          GRPC_ERROR_NONE);
     }
     stream_state->state_op_done[OP_RECV_INITIAL_METADATA] = true;
     result = ACTION_TAKEN_NO_CALLBACK;
@@ -1051,27 +1063,31 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
     CRONET_LOG(GPR_DEBUG, "running: %p  OP_RECV_MESSAGE", oas);
     if (stream_state->state_op_done[OP_CANCEL_ERROR]) {
       CRONET_LOG(GPR_DEBUG, "Stream is cancelled.");
-      grpc_closure_sched(exec_ctx, stream_op->recv_message_ready,
+      grpc_closure_sched(exec_ctx,
+                         stream_op->payload->recv_message.recv_message_ready,
                          GRPC_ERROR_NONE);
       stream_state->state_op_done[OP_RECV_MESSAGE] = true;
       result = ACTION_TAKEN_NO_CALLBACK;
     } else if (stream_state->state_callback_received[OP_FAILED]) {
       CRONET_LOG(GPR_DEBUG, "Stream failed.");
-      grpc_closure_sched(exec_ctx, stream_op->recv_message_ready,
+      grpc_closure_sched(exec_ctx,
+                         stream_op->payload->recv_message.recv_message_ready,
                          GRPC_ERROR_NONE);
       stream_state->state_op_done[OP_RECV_MESSAGE] = true;
       result = ACTION_TAKEN_NO_CALLBACK;
     } else if (stream_state->rs.read_stream_closed == true) {
       /* No more data will be received */
       CRONET_LOG(GPR_DEBUG, "read stream closed");
-      grpc_closure_sched(exec_ctx, stream_op->recv_message_ready,
+      grpc_closure_sched(exec_ctx,
+                         stream_op->payload->recv_message.recv_message_ready,
                          GRPC_ERROR_NONE);
       stream_state->state_op_done[OP_RECV_MESSAGE] = true;
       oas->state.state_op_done[OP_RECV_MESSAGE] = true;
       result = ACTION_TAKEN_NO_CALLBACK;
     } else if (stream_state->flush_read) {
       CRONET_LOG(GPR_DEBUG, "flush read");
-      grpc_closure_sched(exec_ctx, stream_op->recv_message_ready,
+      grpc_closure_sched(exec_ctx,
+                         stream_op->payload->recv_message.recv_message_ready,
                          GRPC_ERROR_NONE);
       stream_state->state_op_done[OP_RECV_MESSAGE] = true;
       oas->state.state_op_done[OP_RECV_MESSAGE] = true;
@@ -1110,8 +1126,9 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
           }
           *((grpc_byte_buffer **)stream_op->recv_message) =
               (grpc_byte_buffer *)&stream_state->rs.sbs;
-          grpc_closure_sched(exec_ctx, stream_op->recv_message_ready,
-                             GRPC_ERROR_NONE);
+          grpc_closure_sched(
+              exec_ctx, stream_op->payload->recv_message.recv_message_ready,
+              GRPC_ERROR_NONE);
           stream_state->state_op_done[OP_RECV_MESSAGE] = true;
           oas->state.state_op_done[OP_RECV_MESSAGE] = true;
 
@@ -1163,7 +1180,8 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
       }
       *((grpc_byte_buffer **)stream_op->recv_message) =
           (grpc_byte_buffer *)&stream_state->rs.sbs;
-      grpc_closure_sched(exec_ctx, stream_op->recv_message_ready,
+      grpc_closure_sched(exec_ctx,
+                         stream_op->payload->recv_message.recv_message_ready,
                          GRPC_ERROR_NONE);
       stream_state->state_op_done[OP_RECV_MESSAGE] = true;
       oas->state.state_op_done[OP_RECV_MESSAGE] = true;
@@ -1187,12 +1205,12 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
     if (oas->s->state.rs.trailing_metadata_valid) {
       grpc_chttp2_incoming_metadata_buffer_publish(
           exec_ctx, &oas->s->state.rs.trailing_metadata,
-          stream_op->recv_trailing_metadata);
+          stream_op->payload->recv_trailing_metadata.recv_trailing_metadata);
       stream_state->rs.trailing_metadata_valid = false;
     }
     stream_state->state_op_done[OP_RECV_TRAILING_METADATA] = true;
     result = ACTION_TAKEN_NO_CALLBACK;
-  } else if (stream_op->cancel_error &&
+  } else if (stream_op->cancel_stream &&
              op_can_be_run(stream_op, s, &oas->state, OP_CANCEL_ERROR)) {
     CRONET_LOG(GPR_DEBUG, "running: %p  OP_CANCEL_ERROR", oas);
     CRONET_LOG(GPR_DEBUG, "W: bidirectional_stream_cancel(%p)", s->cbs);
@@ -1204,7 +1222,8 @@ static enum e_op_result execute_stream_op(grpc_exec_ctx *exec_ctx,
     }
     stream_state->state_op_done[OP_CANCEL_ERROR] = true;
     if (!stream_state->cancel_error) {
-      stream_state->cancel_error = GRPC_ERROR_REF(stream_op->cancel_error);
+      stream_state->cancel_error =
+          GRPC_ERROR_REF(stream_op->payload->cancel_stream.cancel_error);
     }
   } else if (stream_op->on_complete &&
              op_can_be_run(stream_op, s, &oas->state, OP_ON_COMPLETE)) {
@@ -1283,18 +1302,22 @@ static void set_pollset_set_do_nothing(grpc_exec_ctx *exec_ctx,
                                        grpc_pollset_set *pollset_set) {}
 
 static void perform_stream_op(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
-                              grpc_stream *gs, grpc_transport_stream_op *op) {
+                              grpc_stream *gs,
+                              grpc_transport_stream_op_batch *op) {
   CRONET_LOG(GPR_DEBUG, "perform_stream_op");
   if (op->send_initial_metadata &&
-      header_has_authority(op->send_initial_metadata->list.head)) {
+      header_has_authority(op->payload->send_initial_metadata
+                               .send_initial_metadata->list.head)) {
     /* Cronet does not support :authority header field. We cancel the call when
      this field is present in metadata */
-    if (op->recv_initial_metadata_ready) {
-      grpc_closure_sched(exec_ctx, op->recv_initial_metadata_ready,
-                         GRPC_ERROR_CANCELLED);
+    if (op->recv_initial_metadata) {
+      grpc_closure_sched(
+          exec_ctx,
+          op->payload->recv_initial_metadata.recv_initial_metadata_ready,
+          GRPC_ERROR_CANCELLED);
     }
-    if (op->recv_message_ready) {
-      grpc_closure_sched(exec_ctx, op->recv_message_ready,
+    if (op->recv_message) {
+      grpc_closure_sched(exec_ctx, op->payload->recv_message.recv_message_ready,
                          GRPC_ERROR_CANCELLED);
     }
     grpc_closure_sched(exec_ctx, op->on_complete, GRPC_ERROR_CANCELLED);
diff --git a/src/core/lib/channel/channel_stack.c b/src/core/lib/channel/channel_stack.c
index 6d53b0576e..94382980eb 100644
--- a/src/core/lib/channel/channel_stack.c
+++ b/src/core/lib/channel/channel_stack.c
@@ -246,9 +246,9 @@ void grpc_call_stack_destroy(grpc_exec_ctx *exec_ctx, grpc_call_stack *stack,
 }
 
 void grpc_call_next_op(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                       grpc_transport_stream_op *op) {
+                       grpc_transport_stream_op_batch *op) {
   grpc_call_element *next_elem = elem + 1;
-  next_elem->filter->start_transport_stream_op(exec_ctx, next_elem, op);
+  next_elem->filter->start_transport_stream_op_batch(exec_ctx, next_elem, op);
 }
 
 char *grpc_call_next_get_peer(grpc_exec_ctx *exec_ctx,
@@ -284,7 +284,8 @@ grpc_call_stack *grpc_call_stack_from_top_element(grpc_call_element *elem) {
 void grpc_call_element_signal_error(grpc_exec_ctx *exec_ctx,
                                     grpc_call_element *elem,
                                     grpc_error *error) {
-  grpc_transport_stream_op *op = grpc_make_transport_stream_op(NULL);
-  op->cancel_error = error;
-  elem->filter->start_transport_stream_op(exec_ctx, elem, op);
+  grpc_transport_stream_op_batch *op = grpc_make_transport_stream_op(NULL);
+  op->cancel_stream = true;
+  op->payload->cancel_stream.cancel_error = error;
+  elem->filter->start_transport_stream_op_batch(exec_ctx, elem, op);
 }
diff --git a/src/core/lib/channel/channel_stack.h b/src/core/lib/channel/channel_stack.h
index 80e3603e8d..fdbcbdb018 100644
--- a/src/core/lib/channel/channel_stack.h
+++ b/src/core/lib/channel/channel_stack.h
@@ -112,9 +112,9 @@ typedef struct {
 typedef struct {
   /* Called to eg. send/receive data on a call.
      See grpc_call_next_op on how to call the next element in the stack */
-  void (*start_transport_stream_op)(grpc_exec_ctx *exec_ctx,
-                                    grpc_call_element *elem,
-                                    grpc_transport_stream_op *op);
+  void (*start_transport_stream_op_batch)(grpc_exec_ctx *exec_ctx,
+                                          grpc_call_element *elem,
+                                          grpc_transport_stream_op_batch *op);
   /* Called to handle channel level operations - e.g. new calls, or transport
      closure.
      See grpc_channel_next_op on how to call the next element in the stack */
@@ -281,7 +281,7 @@ void grpc_call_stack_ignore_set_pollset_or_pollset_set(
     grpc_polling_entity *pollent);
 /* Call the next operation in a call stack */
 void grpc_call_next_op(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                       grpc_transport_stream_op *op);
+                       grpc_transport_stream_op_batch *op);
 /* Call the next operation (depending on call directionality) in a channel
    stack */
 void grpc_channel_next_op(grpc_exec_ctx *exec_ctx, grpc_channel_element *elem,
@@ -300,7 +300,8 @@ grpc_channel_stack *grpc_channel_stack_from_top_element(
 grpc_call_stack *grpc_call_stack_from_top_element(grpc_call_element *elem);
 
 void grpc_call_log_op(char *file, int line, gpr_log_severity severity,
-                      grpc_call_element *elem, grpc_transport_stream_op *op);
+                      grpc_call_element *elem,
+                      grpc_transport_stream_op_batch *op);
 
 void grpc_call_element_signal_error(grpc_exec_ctx *exec_ctx,
                                     grpc_call_element *cur_elem,
diff --git a/src/core/lib/channel/compress_filter.c b/src/core/lib/channel/compress_filter.c
index 02dc479f3a..4625cba0d2 100644
--- a/src/core/lib/channel/compress_filter.c
+++ b/src/core/lib/channel/compress_filter.c
@@ -62,7 +62,7 @@ typedef struct call_data {
   /** If true, contents of \a compression_algorithm are authoritative */
   int has_compression_algorithm;
 
-  grpc_transport_stream_op *send_op;
+  grpc_transport_stream_op_batch *send_op;
   uint32_t send_length;
   uint32_t send_flags;
   grpc_slice incoming_slice;
@@ -210,7 +210,8 @@ static void finish_send_message(grpc_exec_ctx *exec_ctx,
 
   grpc_slice_buffer_stream_init(&calld->replacement_stream, &calld->slices,
                                 calld->send_flags);
-  calld->send_op->send_message = &calld->replacement_stream.base;
+  calld->send_op->payload->send_message.send_message =
+      &calld->replacement_stream.base;
   calld->post_send = calld->send_op->on_complete;
   calld->send_op->on_complete = &calld->send_done;
 
@@ -231,9 +232,9 @@ static void got_slice(grpc_exec_ctx *exec_ctx, void *elemp, grpc_error *error) {
 static void continue_send_message(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem) {
   call_data *calld = elem->call_data;
-  while (grpc_byte_stream_next(exec_ctx, calld->send_op->send_message,
-                               &calld->incoming_slice, ~(size_t)0,
-                               &calld->got_slice)) {
+  while (grpc_byte_stream_next(
+      exec_ctx, calld->send_op->payload->send_message.send_message,
+      &calld->incoming_slice, ~(size_t)0, &calld->got_slice)) {
     grpc_slice_buffer_add(&calld->slices, calld->incoming_slice);
     if (calld->send_length == calld->slices.length) {
       finish_send_message(exec_ctx, elem);
@@ -242,33 +243,34 @@ static void continue_send_message(grpc_exec_ctx *exec_ctx,
   }
 }
 
-static void compress_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                               grpc_call_element *elem,
-                                               grpc_transport_stream_op *op) {
+static void compress_start_transport_stream_op_batch(
+    grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+    grpc_transport_stream_op_batch *op) {
   call_data *calld = elem->call_data;
 
-  GPR_TIMER_BEGIN("compress_start_transport_stream_op", 0);
+  GPR_TIMER_BEGIN("compress_start_transport_stream_op_batch", 0);
 
   if (op->send_initial_metadata) {
     grpc_error *error = process_send_initial_metadata(
-        exec_ctx, elem, op->send_initial_metadata);
+        exec_ctx, elem,
+        op->payload->send_initial_metadata.send_initial_metadata);
     if (error != GRPC_ERROR_NONE) {
-      grpc_transport_stream_op_finish_with_failure(exec_ctx, op, error);
+      grpc_transport_stream_op_batch_finish_with_failure(exec_ctx, op, error);
       return;
     }
   }
-  if (op->send_message != NULL &&
-      !skip_compression(elem, op->send_message->flags)) {
+  if (op->send_message &&
+      !skip_compression(elem, op->payload->send_message.send_message->flags)) {
     calld->send_op = op;
-    calld->send_length = op->send_message->length;
-    calld->send_flags = op->send_message->flags;
+    calld->send_length = op->payload->send_message.send_message->length;
+    calld->send_flags = op->payload->send_message.send_message->flags;
     continue_send_message(exec_ctx, elem);
   } else {
     /* pass control down the stack */
     grpc_call_next_op(exec_ctx, elem, op);
   }
 
-  GPR_TIMER_END("compress_start_transport_stream_op", 0);
+  GPR_TIMER_END("compress_start_transport_stream_op_batch", 0);
 }
 
 /* Constructor for call_data */
@@ -337,7 +339,7 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {}
 
 const grpc_channel_filter grpc_compress_filter = {
-    compress_start_transport_stream_op,
+    compress_start_transport_stream_op_batch,
     grpc_channel_next_op,
     sizeof(call_data),
     init_call_elem,
diff --git a/src/core/lib/channel/connected_channel.c b/src/core/lib/channel/connected_channel.c
index 75c68a5534..22caf24373 100644
--- a/src/core/lib/channel/connected_channel.c
+++ b/src/core/lib/channel/connected_channel.c
@@ -62,9 +62,9 @@ typedef struct connected_channel_call_data { void *unused; } call_data;
 
 /* Intercept a call operation and either push it directly up or translate it
    into transport stream operations */
-static void con_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                          grpc_call_element *elem,
-                                          grpc_transport_stream_op *op) {
+static void con_start_transport_stream_op_batch(
+    grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+    grpc_transport_stream_op_batch *op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
@@ -142,7 +142,7 @@ static void con_get_channel_info(grpc_exec_ctx *exec_ctx,
                                  const grpc_channel_info *channel_info) {}
 
 const grpc_channel_filter grpc_connected_filter = {
-    con_start_transport_stream_op,
+    con_start_transport_stream_op_batch,
     con_start_transport_op,
     sizeof(call_data),
     init_call_elem,
diff --git a/src/core/lib/channel/deadline_filter.c b/src/core/lib/channel/deadline_filter.c
index ca701ed457..fda099b021 100644
--- a/src/core/lib/channel/deadline_filter.c
+++ b/src/core/lib/channel/deadline_filter.c
@@ -134,7 +134,7 @@ static void on_complete(grpc_exec_ctx* exec_ctx, void* arg, grpc_error* error) {
 
 // Inject our own on_complete callback into op.
 static void inject_on_complete_cb(grpc_deadline_state* deadline_state,
-                                  grpc_transport_stream_op* op) {
+                                  grpc_transport_stream_op_batch* op) {
   deadline_state->next_on_complete = op->on_complete;
   grpc_closure_init(&deadline_state->on_complete, on_complete, deadline_state,
                     grpc_schedule_on_exec_ctx);
@@ -196,16 +196,16 @@ void grpc_deadline_state_reset(grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
   start_timer_if_needed(exec_ctx, elem, new_deadline);
 }
 
-void grpc_deadline_state_client_start_transport_stream_op(
+void grpc_deadline_state_client_start_transport_stream_op_batch(
     grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
-    grpc_transport_stream_op* op) {
+    grpc_transport_stream_op_batch* op) {
   grpc_deadline_state* deadline_state = elem->call_data;
-  if (op->cancel_error != GRPC_ERROR_NONE) {
+  if (op->cancel_stream) {
     cancel_timer_if_needed(exec_ctx, deadline_state);
   } else {
     // Make sure we know when the call is complete, so that we can cancel
     // the timer.
-    if (op->recv_trailing_metadata != NULL) {
+    if (op->recv_trailing_metadata) {
       inject_on_complete_cb(deadline_state, op);
     }
   }
@@ -261,10 +261,11 @@ static void destroy_call_elem(grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
 }
 
 // Method for starting a call op for client filter.
-static void client_start_transport_stream_op(grpc_exec_ctx* exec_ctx,
-                                             grpc_call_element* elem,
-                                             grpc_transport_stream_op* op) {
-  grpc_deadline_state_client_start_transport_stream_op(exec_ctx, elem, op);
+static void client_start_transport_stream_op_batch(
+    grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
+    grpc_transport_stream_op_batch* op) {
+  grpc_deadline_state_client_start_transport_stream_op_batch(exec_ctx, elem,
+                                                             op);
   // Chain to next filter.
   grpc_call_next_op(exec_ctx, elem, op);
 }
@@ -282,30 +283,33 @@ static void recv_initial_metadata_ready(grpc_exec_ctx* exec_ctx, void* arg,
 }
 
 // Method for starting a call op for server filter.
-static void server_start_transport_stream_op(grpc_exec_ctx* exec_ctx,
-                                             grpc_call_element* elem,
-                                             grpc_transport_stream_op* op) {
+static void server_start_transport_stream_op_batch(
+    grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
+    grpc_transport_stream_op_batch* op) {
   server_call_data* calld = elem->call_data;
-  if (op->cancel_error != GRPC_ERROR_NONE) {
+  if (op->cancel_stream) {
     cancel_timer_if_needed(exec_ctx, &calld->base.deadline_state);
   } else {
     // If we're receiving initial metadata, we need to get the deadline
     // from the recv_initial_metadata_ready callback.  So we inject our
     // own callback into that hook.
-    if (op->recv_initial_metadata_ready != NULL) {
-      calld->next_recv_initial_metadata_ready = op->recv_initial_metadata_ready;
-      calld->recv_initial_metadata = op->recv_initial_metadata;
+    if (op->recv_initial_metadata) {
+      calld->next_recv_initial_metadata_ready =
+          op->payload->recv_initial_metadata.recv_initial_metadata_ready;
+      calld->recv_initial_metadata =
+          op->payload->recv_initial_metadata.recv_initial_metadata;
       grpc_closure_init(&calld->recv_initial_metadata_ready,
                         recv_initial_metadata_ready, elem,
                         grpc_schedule_on_exec_ctx);
-      op->recv_initial_metadata_ready = &calld->recv_initial_metadata_ready;
+      op->payload->recv_initial_metadata.recv_initial_metadata_ready =
+          &calld->recv_initial_metadata_ready;
     }
     // Make sure we know when the call is complete, so that we can cancel
     // the timer.
     // Note that we trigger this on recv_trailing_metadata, even though
     // the client never sends trailing metadata, because this is the
     // hook that tells us when the call is complete on the server side.
-    if (op->recv_trailing_metadata != NULL) {
+    if (op->recv_trailing_metadata) {
       inject_on_complete_cb(&calld->base.deadline_state, op);
     }
   }
@@ -314,7 +318,7 @@ static void server_start_transport_stream_op(grpc_exec_ctx* exec_ctx,
 }
 
 const grpc_channel_filter grpc_client_deadline_filter = {
-    client_start_transport_stream_op,
+    client_start_transport_stream_op_batch,
     grpc_channel_next_op,
     sizeof(base_call_data),
     init_call_elem,
@@ -329,7 +333,7 @@ const grpc_channel_filter grpc_client_deadline_filter = {
 };
 
 const grpc_channel_filter grpc_server_deadline_filter = {
-    server_start_transport_stream_op,
+    server_start_transport_stream_op_batch,
     grpc_channel_next_op,
     sizeof(server_call_data),
     init_call_elem,
diff --git a/src/core/lib/channel/deadline_filter.h b/src/core/lib/channel/deadline_filter.h
index 72cd5cb929..d8db9a9f97 100644
--- a/src/core/lib/channel/deadline_filter.h
+++ b/src/core/lib/channel/deadline_filter.h
@@ -83,15 +83,15 @@ void grpc_deadline_state_start(grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
 void grpc_deadline_state_reset(grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
                                gpr_timespec new_deadline);
 
-// To be called from the client-side filter's start_transport_stream_op()
+// To be called from the client-side filter's start_transport_stream_op_batch()
 // method.  Ensures that the deadline timer is cancelled when the call
 // is completed.
 //
 // Note: It is the caller's responsibility to chain to the next filter if
 // necessary after this function returns.
-void grpc_deadline_state_client_start_transport_stream_op(
+void grpc_deadline_state_client_start_transport_stream_op_batch(
     grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
-    grpc_transport_stream_op* op);
+    grpc_transport_stream_op_batch* op);
 
 // Deadline filters for direct client channels and server channels.
 // Note: Deadlines for non-direct client channels are handled by the
diff --git a/src/core/lib/channel/http_client_filter.c b/src/core/lib/channel/http_client_filter.c
index 17af2013d9..4e47c5c658 100644
--- a/src/core/lib/channel/http_client_filter.c
+++ b/src/core/lib/channel/http_client_filter.c
@@ -63,7 +63,7 @@ typedef struct call_data {
   uint8_t *payload_bytes;
 
   /* Vars to read data off of send_message */
-  grpc_transport_stream_op send_op;
+  grpc_transport_stream_op_batch *send_op;
   uint32_t send_length;
   uint32_t send_flags;
   grpc_slice incoming_slice;
@@ -219,9 +219,9 @@ static void continue_send_message(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem) {
   call_data *calld = elem->call_data;
   uint8_t *wrptr = calld->payload_bytes;
-  while (grpc_byte_stream_next(exec_ctx, calld->send_op.send_message,
-                               &calld->incoming_slice, ~(size_t)0,
-                               &calld->got_slice)) {
+  while (grpc_byte_stream_next(
+      exec_ctx, calld->send_op->payload->send_message.send_message,
+      &calld->incoming_slice, ~(size_t)0, &calld->got_slice)) {
     memcpy(wrptr, GRPC_SLICE_START_PTR(calld->incoming_slice),
            GRPC_SLICE_LENGTH(calld->incoming_slice));
     wrptr += GRPC_SLICE_LENGTH(calld->incoming_slice);
@@ -242,10 +242,11 @@ static void got_slice(grpc_exec_ctx *exec_ctx, void *elemp, grpc_error *error) {
     /* Pass down the original send_message op that was blocked.*/
     grpc_slice_buffer_stream_init(&calld->replacement_stream, &calld->slices,
                                   calld->send_flags);
-    calld->send_op.send_message = &calld->replacement_stream.base;
-    calld->post_send = calld->send_op.on_complete;
-    calld->send_op.on_complete = &calld->send_done;
-    grpc_call_next_op(exec_ctx, elem, &calld->send_op);
+    calld->send_op->payload->send_message.send_message =
+        &calld->replacement_stream.base;
+    calld->post_send = calld->send_op->on_complete;
+    calld->send_op->on_complete = &calld->send_done;
+    grpc_call_next_op(exec_ctx, elem, calld->send_op);
   } else {
     continue_send_message(exec_ctx, elem);
   }
@@ -253,29 +254,30 @@ static void got_slice(grpc_exec_ctx *exec_ctx, void *elemp, grpc_error *error) {
 
 static grpc_error *hc_mutate_op(grpc_exec_ctx *exec_ctx,
                                 grpc_call_element *elem,
-                                grpc_transport_stream_op *op) {
+                                grpc_transport_stream_op_batch *op) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
   grpc_error *error;
 
-  if (op->send_initial_metadata != NULL) {
+  if (op->send_initial_metadata) {
     /* Decide which HTTP VERB to use. We use GET if the request is marked
     cacheable, and the operation contains both initial metadata and send
     message, and the payload is below the size threshold, and all the data
     for this request is immediately available. */
     grpc_mdelem method = GRPC_MDELEM_METHOD_POST;
-    if ((op->send_initial_metadata_flags &
+    if (op->send_message &&
+        (op->payload->send_initial_metadata.send_initial_metadata_flags &
          GRPC_INITIAL_METADATA_CACHEABLE_REQUEST) &&
-        op->send_message != NULL &&
-        op->send_message->length < channeld->max_payload_size_for_get) {
+        op->payload->send_message.send_message->length <
+            channeld->max_payload_size_for_get) {
       method = GRPC_MDELEM_METHOD_GET;
       /* The following write to calld->send_message_blocked isn't racy with
       reads in hc_start_transport_op (which deals with SEND_MESSAGE ops) because
       being here means ops->send_message is not NULL, which is primarily
       guarding the read there. */
       calld->send_message_blocked = true;
-    } else if (op->send_initial_metadata_flags &
+    } else if (op->payload->send_initial_metadata.send_initial_metadata_flags &
                GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST) {
       method = GRPC_MDELEM_METHOD_PUT;
     }
@@ -283,12 +285,13 @@ static grpc_error *hc_mutate_op(grpc_exec_ctx *exec_ctx,
     /* Attempt to read the data from send_message and create a header field. */
     if (grpc_mdelem_eq(method, GRPC_MDELEM_METHOD_GET)) {
       /* allocate memory to hold the entire payload */
-      calld->payload_bytes = gpr_malloc(op->send_message->length);
+      calld->payload_bytes =
+          gpr_malloc(op->payload->send_message.send_message->length);
 
       /* read slices of send_message and copy into payload_bytes */
-      calld->send_op = *op;
-      calld->send_length = op->send_message->length;
-      calld->send_flags = op->send_message->flags;
+      calld->send_op = op;
+      calld->send_length = op->payload->send_message.send_message->length;
+      calld->send_flags = op->payload->send_message.send_message->flags;
       continue_send_message(exec_ctx, elem);
 
       if (calld->send_message_blocked == false) {
@@ -299,13 +302,15 @@ static grpc_error *hc_mutate_op(grpc_exec_ctx *exec_ctx,
         const unsigned char k_query_separator = '?';
 
         grpc_slice path_slice =
-            GRPC_MDVALUE(op->send_initial_metadata->idx.named.path->md);
+            GRPC_MDVALUE(op->payload->send_initial_metadata
+                             .send_initial_metadata->idx.named.path->md);
         /* sum up individual component's lengths and allocate enough memory to
          * hold combined path+query */
         size_t estimated_len = GRPC_SLICE_LENGTH(path_slice);
         estimated_len++; /* for the '?' */
         estimated_len += grpc_base64_estimate_encoded_size(
-            op->send_message->length, k_url_safe, k_multi_line);
+            op->payload->send_message.send_message->length, k_url_safe,
+            k_multi_line);
         estimated_len += 1; /* for the trailing 0 */
         grpc_slice path_with_query_slice = grpc_slice_malloc(estimated_len);
 
@@ -320,8 +325,8 @@ static grpc_error *hc_mutate_op(grpc_exec_ctx *exec_ctx,
         write_ptr++; /* for the '?' */
 
         grpc_base64_encode_core((char *)write_ptr, calld->payload_bytes,
-                                op->send_message->length, k_url_safe,
-                                k_multi_line);
+                                op->payload->send_message.send_message->length,
+                                k_url_safe, k_multi_line);
 
         /* remove trailing unused memory and add trailing 0 to terminate string
          */
@@ -335,14 +340,15 @@ static grpc_error *hc_mutate_op(grpc_exec_ctx *exec_ctx,
         /* substitute previous path with the new path+query */
         grpc_mdelem mdelem_path_and_query = grpc_mdelem_from_slices(
             exec_ctx, GRPC_MDSTR_PATH, path_with_query_slice);
-        grpc_metadata_batch *b = op->send_initial_metadata;
+        grpc_metadata_batch *b =
+            op->payload->send_initial_metadata.send_initial_metadata;
         error = grpc_metadata_batch_substitute(exec_ctx, b, b->idx.named.path,
                                                mdelem_path_and_query);
         if (error != GRPC_ERROR_NONE) return error;
 
         calld->on_complete = op->on_complete;
         op->on_complete = &calld->hc_on_complete;
-        op->send_message = NULL;
+        op->send_message = false;
         grpc_slice_unref_internal(exec_ctx, path_with_query_slice);
       } else {
         /* Not all data is available. Fall back to POST. */
@@ -353,47 +359,60 @@ static grpc_error *hc_mutate_op(grpc_exec_ctx *exec_ctx,
       }
     }
 
-    remove_if_present(exec_ctx, op->send_initial_metadata, GRPC_BATCH_METHOD);
-    remove_if_present(exec_ctx, op->send_initial_metadata, GRPC_BATCH_SCHEME);
-    remove_if_present(exec_ctx, op->send_initial_metadata, GRPC_BATCH_TE);
-    remove_if_present(exec_ctx, op->send_initial_metadata,
+    remove_if_present(exec_ctx,
+                      op->payload->send_initial_metadata.send_initial_metadata,
+                      GRPC_BATCH_METHOD);
+    remove_if_present(exec_ctx,
+                      op->payload->send_initial_metadata.send_initial_metadata,
+                      GRPC_BATCH_SCHEME);
+    remove_if_present(exec_ctx,
+                      op->payload->send_initial_metadata.send_initial_metadata,
+                      GRPC_BATCH_TE);
+    remove_if_present(exec_ctx,
+                      op->payload->send_initial_metadata.send_initial_metadata,
                       GRPC_BATCH_CONTENT_TYPE);
-    remove_if_present(exec_ctx, op->send_initial_metadata,
+    remove_if_present(exec_ctx,
+                      op->payload->send_initial_metadata.send_initial_metadata,
                       GRPC_BATCH_USER_AGENT);
 
     /* Send : prefixed headers, which have to be before any application
        layer headers. */
-    error = grpc_metadata_batch_add_head(exec_ctx, op->send_initial_metadata,
-                                         &calld->method, method);
+    error = grpc_metadata_batch_add_head(
+        exec_ctx, op->payload->send_initial_metadata.send_initial_metadata,
+        &calld->method, method);
     if (error != GRPC_ERROR_NONE) return error;
-    error =
-        grpc_metadata_batch_add_head(exec_ctx, op->send_initial_metadata,
-                                     &calld->scheme, channeld->static_scheme);
+    error = grpc_metadata_batch_add_head(
+        exec_ctx, op->payload->send_initial_metadata.send_initial_metadata,
+        &calld->scheme, channeld->static_scheme);
     if (error != GRPC_ERROR_NONE) return error;
-    error = grpc_metadata_batch_add_tail(exec_ctx, op->send_initial_metadata,
-                                         &calld->te_trailers,
-                                         GRPC_MDELEM_TE_TRAILERS);
+    error = grpc_metadata_batch_add_tail(
+        exec_ctx, op->payload->send_initial_metadata.send_initial_metadata,
+        &calld->te_trailers, GRPC_MDELEM_TE_TRAILERS);
     if (error != GRPC_ERROR_NONE) return error;
     error = grpc_metadata_batch_add_tail(
-        exec_ctx, op->send_initial_metadata, &calld->content_type,
-        GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC);
+        exec_ctx, op->payload->send_initial_metadata.send_initial_metadata,
+        &calld->content_type, GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC);
     if (error != GRPC_ERROR_NONE) return error;
-    error = grpc_metadata_batch_add_tail(exec_ctx, op->send_initial_metadata,
-                                         &calld->user_agent,
-                                         GRPC_MDELEM_REF(channeld->user_agent));
+    error = grpc_metadata_batch_add_tail(
+        exec_ctx, op->payload->send_initial_metadata.send_initial_metadata,
+        &calld->user_agent, GRPC_MDELEM_REF(channeld->user_agent));
     if (error != GRPC_ERROR_NONE) return error;
   }
 
-  if (op->recv_initial_metadata != NULL) {
+  if (op->recv_initial_metadata) {
     /* substitute our callback for the higher callback */
-    calld->recv_initial_metadata = op->recv_initial_metadata;
-    calld->on_done_recv_initial_metadata = op->recv_initial_metadata_ready;
-    op->recv_initial_metadata_ready = &calld->hc_on_recv_initial_metadata;
+    calld->recv_initial_metadata =
+        op->payload->recv_initial_metadata.recv_initial_metadata;
+    calld->on_done_recv_initial_metadata =
+        op->payload->recv_initial_metadata.recv_initial_metadata_ready;
+    op->payload->recv_initial_metadata.recv_initial_metadata_ready =
+        &calld->hc_on_recv_initial_metadata;
   }
 
-  if (op->recv_trailing_metadata != NULL) {
+  if (op->recv_trailing_metadata) {
     /* substitute our callback for the higher callback */
-    calld->recv_trailing_metadata = op->recv_trailing_metadata;
+    calld->recv_trailing_metadata =
+        op->payload->recv_trailing_metadata.recv_trailing_metadata;
     calld->on_done_recv_trailing_metadata = op->on_complete;
     op->on_complete = &calld->hc_on_recv_trailing_metadata;
   }
@@ -403,17 +422,17 @@ static grpc_error *hc_mutate_op(grpc_exec_ctx *exec_ctx,
 
 static void hc_start_transport_op(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_transport_stream_op *op) {
+                                  grpc_transport_stream_op_batch *op) {
   GPR_TIMER_BEGIN("hc_start_transport_op", 0);
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
   grpc_error *error = hc_mutate_op(exec_ctx, elem, op);
   if (error != GRPC_ERROR_NONE) {
-    grpc_transport_stream_op_finish_with_failure(exec_ctx, op, error);
+    grpc_transport_stream_op_batch_finish_with_failure(exec_ctx, op, error);
   } else {
     call_data *calld = elem->call_data;
-    if (op->send_message != NULL && calld->send_message_blocked) {
+    if (op->send_message && calld->send_message_blocked) {
       /* Don't forward the op. send_message contains slices that aren't ready
-      yet. The call will be forwarded by the op_complete of slice read call.
+         yet. The call will be forwarded by the op_complete of slice read call.
       */
     } else {
       grpc_call_next_op(exec_ctx, elem, op);
diff --git a/src/core/lib/channel/http_server_filter.c b/src/core/lib/channel/http_server_filter.c
index df0f95010b..c1e49ffacc 100644
--- a/src/core/lib/channel/http_server_filter.c
+++ b/src/core/lib/channel/http_server_filter.c
@@ -58,8 +58,7 @@ typedef struct call_data {
   bool payload_bin_delivered;
 
   grpc_metadata_batch *recv_initial_metadata;
-  bool *recv_idempotent_request;
-  bool *recv_cacheable_request;
+  uint32_t *recv_initial_metadata_flags;
   /** Closure to call when finished with the hs_on_recv hook */
   grpc_closure *on_done_recv;
   /** Closure to call when we retrieve read message from the path URI
@@ -116,14 +115,21 @@ static grpc_error *server_filter_incoming_metadata(grpc_exec_ctx *exec_ctx,
 
   if (b->idx.named.method != NULL) {
     if (grpc_mdelem_eq(b->idx.named.method->md, GRPC_MDELEM_METHOD_POST)) {
-      *calld->recv_idempotent_request = false;
-      *calld->recv_cacheable_request = false;
+      *calld->recv_initial_metadata_flags &=
+          ~(GRPC_INITIAL_METADATA_CACHEABLE_REQUEST |
+            GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST);
     } else if (grpc_mdelem_eq(b->idx.named.method->md,
                               GRPC_MDELEM_METHOD_PUT)) {
-      *calld->recv_idempotent_request = true;
+      *calld->recv_initial_metadata_flags &=
+          ~GRPC_INITIAL_METADATA_CACHEABLE_REQUEST;
+      *calld->recv_initial_metadata_flags |=
+          GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST;
     } else if (grpc_mdelem_eq(b->idx.named.method->md,
                               GRPC_MDELEM_METHOD_GET)) {
-      *calld->recv_cacheable_request = true;
+      *calld->recv_initial_metadata_flags |=
+          GRPC_INITIAL_METADATA_CACHEABLE_REQUEST;
+      *calld->recv_initial_metadata_flags &=
+          ~GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST;
     } else {
       add_error(error_name, &error,
                 grpc_attach_md_to_error(
@@ -206,7 +212,8 @@ static grpc_error *server_filter_incoming_metadata(grpc_exec_ctx *exec_ctx,
               grpc_error_set_str(
                   GRPC_ERROR_CREATE_FROM_STATIC_STRING("Missing header"),
                   GRPC_ERROR_STR_KEY, grpc_slice_from_static_string(":path")));
-  } else if (*calld->recv_cacheable_request == true) {
+  } else if (*calld->recv_initial_metadata_flags &
+             GRPC_INITIAL_METADATA_CACHEABLE_REQUEST) {
     /* We have a cacheable request made with GET verb. The path contains the
      * query parameter which is base64 encoded request payload. */
     const char k_query_separator = '?';
@@ -311,45 +318,53 @@ static void hs_recv_message_ready(grpc_exec_ctx *exec_ctx, void *user_data,
 }
 
 static void hs_mutate_op(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                         grpc_transport_stream_op *op) {
+                         grpc_transport_stream_op_batch *op) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
 
-  if (op->send_initial_metadata != NULL) {
+  if (op->send_initial_metadata) {
     grpc_error *error = GRPC_ERROR_NONE;
     static const char *error_name = "Failed sending initial metadata";
-    add_error(error_name, &error, grpc_metadata_batch_add_head(
-                                      exec_ctx, op->send_initial_metadata,
-                                      &calld->status, GRPC_MDELEM_STATUS_200));
-    add_error(error_name, &error,
-              grpc_metadata_batch_add_tail(
-                  exec_ctx, op->send_initial_metadata, &calld->content_type,
-                  GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC));
+    add_error(
+        error_name, &error,
+        grpc_metadata_batch_add_head(
+            exec_ctx, op->payload->send_initial_metadata.send_initial_metadata,
+            &calld->status, GRPC_MDELEM_STATUS_200));
+    add_error(
+        error_name, &error,
+        grpc_metadata_batch_add_tail(
+            exec_ctx, op->payload->send_initial_metadata.send_initial_metadata,
+            &calld->content_type,
+            GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC));
     add_error(error_name, &error,
-              server_filter_outgoing_metadata(exec_ctx, elem,
-                                              op->send_initial_metadata));
+              server_filter_outgoing_metadata(
+                  exec_ctx, elem,
+                  op->payload->send_initial_metadata.send_initial_metadata));
     if (error != GRPC_ERROR_NONE) {
-      grpc_transport_stream_op_finish_with_failure(exec_ctx, op, error);
+      grpc_transport_stream_op_batch_finish_with_failure(exec_ctx, op, error);
       return;
     }
   }
 
   if (op->recv_initial_metadata) {
     /* substitute our callback for the higher callback */
-    GPR_ASSERT(op->recv_idempotent_request != NULL);
-    GPR_ASSERT(op->recv_cacheable_request != NULL);
-    calld->recv_initial_metadata = op->recv_initial_metadata;
-    calld->recv_idempotent_request = op->recv_idempotent_request;
-    calld->recv_cacheable_request = op->recv_cacheable_request;
-    calld->on_done_recv = op->recv_initial_metadata_ready;
-    op->recv_initial_metadata_ready = &calld->hs_on_recv;
+    GPR_ASSERT(op->payload->recv_initial_metadata.recv_flags != NULL);
+    calld->recv_initial_metadata =
+        op->payload->recv_initial_metadata.recv_initial_metadata;
+    calld->recv_initial_metadata_flags =
+        op->payload->recv_initial_metadata.recv_flags;
+    calld->on_done_recv =
+        op->payload->recv_initial_metadata.recv_initial_metadata_ready;
+    op->payload->recv_initial_metadata.recv_initial_metadata_ready =
+        &calld->hs_on_recv;
   }
 
   if (op->recv_message) {
-    calld->recv_message_ready = op->recv_message_ready;
-    calld->pp_recv_message = op->recv_message;
-    if (op->recv_message_ready) {
-      op->recv_message_ready = &calld->hs_recv_message_ready;
+    calld->recv_message_ready = op->payload->recv_message.recv_message_ready;
+    calld->pp_recv_message = op->payload->recv_message.recv_message;
+    if (op->payload->recv_message.recv_message_ready) {
+      op->payload->recv_message.recv_message_ready =
+          &calld->hs_recv_message_ready;
     }
     if (op->on_complete) {
       calld->on_complete = op->on_complete;
@@ -359,9 +374,10 @@ static void hs_mutate_op(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 
   if (op->send_trailing_metadata) {
     grpc_error *error = server_filter_outgoing_metadata(
-        exec_ctx, elem, op->send_trailing_metadata);
+        exec_ctx, elem,
+        op->payload->send_trailing_metadata.send_trailing_metadata);
     if (error != GRPC_ERROR_NONE) {
-      grpc_transport_stream_op_finish_with_failure(exec_ctx, op, error);
+      grpc_transport_stream_op_batch_finish_with_failure(exec_ctx, op, error);
       return;
     }
   }
@@ -369,7 +385,7 @@ static void hs_mutate_op(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 
 static void hs_start_transport_op(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_transport_stream_op *op) {
+                                  grpc_transport_stream_op_batch *op) {
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
   GPR_TIMER_BEGIN("hs_start_transport_op", 0);
   hs_mutate_op(exec_ctx, elem, op);
diff --git a/src/core/lib/channel/message_size_filter.c b/src/core/lib/channel/message_size_filter.c
index 63136650a5..57726c8476 100644
--- a/src/core/lib/channel/message_size_filter.c
+++ b/src/core/lib/channel/message_size_filter.c
@@ -132,21 +132,23 @@ static void recv_message_ready(grpc_exec_ctx* exec_ctx, void* user_data,
     gpr_free(message_string);
   }
   // Invoke the next callback.
-  grpc_closure_sched(exec_ctx, calld->next_recv_message_ready, error);
+  grpc_closure_run(exec_ctx, calld->next_recv_message_ready, error);
 }
 
 // Start transport stream op.
-static void start_transport_stream_op(grpc_exec_ctx* exec_ctx,
-                                      grpc_call_element* elem,
-                                      grpc_transport_stream_op* op) {
+static void start_transport_stream_op_batch(
+    grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
+    grpc_transport_stream_op_batch* op) {
   call_data* calld = elem->call_data;
   // Check max send message size.
-  if (op->send_message != NULL && calld->max_send_size >= 0 &&
-      op->send_message->length > (size_t)calld->max_send_size) {
+  if (op->send_message && calld->max_send_size >= 0 &&
+      op->payload->send_message.send_message->length >
+          (size_t)calld->max_send_size) {
     char* message_string;
     gpr_asprintf(&message_string, "Sent message larger than max (%u vs. %d)",
-                 op->send_message->length, calld->max_send_size);
-    grpc_transport_stream_op_finish_with_failure(
+                 op->payload->send_message.send_message->length,
+                 calld->max_send_size);
+    grpc_transport_stream_op_batch_finish_with_failure(
         exec_ctx, op,
         grpc_error_set_int(GRPC_ERROR_CREATE_FROM_COPIED_STRING(message_string),
                            GRPC_ERROR_INT_GRPC_STATUS,
@@ -155,10 +157,11 @@ static void start_transport_stream_op(grpc_exec_ctx* exec_ctx,
     return;
   }
   // Inject callback for receiving a message.
-  if (op->recv_message_ready != NULL) {
-    calld->next_recv_message_ready = op->recv_message_ready;
-    calld->recv_message = op->recv_message;
-    op->recv_message_ready = &calld->recv_message_ready;
+  if (op->recv_message) {
+    calld->next_recv_message_ready =
+        op->payload->recv_message.recv_message_ready;
+    calld->recv_message = op->payload->recv_message.recv_message;
+    op->payload->recv_message.recv_message_ready = &calld->recv_message_ready;
   }
   // Chain to the next filter.
   grpc_call_next_op(exec_ctx, elem, op);
@@ -253,7 +256,7 @@ static void destroy_channel_elem(grpc_exec_ctx* exec_ctx,
 }
 
 const grpc_channel_filter grpc_message_size_filter = {
-    start_transport_stream_op,
+    start_transport_stream_op_batch,
     grpc_channel_next_op,
     sizeof(call_data),
     init_call_elem,
diff --git a/src/core/lib/iomgr/ev_epoll_linux.c b/src/core/lib/iomgr/ev_epoll_linux.c
index f6372c0f3f..7014b98349 100644
--- a/src/core/lib/iomgr/ev_epoll_linux.c
+++ b/src/core/lib/iomgr/ev_epoll_linux.c
@@ -56,6 +56,7 @@
 
 #include "src/core/lib/iomgr/ev_posix.h"
 #include "src/core/lib/iomgr/iomgr_internal.h"
+#include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/iomgr/wakeup_fd_posix.h"
 #include "src/core/lib/iomgr/workqueue.h"
 #include "src/core/lib/profiling/timers.h"
@@ -1467,8 +1468,9 @@ static int poll_deadline_to_millis_timeout(gpr_timespec deadline,
     return 0;
   }
   timeout = gpr_time_sub(deadline, now);
-  return gpr_time_to_millis(gpr_time_add(
+  int millis = gpr_time_to_millis(gpr_time_add(
       timeout, gpr_time_from_nanos(GPR_NS_PER_MS - 1, GPR_TIMESPAN)));
+  return millis >= 1 ? millis : 1;
 }
 
 static void fd_become_readable(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
@@ -1650,6 +1652,7 @@ static void pollset_work_and_unlock(grpc_exec_ctx *exec_ctx,
     for (int i = 0; i < ep_rv; ++i) {
       void *data_ptr = ep_ev[i].data.ptr;
       if (data_ptr == &global_wakeup_fd) {
+        grpc_timer_consume_kick();
         append_error(error, grpc_wakeup_fd_consume_wakeup(&global_wakeup_fd),
                      err_desc);
       } else if (data_ptr == &pi->workqueue_wakeup_fd) {
diff --git a/src/core/lib/iomgr/ev_poll_posix.c b/src/core/lib/iomgr/ev_poll_posix.c
index ca6e855611..d90f223362 100644
--- a/src/core/lib/iomgr/ev_poll_posix.c
+++ b/src/core/lib/iomgr/ev_poll_posix.c
@@ -52,6 +52,7 @@
 #include <grpc/support/useful.h>
 
 #include "src/core/lib/iomgr/iomgr_internal.h"
+#include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/iomgr/wakeup_fd_cv.h"
 #include "src/core/lib/iomgr/wakeup_fd_posix.h"
 #include "src/core/lib/profiling/timers.h"
@@ -1006,6 +1007,7 @@ static grpc_error *pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
         }
       } else {
         if (pfds[0].revents & POLLIN_CHECK) {
+          grpc_timer_consume_kick();
           work_combine_error(&error,
                              grpc_wakeup_fd_consume_wakeup(&global_wakeup_fd));
         }
diff --git a/src/core/lib/iomgr/timer.h b/src/core/lib/iomgr/timer.h
index d84a278b18..e0338f93c7 100644
--- a/src/core/lib/iomgr/timer.h
+++ b/src/core/lib/iomgr/timer.h
@@ -101,6 +101,9 @@ bool grpc_timer_check(grpc_exec_ctx *exec_ctx, gpr_timespec now,
 void grpc_timer_list_init(gpr_timespec now);
 void grpc_timer_list_shutdown(grpc_exec_ctx *exec_ctx);
 
+/* Consume a kick issued by grpc_kick_poller */
+void grpc_timer_consume_kick(void);
+
 /* the following must be implemented by each iomgr implementation */
 
 void grpc_kick_poller(void);
diff --git a/src/core/lib/iomgr/timer_generic.c b/src/core/lib/iomgr/timer_generic.c
index e53c801929..d8e6068431 100644
--- a/src/core/lib/iomgr/timer_generic.c
+++ b/src/core/lib/iomgr/timer_generic.c
@@ -37,9 +37,13 @@
 
 #include "src/core/lib/iomgr/timer.h"
 
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
+#include <grpc/support/tls.h>
 #include <grpc/support/useful.h>
+#include "src/core/lib/debug/trace.h"
 #include "src/core/lib/iomgr/time_averaged_stats.h"
 #include "src/core/lib/iomgr/timer_heap.h"
 #include "src/core/lib/support/spinlock.h"
@@ -52,12 +56,15 @@
 #define MIN_QUEUE_WINDOW_DURATION 0.01
 #define MAX_QUEUE_WINDOW_DURATION 1
 
+int grpc_timer_trace = 0;
+int grpc_timer_check_trace = 0;
+
 typedef struct {
   gpr_mu mu;
   grpc_time_averaged_stats stats;
   /* All and only timers with deadlines <= this will be in the heap. */
-  gpr_timespec queue_deadline_cap;
-  gpr_timespec min_deadline;
+  gpr_atm queue_deadline_cap;
+  gpr_atm min_deadline;
   /* Index in the g_shard_queue */
   uint32_t shard_queue_index;
   /* This holds all timers with deadlines < queue_deadline_cap. Timers in this
@@ -67,38 +74,92 @@ typedef struct {
   grpc_timer list;
 } shard_type;
 
-/* Protects g_shard_queue */
-static gpr_mu g_mu;
-/* Allow only one run_some_expired_timers at once */
-static gpr_spinlock g_checker_mu = GPR_SPINLOCK_STATIC_INITIALIZER;
+struct shared_mutables {
+  gpr_atm min_timer;
+  /* Allow only one run_some_expired_timers at once */
+  gpr_spinlock checker_mu;
+  bool initialized;
+  /* Protects g_shard_queue */
+  gpr_mu mu;
+} GPR_ALIGN_STRUCT(GPR_CACHELINE_SIZE);
+
+static struct shared_mutables g_shared_mutables = {
+    .checker_mu = GPR_SPINLOCK_STATIC_INITIALIZER, .initialized = false,
+};
 static gpr_clock_type g_clock_type;
 static shard_type g_shards[NUM_SHARDS];
-/* Protected by g_mu */
+/* Protected by g_shared_mutables.mu */
 static shard_type *g_shard_queue[NUM_SHARDS];
-static bool g_initialized = false;
+static gpr_timespec g_start_time;
+
+GPR_TLS_DECL(g_last_seen_min_timer);
+
+static gpr_atm saturating_add(gpr_atm a, gpr_atm b) {
+  if (a > GPR_ATM_MAX - b) {
+    return GPR_ATM_MAX;
+  }
+  return a + b;
+}
+
+static int run_some_expired_timers(grpc_exec_ctx *exec_ctx, gpr_atm now,
+                                   gpr_atm *next, grpc_error *error);
+
+static gpr_timespec dbl_to_ts(double d) {
+  gpr_timespec ts;
+  ts.tv_sec = (int64_t)d;
+  ts.tv_nsec = (int32_t)(1e9 * (d - (double)ts.tv_sec));
+  ts.clock_type = GPR_TIMESPAN;
+  return ts;
+}
+
+static gpr_atm timespec_to_atm_round_up(gpr_timespec ts) {
+  ts = gpr_time_sub(ts, g_start_time);
+  double x = GPR_MS_PER_SEC * (double)ts.tv_sec +
+             (double)ts.tv_nsec / GPR_NS_PER_MS +
+             (double)(GPR_NS_PER_SEC - 1) / (double)GPR_NS_PER_SEC;
+  if (x < 0) return 0;
+  if (x > GPR_ATM_MAX) return GPR_ATM_MAX;
+  return (gpr_atm)x;
+}
+
+static gpr_atm timespec_to_atm_round_down(gpr_timespec ts) {
+  ts = gpr_time_sub(ts, g_start_time);
+  double x =
+      GPR_MS_PER_SEC * (double)ts.tv_sec + (double)ts.tv_nsec / GPR_NS_PER_MS;
+  if (x < 0) return 0;
+  if (x > GPR_ATM_MAX) return GPR_ATM_MAX;
+  return (gpr_atm)x;
+}
 
-static int run_some_expired_timers(grpc_exec_ctx *exec_ctx, gpr_timespec now,
-                                   gpr_timespec *next, grpc_error *error);
+static gpr_timespec atm_to_timespec(gpr_atm x) {
+  return gpr_time_add(g_start_time, dbl_to_ts((double)x / 1000.0));
+}
 
-static gpr_timespec compute_min_deadline(shard_type *shard) {
+static gpr_atm compute_min_deadline(shard_type *shard) {
   return grpc_timer_heap_is_empty(&shard->heap)
-             ? shard->queue_deadline_cap
+             ? saturating_add(shard->queue_deadline_cap, 1)
              : grpc_timer_heap_top(&shard->heap)->deadline;
 }
 
 void grpc_timer_list_init(gpr_timespec now) {
   uint32_t i;
 
-  g_initialized = true;
-  gpr_mu_init(&g_mu);
+  g_shared_mutables.initialized = true;
+  gpr_mu_init(&g_shared_mutables.mu);
   g_clock_type = now.clock_type;
+  g_start_time = now;
+  g_shared_mutables.min_timer = timespec_to_atm_round_down(now);
+  gpr_tls_init(&g_last_seen_min_timer);
+  gpr_tls_set(&g_last_seen_min_timer, 0);
+  grpc_register_tracer("timer", &grpc_timer_trace);
+  grpc_register_tracer("timer_check", &grpc_timer_check_trace);
 
   for (i = 0; i < NUM_SHARDS; i++) {
     shard_type *shard = &g_shards[i];
     gpr_mu_init(&shard->mu);
     grpc_time_averaged_stats_init(&shard->stats, 1.0 / ADD_DEADLINE_SCALE, 0.1,
                                   0.5);
-    shard->queue_deadline_cap = now;
+    shard->queue_deadline_cap = g_shared_mutables.min_timer;
     shard->shard_queue_index = i;
     grpc_timer_heap_init(&shard->heap);
     shard->list.next = shard->list.prev = &shard->list;
@@ -110,29 +171,23 @@ void grpc_timer_list_init(gpr_timespec now) {
 void grpc_timer_list_shutdown(grpc_exec_ctx *exec_ctx) {
   int i;
   run_some_expired_timers(
-      exec_ctx, gpr_inf_future(g_clock_type), NULL,
+      exec_ctx, GPR_ATM_MAX, NULL,
       GRPC_ERROR_CREATE_FROM_STATIC_STRING("Timer list shutdown"));
   for (i = 0; i < NUM_SHARDS; i++) {
     shard_type *shard = &g_shards[i];
     gpr_mu_destroy(&shard->mu);
     grpc_timer_heap_destroy(&shard->heap);
   }
-  gpr_mu_destroy(&g_mu);
-  g_initialized = false;
+  gpr_mu_destroy(&g_shared_mutables.mu);
+  gpr_tls_destroy(&g_last_seen_min_timer);
+  g_shared_mutables.initialized = false;
 }
 
 static double ts_to_dbl(gpr_timespec ts) {
   return (double)ts.tv_sec + 1e-9 * ts.tv_nsec;
 }
 
-static gpr_timespec dbl_to_ts(double d) {
-  gpr_timespec ts;
-  ts.tv_sec = (int64_t)d;
-  ts.tv_nsec = (int32_t)(1e9 * (d - (double)ts.tv_sec));
-  ts.clock_type = GPR_TIMESPAN;
-  return ts;
-}
-
+/* returns true if the first element in the list */
 static void list_join(grpc_timer *head, grpc_timer *timer) {
   timer->next = head;
   timer->prev = head->prev;
@@ -158,15 +213,13 @@ static void swap_adjacent_shards_in_queue(uint32_t first_shard_queue_index) {
 
 static void note_deadline_change(shard_type *shard) {
   while (shard->shard_queue_index > 0 &&
-         gpr_time_cmp(
-             shard->min_deadline,
-             g_shard_queue[shard->shard_queue_index - 1]->min_deadline) < 0) {
+         shard->min_deadline <
+             g_shard_queue[shard->shard_queue_index - 1]->min_deadline) {
     swap_adjacent_shards_in_queue(shard->shard_queue_index - 1);
   }
   while (shard->shard_queue_index < NUM_SHARDS - 1 &&
-         gpr_time_cmp(
-             shard->min_deadline,
-             g_shard_queue[shard->shard_queue_index + 1]->min_deadline) > 0) {
+         shard->min_deadline >
+             g_shard_queue[shard->shard_queue_index + 1]->min_deadline) {
     swap_adjacent_shards_in_queue(shard->shard_queue_index);
   }
 }
@@ -179,9 +232,17 @@ void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
   GPR_ASSERT(deadline.clock_type == g_clock_type);
   GPR_ASSERT(now.clock_type == g_clock_type);
   timer->closure = closure;
-  timer->deadline = deadline;
+  timer->deadline = timespec_to_atm_round_up(deadline);
+
+  if (grpc_timer_trace) {
+    gpr_log(GPR_DEBUG, "TIMER %p: SET %" PRId64 ".%09d [%" PRIdPTR
+                       "] now %" PRId64 ".%09d [%" PRIdPTR "] call %p[%p]",
+            timer, deadline.tv_sec, deadline.tv_nsec, timer->deadline,
+            now.tv_sec, now.tv_nsec, timespec_to_atm_round_down(now), closure,
+            closure->cb);
+  }
 
-  if (!g_initialized) {
+  if (!g_shared_mutables.initialized) {
     timer->pending = false;
     grpc_closure_sched(exec_ctx, timer->closure,
                        GRPC_ERROR_CREATE_FROM_STATIC_STRING(
@@ -201,12 +262,18 @@ void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
 
   grpc_time_averaged_stats_add_sample(&shard->stats,
                                       ts_to_dbl(gpr_time_sub(deadline, now)));
-  if (gpr_time_cmp(deadline, shard->queue_deadline_cap) < 0) {
+  if (timer->deadline < shard->queue_deadline_cap) {
     is_first_timer = grpc_timer_heap_add(&shard->heap, timer);
   } else {
     timer->heap_index = INVALID_HEAP_INDEX;
     list_join(&shard->list, timer);
   }
+  if (grpc_timer_trace) {
+    gpr_log(GPR_DEBUG, "  .. add to shard %d with queue_deadline_cap=%" PRIdPTR
+                       " => is_first_timer=%s",
+            (int)(shard - g_shards), shard->queue_deadline_cap,
+            is_first_timer ? "true" : "false");
+  }
   gpr_mu_unlock(&shard->mu);
 
   /* Deadline may have decreased, we need to adjust the master queue.  Note
@@ -221,28 +288,41 @@ void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
      In that case, the timer will simply have to wait for the next
      grpc_timer_check. */
   if (is_first_timer) {
-    gpr_mu_lock(&g_mu);
-    if (gpr_time_cmp(deadline, shard->min_deadline) < 0) {
-      gpr_timespec old_min_deadline = g_shard_queue[0]->min_deadline;
-      shard->min_deadline = deadline;
+    gpr_mu_lock(&g_shared_mutables.mu);
+    if (grpc_timer_trace) {
+      gpr_log(GPR_DEBUG, "  .. old shard min_deadline=%" PRIdPTR,
+              shard->min_deadline);
+    }
+    if (timer->deadline < shard->min_deadline) {
+      gpr_atm old_min_deadline = g_shard_queue[0]->min_deadline;
+      shard->min_deadline = timer->deadline;
       note_deadline_change(shard);
-      if (shard->shard_queue_index == 0 &&
-          gpr_time_cmp(deadline, old_min_deadline) < 0) {
+      if (shard->shard_queue_index == 0 && timer->deadline < old_min_deadline) {
+        gpr_atm_no_barrier_store(&g_shared_mutables.min_timer, timer->deadline);
         grpc_kick_poller();
       }
     }
-    gpr_mu_unlock(&g_mu);
+    gpr_mu_unlock(&g_shared_mutables.mu);
   }
 }
 
+void grpc_timer_consume_kick(void) {
+  /* force re-evaluation of last seeen min */
+  gpr_tls_set(&g_last_seen_min_timer, 0);
+}
+
 void grpc_timer_cancel(grpc_exec_ctx *exec_ctx, grpc_timer *timer) {
-  if (!g_initialized) {
+  if (!g_shared_mutables.initialized) {
     /* must have already been cancelled, also the shard mutex is invalid */
     return;
   }
 
   shard_type *shard = &g_shards[GPR_HASH_POINTER(timer, NUM_SHARDS)];
   gpr_mu_lock(&shard->mu);
+  if (grpc_timer_trace) {
+    gpr_log(GPR_DEBUG, "TIMER %p: CANCEL pending=%s", timer,
+            timer->pending ? "true" : "false");
+  }
   if (timer->pending) {
     grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_CANCELLED);
     timer->pending = false;
@@ -260,7 +340,7 @@ void grpc_timer_cancel(grpc_exec_ctx *exec_ctx, grpc_timer *timer) {
    for timers that fall at or under it.  Returns true if the queue is no
    longer empty.
    REQUIRES: shard->mu locked */
-static int refill_queue(shard_type *shard, gpr_timespec now) {
+static int refill_queue(shard_type *shard, gpr_atm now) {
   /* Compute the new queue window width and bound by the limits: */
   double computed_deadline_delta =
       grpc_time_averaged_stats_update_average(&shard->stats) *
@@ -271,12 +351,22 @@ static int refill_queue(shard_type *shard, gpr_timespec now) {
   grpc_timer *timer, *next;
 
   /* Compute the new cap and put all timers under it into the queue: */
-  shard->queue_deadline_cap = gpr_time_add(
-      gpr_time_max(now, shard->queue_deadline_cap), dbl_to_ts(deadline_delta));
+  shard->queue_deadline_cap =
+      saturating_add(GPR_MAX(now, shard->queue_deadline_cap),
+                     (gpr_atm)(deadline_delta * 1000.0));
+
+  if (grpc_timer_check_trace) {
+    gpr_log(GPR_DEBUG, "  .. shard[%d]->queue_deadline_cap --> %" PRIdPTR,
+            (int)(shard - g_shards), shard->queue_deadline_cap);
+  }
   for (timer = shard->list.next; timer != &shard->list; timer = next) {
     next = timer->next;
 
-    if (gpr_time_cmp(timer->deadline, shard->queue_deadline_cap) < 0) {
+    if (timer->deadline < shard->queue_deadline_cap) {
+      if (grpc_timer_check_trace) {
+        gpr_log(GPR_DEBUG, "  .. add timer with deadline %" PRIdPTR " to heap",
+                timer->deadline);
+      }
       list_remove(timer);
       grpc_timer_heap_add(&shard->heap, timer);
     }
@@ -287,15 +377,29 @@ static int refill_queue(shard_type *shard, gpr_timespec now) {
 /* This pops the next non-cancelled timer with deadline <= now from the
    queue, or returns NULL if there isn't one.
    REQUIRES: shard->mu locked */
-static grpc_timer *pop_one(shard_type *shard, gpr_timespec now) {
+static grpc_timer *pop_one(shard_type *shard, gpr_atm now) {
   grpc_timer *timer;
   for (;;) {
+    if (grpc_timer_check_trace) {
+      gpr_log(GPR_DEBUG, "  .. shard[%d]: heap_empty=%s",
+              (int)(shard - g_shards),
+              grpc_timer_heap_is_empty(&shard->heap) ? "true" : "false");
+    }
     if (grpc_timer_heap_is_empty(&shard->heap)) {
-      if (gpr_time_cmp(now, shard->queue_deadline_cap) < 0) return NULL;
+      if (now < shard->queue_deadline_cap) return NULL;
       if (!refill_queue(shard, now)) return NULL;
     }
     timer = grpc_timer_heap_top(&shard->heap);
-    if (gpr_time_cmp(timer->deadline, now) > 0) return NULL;
+    if (grpc_timer_check_trace) {
+      gpr_log(GPR_DEBUG,
+              "  .. check top timer deadline=%" PRIdPTR " now=%" PRIdPTR,
+              timer->deadline, now);
+    }
+    if (timer->deadline > now) return NULL;
+    if (grpc_timer_trace) {
+      gpr_log(GPR_DEBUG, "TIMER %p: FIRE %" PRIdPTR "ms late", timer,
+              now - timer->deadline);
+    }
     timer->pending = false;
     grpc_timer_heap_pop(&shard->heap);
     return timer;
@@ -304,7 +408,7 @@ static grpc_timer *pop_one(shard_type *shard, gpr_timespec now) {
 
 /* REQUIRES: shard->mu unlocked */
 static size_t pop_timers(grpc_exec_ctx *exec_ctx, shard_type *shard,
-                         gpr_timespec now, gpr_timespec *new_min_deadline,
+                         gpr_atm now, gpr_atm *new_min_deadline,
                          grpc_error *error) {
   size_t n = 0;
   grpc_timer *timer;
@@ -318,17 +422,29 @@ static size_t pop_timers(grpc_exec_ctx *exec_ctx, shard_type *shard,
   return n;
 }
 
-static int run_some_expired_timers(grpc_exec_ctx *exec_ctx, gpr_timespec now,
-                                   gpr_timespec *next, grpc_error *error) {
+static int run_some_expired_timers(grpc_exec_ctx *exec_ctx, gpr_atm now,
+                                   gpr_atm *next, grpc_error *error) {
   size_t n = 0;
 
-  /* TODO(ctiller): verify that there are any timers (atomically) here */
+  gpr_atm min_timer = gpr_atm_no_barrier_load(&g_shared_mutables.min_timer);
+  gpr_tls_set(&g_last_seen_min_timer, min_timer);
+  if (now < min_timer) {
+    if (next != NULL) *next = GPR_MIN(*next, min_timer);
+    return 0;
+  }
 
-  if (gpr_spinlock_trylock(&g_checker_mu)) {
-    gpr_mu_lock(&g_mu);
+  if (gpr_spinlock_trylock(&g_shared_mutables.checker_mu)) {
+    gpr_mu_lock(&g_shared_mutables.mu);
 
-    while (gpr_time_cmp(g_shard_queue[0]->min_deadline, now) < 0) {
-      gpr_timespec new_min_deadline;
+    if (grpc_timer_check_trace) {
+      gpr_log(GPR_DEBUG, "  .. shard[%d]->min_deadline = %" PRIdPTR,
+              (int)(g_shard_queue[0] - g_shards),
+              g_shard_queue[0]->min_deadline);
+    }
+
+    while (g_shard_queue[0]->min_deadline < now ||
+           (now != GPR_ATM_MAX && g_shard_queue[0]->min_deadline == now)) {
+      gpr_atm new_min_deadline;
 
       /* For efficiency, we pop as many available timers as we can from the
          shard.  This may violate perfect timer deadline ordering, but that
@@ -336,6 +452,14 @@ static int run_some_expired_timers(grpc_exec_ctx *exec_ctx, gpr_timespec now,
       n +=
           pop_timers(exec_ctx, g_shard_queue[0], now, &new_min_deadline, error);
 
+      if (grpc_timer_check_trace) {
+        gpr_log(GPR_DEBUG, "  .. popped --> %" PRIdPTR
+                           ", shard[%d]->min_deadline %" PRIdPTR
+                           " --> %" PRIdPTR ", now=%" PRIdPTR,
+                n, (int)(g_shard_queue[0] - g_shards),
+                g_shard_queue[0]->min_deadline, new_min_deadline, now);
+      }
+
       /* An grpc_timer_init() on the shard could intervene here, adding a new
          timer that is earlier than new_min_deadline.  However,
          grpc_timer_init() will block on the master_lock before it can call
@@ -346,23 +470,24 @@ static int run_some_expired_timers(grpc_exec_ctx *exec_ctx, gpr_timespec now,
     }
 
     if (next) {
-      *next = gpr_time_min(*next, g_shard_queue[0]->min_deadline);
+      *next = GPR_MIN(*next, g_shard_queue[0]->min_deadline);
     }
 
-    gpr_mu_unlock(&g_mu);
-    gpr_spinlock_unlock(&g_checker_mu);
+    gpr_atm_no_barrier_store(&g_shared_mutables.min_timer,
+                             g_shard_queue[0]->min_deadline);
+    gpr_mu_unlock(&g_shared_mutables.mu);
+    gpr_spinlock_unlock(&g_shared_mutables.checker_mu);
   } else if (next != NULL) {
     /* TODO(ctiller): this forces calling code to do an short poll, and
        then retry the timer check (because this time through the timer list was
        contended).
 
-       We could reduce the cost here dramatically by keeping a count of how many
-       currently active pollers got through the uncontended case above
+       We could reduce the cost here dramatically by keeping a count of how
+       many currently active pollers got through the uncontended case above
        successfully, and waking up other pollers IFF that count drops to zero.
 
        Once that count is in place, this entire else branch could disappear. */
-    *next = gpr_time_min(
-        *next, gpr_time_add(now, gpr_time_from_millis(1, GPR_TIMESPAN)));
+    *next = GPR_MIN(*next, now + 1);
   }
 
   GRPC_ERROR_UNREF(error);
@@ -372,12 +497,71 @@ static int run_some_expired_timers(grpc_exec_ctx *exec_ctx, gpr_timespec now,
 
 bool grpc_timer_check(grpc_exec_ctx *exec_ctx, gpr_timespec now,
                       gpr_timespec *next) {
+  // prelude
   GPR_ASSERT(now.clock_type == g_clock_type);
-  return run_some_expired_timers(
-      exec_ctx, now, next,
+  gpr_atm now_atm = timespec_to_atm_round_down(now);
+
+  /* fetch from a thread-local first: this avoids contention on a globally
+     mutable cacheline in the common case */
+  gpr_atm min_timer = gpr_tls_get(&g_last_seen_min_timer);
+  if (now_atm < min_timer) {
+    if (next != NULL) {
+      *next =
+          atm_to_timespec(GPR_MIN(timespec_to_atm_round_up(*next), min_timer));
+    }
+    if (grpc_timer_check_trace) {
+      gpr_log(GPR_DEBUG,
+              "TIMER CHECK SKIP: now_atm=%" PRIdPTR " min_timer=%" PRIdPTR,
+              now_atm, min_timer);
+    }
+    return 0;
+  }
+
+  grpc_error *shutdown_error =
       gpr_time_cmp(now, gpr_inf_future(now.clock_type)) != 0
           ? GRPC_ERROR_NONE
-          : GRPC_ERROR_CREATE_FROM_STATIC_STRING("Shutting down timer system"));
+          : GRPC_ERROR_CREATE_FROM_STATIC_STRING("Shutting down timer system");
+
+  // tracing
+  if (grpc_timer_check_trace) {
+    char *next_str;
+    if (next == NULL) {
+      next_str = gpr_strdup("NULL");
+    } else {
+      gpr_asprintf(&next_str, "%" PRId64 ".%09d [%" PRIdPTR "]", next->tv_sec,
+                   next->tv_nsec, timespec_to_atm_round_down(*next));
+    }
+    gpr_log(GPR_DEBUG, "TIMER CHECK BEGIN: now=%" PRId64 ".%09d [%" PRIdPTR
+                       "] next=%s tls_min=%" PRIdPTR " glob_min=%" PRIdPTR,
+            now.tv_sec, now.tv_nsec, now_atm, next_str,
+            gpr_tls_get(&g_last_seen_min_timer),
+            gpr_atm_no_barrier_load(&g_shared_mutables.min_timer));
+    gpr_free(next_str);
+  }
+  // actual code
+  bool r;
+  gpr_atm next_atm;
+  if (next == NULL) {
+    r = run_some_expired_timers(exec_ctx, now_atm, NULL, shutdown_error);
+  } else {
+    next_atm = timespec_to_atm_round_down(*next);
+    r = run_some_expired_timers(exec_ctx, now_atm, &next_atm, shutdown_error);
+    *next = atm_to_timespec(next_atm);
+  }
+  // tracing
+  if (grpc_timer_check_trace) {
+    char *next_str;
+    if (next == NULL) {
+      next_str = gpr_strdup("NULL");
+    } else {
+      gpr_asprintf(&next_str, "%" PRId64 ".%09d [%" PRIdPTR "]", next->tv_sec,
+                   next->tv_nsec, next_atm);
+    }
+    gpr_log(GPR_DEBUG, "TIMER CHECK END: %d timers triggered; next=%s", r,
+            next_str);
+    gpr_free(next_str);
+  }
+  return r > 0;
 }
 
 #endif /* GRPC_TIMER_USE_GENERIC */
diff --git a/src/core/lib/iomgr/timer_generic.h b/src/core/lib/iomgr/timer_generic.h
index 1608dce9fb..c79a431aa0 100644
--- a/src/core/lib/iomgr/timer_generic.h
+++ b/src/core/lib/iomgr/timer_generic.h
@@ -38,7 +38,7 @@
 #include "src/core/lib/iomgr/exec_ctx.h"
 
 struct grpc_timer {
-  gpr_timespec deadline;
+  gpr_atm deadline;
   uint32_t heap_index; /* INVALID_HEAP_INDEX if not in heap */
   bool pending;
   struct grpc_timer *next;
diff --git a/src/core/lib/iomgr/timer_heap.c b/src/core/lib/iomgr/timer_heap.c
index f736d335e6..03ccfe023a 100644
--- a/src/core/lib/iomgr/timer_heap.c
+++ b/src/core/lib/iomgr/timer_heap.c
@@ -50,7 +50,7 @@
 static void adjust_upwards(grpc_timer **first, uint32_t i, grpc_timer *t) {
   while (i > 0) {
     uint32_t parent = (uint32_t)(((int)i - 1) / 2);
-    if (gpr_time_cmp(first[parent]->deadline, t->deadline) <= 0) break;
+    if (first[parent]->deadline <= t->deadline) break;
     first[i] = first[parent];
     first[i]->heap_index = i;
     i = parent;
@@ -68,12 +68,12 @@ static void adjust_downwards(grpc_timer **first, uint32_t i, uint32_t length,
     uint32_t left_child = 1u + 2u * i;
     if (left_child >= length) break;
     uint32_t right_child = left_child + 1;
-    uint32_t next_i = right_child < length &&
-                              gpr_time_cmp(first[left_child]->deadline,
-                                           first[right_child]->deadline) > 0
-                          ? right_child
-                          : left_child;
-    if (gpr_time_cmp(t->deadline, first[next_i]->deadline) <= 0) break;
+    uint32_t next_i =
+        right_child < length &&
+                first[left_child]->deadline > first[right_child]->deadline
+            ? right_child
+            : left_child;
+    if (t->deadline <= first[next_i]->deadline) break;
     first[i] = first[next_i];
     first[i]->heap_index = i;
     i = next_i;
@@ -97,7 +97,7 @@ static void maybe_shrink(grpc_timer_heap *heap) {
 static void note_changed_priority(grpc_timer_heap *heap, grpc_timer *timer) {
   uint32_t i = timer->heap_index;
   uint32_t parent = (uint32_t)(((int)i - 1) / 2);
-  if (gpr_time_cmp(heap->timers[parent]->deadline, timer->deadline) > 0) {
+  if (heap->timers[parent]->deadline > timer->deadline) {
     adjust_upwards(heap->timers, i, timer);
   } else {
     adjust_downwards(heap->timers, i, heap->timer_count, timer);
diff --git a/src/core/lib/security/transport/client_auth_filter.c b/src/core/lib/security/transport/client_auth_filter.c
index 8f321b9911..f526653ffa 100644
--- a/src/core/lib/security/transport/client_auth_filter.c
+++ b/src/core/lib/security/transport/client_auth_filter.c
@@ -64,7 +64,7 @@ typedef struct {
      pollset_set so that work can progress when this call wants work to progress
   */
   grpc_polling_entity *pollent;
-  grpc_transport_stream_op op;
+  grpc_transport_stream_op_batch op;
   uint8_t security_context_set;
   grpc_linked_mdelem md_links[MAX_CREDENTIALS_METADATA_COUNT];
   grpc_auth_metadata_context auth_md_context;
@@ -108,7 +108,7 @@ static void on_credentials_metadata(grpc_exec_ctx *exec_ctx, void *user_data,
                                     const char *error_details) {
   grpc_call_element *elem = (grpc_call_element *)user_data;
   call_data *calld = elem->call_data;
-  grpc_transport_stream_op *op = &calld->op;
+  grpc_transport_stream_op_batch *op = &calld->op;
   grpc_metadata_batch *mdb;
   size_t i;
   reset_auth_metadata_context(&calld->auth_md_context);
@@ -122,8 +122,8 @@ static void on_credentials_metadata(grpc_exec_ctx *exec_ctx, void *user_data,
         GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAUTHENTICATED);
   } else {
     GPR_ASSERT(num_md <= MAX_CREDENTIALS_METADATA_COUNT);
-    GPR_ASSERT(op->send_initial_metadata != NULL);
-    mdb = op->send_initial_metadata;
+    GPR_ASSERT(op->send_initial_metadata);
+    mdb = op->payload->send_initial_metadata.send_initial_metadata;
     for (i = 0; i < num_md; i++) {
       add_error(&error,
                 grpc_metadata_batch_add_tail(
@@ -136,7 +136,7 @@ static void on_credentials_metadata(grpc_exec_ctx *exec_ctx, void *user_data,
   if (error == GRPC_ERROR_NONE) {
     grpc_call_next_op(exec_ctx, elem, op);
   } else {
-    grpc_transport_stream_op_finish_with_failure(exec_ctx, op, error);
+    grpc_transport_stream_op_batch_finish_with_failure(exec_ctx, op, error);
   }
 }
 
@@ -172,11 +172,13 @@ void build_auth_metadata_context(grpc_security_connector *sc,
 
 static void send_security_metadata(grpc_exec_ctx *exec_ctx,
                                    grpc_call_element *elem,
-                                   grpc_transport_stream_op *op) {
+                                   grpc_transport_stream_op_batch *op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   grpc_client_security_context *ctx =
-      (grpc_client_security_context *)op->context[GRPC_CONTEXT_SECURITY].value;
+      (grpc_client_security_context *)op->payload
+          ->context[GRPC_CONTEXT_SECURITY]
+          .value;
   grpc_call_credentials *channel_call_creds =
       chand->security_connector->request_metadata_creds;
   int call_creds_has_md = (ctx != NULL) && (ctx->creds != NULL);
@@ -191,7 +193,7 @@ static void send_security_metadata(grpc_exec_ctx *exec_ctx,
     calld->creds = grpc_composite_call_credentials_create(channel_call_creds,
                                                           ctx->creds, NULL);
     if (calld->creds == NULL) {
-      grpc_transport_stream_op_finish_with_failure(
+      grpc_transport_stream_op_batch_finish_with_failure(
           exec_ctx, op,
           grpc_error_set_int(
               GRPC_ERROR_CREATE_FROM_STATIC_STRING(
@@ -242,7 +244,7 @@ static void on_host_checked(grpc_exec_ctx *exec_ctx, void *user_data,
    that is being sent or received. */
 static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
                                     grpc_call_element *elem,
-                                    grpc_transport_stream_op *op) {
+                                    grpc_transport_stream_op_batch *op) {
   GPR_TIMER_BEGIN("auth_start_transport_op", 0);
 
   /* grab pointers to our data from the call element */
@@ -251,23 +253,25 @@ static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
   grpc_linked_mdelem *l;
   grpc_client_security_context *sec_ctx = NULL;
 
-  if (calld->security_context_set == 0 && op->cancel_error == GRPC_ERROR_NONE) {
+  if (calld->security_context_set == 0 && !op->cancel_stream) {
     calld->security_context_set = 1;
-    GPR_ASSERT(op->context);
-    if (op->context[GRPC_CONTEXT_SECURITY].value == NULL) {
-      op->context[GRPC_CONTEXT_SECURITY].value =
+    GPR_ASSERT(op->payload->context != NULL);
+    if (op->payload->context[GRPC_CONTEXT_SECURITY].value == NULL) {
+      op->payload->context[GRPC_CONTEXT_SECURITY].value =
           grpc_client_security_context_create();
-      op->context[GRPC_CONTEXT_SECURITY].destroy =
+      op->payload->context[GRPC_CONTEXT_SECURITY].destroy =
           grpc_client_security_context_destroy;
     }
-    sec_ctx = op->context[GRPC_CONTEXT_SECURITY].value;
+    sec_ctx = op->payload->context[GRPC_CONTEXT_SECURITY].value;
     GRPC_AUTH_CONTEXT_UNREF(sec_ctx->auth_context, "client auth filter");
     sec_ctx->auth_context =
         GRPC_AUTH_CONTEXT_REF(chand->auth_context, "client_auth_filter");
   }
 
-  if (op->send_initial_metadata != NULL) {
-    for (l = op->send_initial_metadata->list.head; l != NULL; l = l->next) {
+  if (op->send_initial_metadata) {
+    for (l = op->payload->send_initial_metadata.send_initial_metadata->list
+                 .head;
+         l != NULL; l = l->next) {
       grpc_mdelem md = l->md;
       /* Pointer comparison is OK for md_elems created from the same context.
        */
diff --git a/src/core/lib/security/transport/server_auth_filter.c b/src/core/lib/security/transport/server_auth_filter.c
index 3cf0632220..1aca76f9e8 100644
--- a/src/core/lib/security/transport/server_auth_filter.c
+++ b/src/core/lib/security/transport/server_auth_filter.c
@@ -49,7 +49,7 @@ typedef struct call_data {
      up-call on transport_op, and remember to call our on_done_recv member after
      handling it. */
   grpc_closure auth_on_recv;
-  grpc_transport_stream_op *transport_op;
+  grpc_transport_stream_op_batch *transport_op;
   grpc_metadata_array md;
   const grpc_metadata *consumed_md;
   size_t num_consumed_md;
@@ -138,12 +138,11 @@ static void on_md_processing_done(
     error_details = error_details != NULL
                         ? error_details
                         : "Authentication metadata processing failed.";
-    calld->transport_op->send_initial_metadata = NULL;
-    if (calld->transport_op->send_message != NULL) {
-      grpc_byte_stream_destroy(&exec_ctx, calld->transport_op->send_message);
-      calld->transport_op->send_message = NULL;
+    if (calld->transport_op->send_message) {
+      grpc_byte_stream_destroy(
+          &exec_ctx, calld->transport_op->payload->send_message.send_message);
+      calld->transport_op->payload->send_message.send_message = NULL;
     }
-    calld->transport_op->send_trailing_metadata = NULL;
     grpc_closure_sched(
         &exec_ctx, calld->on_done_recv,
         grpc_error_set_int(GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_details),
@@ -171,14 +170,17 @@ static void auth_on_recv(grpc_exec_ctx *exec_ctx, void *user_data,
 }
 
 static void set_recv_ops_md_callbacks(grpc_call_element *elem,
-                                      grpc_transport_stream_op *op) {
+                                      grpc_transport_stream_op_batch *op) {
   call_data *calld = elem->call_data;
 
-  if (op->recv_initial_metadata != NULL) {
+  if (op->recv_initial_metadata) {
     /* substitute our callback for the higher callback */
-    calld->recv_initial_metadata = op->recv_initial_metadata;
-    calld->on_done_recv = op->recv_initial_metadata_ready;
-    op->recv_initial_metadata_ready = &calld->auth_on_recv;
+    calld->recv_initial_metadata =
+        op->payload->recv_initial_metadata.recv_initial_metadata;
+    calld->on_done_recv =
+        op->payload->recv_initial_metadata.recv_initial_metadata_ready;
+    op->payload->recv_initial_metadata.recv_initial_metadata_ready =
+        &calld->auth_on_recv;
     calld->transport_op = op;
   }
 }
@@ -190,7 +192,7 @@ static void set_recv_ops_md_callbacks(grpc_call_element *elem,
    that is being sent or received. */
 static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
                                     grpc_call_element *elem,
-                                    grpc_transport_stream_op *op) {
+                                    grpc_transport_stream_op_batch *op) {
   set_recv_ops_md_callbacks(elem, op);
   grpc_call_next_op(exec_ctx, elem, op);
 }
diff --git a/src/core/lib/surface/call.c b/src/core/lib/surface/call.c
index a9317a4694..87787b3eea 100644
--- a/src/core/lib/surface/call.c
+++ b/src/core/lib/surface/call.c
@@ -117,25 +117,32 @@ static received_status unpack_received_status(gpr_atm atm) {
 
 typedef struct batch_control {
   grpc_call *call;
-  grpc_cq_completion cq_completion;
+  /* Share memory for cq_completion and notify_tag as they are never needed
+     simultaneously. Each byte used in this data structure count as six bytes
+     per call, so any savings we can make are worthwhile,
+
+     We use notify_tag to determine whether or not to send notification to the
+     completion queue. Once we've made that determination, we can reuse the
+     memory for cq_completion. */
+  union {
+    grpc_cq_completion cq_completion;
+    struct {
+      /* Any given op indicates completion by either (a) calling a closure or
+         (b) sending a notification on the call's completion queue.  If
+         \a is_closure is true, \a tag indicates a closure to be invoked;
+         otherwise, \a tag indicates the tag to be used in the notification to
+         be sent to the completion queue. */
+      void *tag;
+      bool is_closure;
+    } notify_tag;
+  } completion_data;
   grpc_closure finish_batch;
-  void *notify_tag;
   gpr_refcount steps_to_complete;
 
   grpc_error *errors[MAX_ERRORS_PER_BATCH];
   gpr_atm num_errors;
 
-  uint8_t send_initial_metadata;
-  uint8_t send_message;
-  uint8_t send_final_op;
-  uint8_t recv_initial_metadata;
-  uint8_t recv_message;
-  uint8_t recv_final_op;
-  uint8_t is_notify_tag_closure;
-
-  /* TODO(ctiller): now that this is inlined, figure out how much of the above
-                    state can be eliminated */
-  grpc_transport_stream_op op;
+  grpc_transport_stream_op_batch op;
 } batch_control;
 
 struct grpc_call {
@@ -169,6 +176,7 @@ struct grpc_call {
   bool has_initial_md_been_received;
 
   batch_control active_batches[MAX_CONCURRENT_BATCHES];
+  grpc_transport_stream_op_batch_payload stream_op_payload;
 
   /* first idx: is_receiving, second idx: is_trailing */
   grpc_metadata_batch metadata_batch[2][2];
@@ -239,7 +247,7 @@ int grpc_call_error_trace = 0;
   CALL_FROM_CALL_STACK(grpc_call_stack_from_top_element(top_elem))
 
 static void execute_op(grpc_exec_ctx *exec_ctx, grpc_call *call,
-                       grpc_transport_stream_op *op);
+                       grpc_transport_stream_op_batch *op);
 static void cancel_with_status(grpc_exec_ctx *exec_ctx, grpc_call *c,
                                status_source source, grpc_status_code status,
                                const char *description);
@@ -291,6 +299,7 @@ grpc_error *grpc_call_create(grpc_exec_ctx *exec_ctx,
   /* Always support no compression */
   GPR_BITSET(&call->encodings_accepted_by_peer, GRPC_COMPRESS_NONE);
   call->is_client = args->server_transport_data == NULL;
+  call->stream_op_payload.context = call->context;
   grpc_slice path = grpc_empty_slice();
   if (call->is_client) {
     GPR_ASSERT(args->add_initial_metadata_count <
@@ -535,13 +544,12 @@ grpc_call_error grpc_call_cancel(grpc_call *call, void *reserved) {
 }
 
 static void execute_op(grpc_exec_ctx *exec_ctx, grpc_call *call,
-                       grpc_transport_stream_op *op) {
+                       grpc_transport_stream_op_batch *op) {
   grpc_call_element *elem;
 
   GPR_TIMER_BEGIN("execute_op", 0);
   elem = CALL_ELEM_FROM_CALL(call, 0);
-  op->context = call->context;
-  elem->filter->start_transport_stream_op(exec_ctx, elem, op);
+  elem->filter->start_transport_stream_op_batch(exec_ctx, elem, op);
   GPR_TIMER_END("execute_op", 0);
 }
 
@@ -594,9 +602,10 @@ static void cancel_with_error(grpc_exec_ctx *exec_ctx, grpc_call *c,
                               status_source source, grpc_error *error) {
   GRPC_CALL_INTERNAL_REF(c, "termination");
   set_status_from_error(exec_ctx, c, source, GRPC_ERROR_REF(error));
-  grpc_transport_stream_op *op = grpc_make_transport_stream_op(
+  grpc_transport_stream_op_batch *op = grpc_make_transport_stream_op(
       grpc_closure_create(done_termination, c, grpc_schedule_on_exec_ctx));
-  op->cancel_error = error;
+  op->cancel_stream = true;
+  op->payload->cancel_stream.cancel_error = error;
   execute_op(exec_ctx, c, op);
 }
 
@@ -1025,16 +1034,13 @@ static batch_control *allocate_batch_control(grpc_call *call,
                                              const grpc_op *ops,
                                              size_t num_ops) {
   int slot = batch_slot_for_op(ops[0].op);
-  for (size_t i = 1; i < num_ops; i++) {
-    int op_slot = batch_slot_for_op(ops[i].op);
-    slot = GPR_MIN(slot, op_slot);
-  }
   batch_control *bctl = &call->active_batches[slot];
   if (bctl->call != NULL) {
     return NULL;
   }
   memset(bctl, 0, sizeof(*bctl));
   bctl->call = call;
+  bctl->op.payload = &call->stream_op_payload;
   return bctl;
 }
 
@@ -1074,20 +1080,20 @@ static void post_batch_completion(grpc_exec_ctx *exec_ctx,
   grpc_call *call = bctl->call;
   grpc_error *error = consolidate_batch_errors(bctl);
 
-  if (bctl->send_initial_metadata) {
+  if (bctl->op.send_initial_metadata) {
     grpc_metadata_batch_destroy(
         exec_ctx,
         &call->metadata_batch[0 /* is_receiving */][0 /* is_trailing */]);
   }
-  if (bctl->send_message) {
+  if (bctl->op.send_message) {
     call->sending_message = false;
   }
-  if (bctl->send_final_op) {
+  if (bctl->op.send_trailing_metadata) {
     grpc_metadata_batch_destroy(
         exec_ctx,
         &call->metadata_batch[0 /* is_receiving */][1 /* is_trailing */]);
   }
-  if (bctl->recv_final_op) {
+  if (bctl->op.recv_trailing_metadata) {
     grpc_metadata_batch *md =
         &call->metadata_batch[1 /* is_receiving */][1 /* is_trailing */];
     recv_trailing_filter(exec_ctx, call, md);
@@ -1123,15 +1129,16 @@ static void post_batch_completion(grpc_exec_ctx *exec_ctx,
     error = GRPC_ERROR_NONE;
   }
 
-  if (bctl->is_notify_tag_closure) {
+  if (bctl->completion_data.notify_tag.is_closure) {
     /* unrefs bctl->error */
     bctl->call = NULL;
-    grpc_closure_run(exec_ctx, bctl->notify_tag, error);
+    grpc_closure_run(exec_ctx, bctl->completion_data.notify_tag.tag, error);
     GRPC_CALL_INTERNAL_UNREF(exec_ctx, call, "completion");
   } else {
     /* unrefs bctl->error */
-    grpc_cq_end_op(exec_ctx, bctl->call->cq, bctl->notify_tag, error,
-                   finish_batch_completion, bctl, &bctl->cq_completion);
+    grpc_cq_end_op(
+        exec_ctx, bctl->call->cq, bctl->completion_data.notify_tag.tag, error,
+        finish_batch_completion, bctl, &bctl->completion_data.cq_completion);
   }
 }
 
@@ -1374,11 +1381,13 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
   if (bctl == NULL) {
     return GRPC_CALL_ERROR_TOO_MANY_OPERATIONS;
   }
-  bctl->notify_tag = notify_tag;
-  bctl->is_notify_tag_closure = (uint8_t)(is_notify_tag_closure != 0);
+  bctl->completion_data.notify_tag.tag = notify_tag;
+  bctl->completion_data.notify_tag.is_closure =
+      (uint8_t)(is_notify_tag_closure != 0);
 
-  grpc_transport_stream_op *stream_op = &bctl->op;
-  memset(stream_op, 0, sizeof(*stream_op));
+  grpc_transport_stream_op_batch *stream_op = &bctl->op;
+  grpc_transport_stream_op_batch_payload *stream_op_payload =
+      &call->stream_op_payload;
   stream_op->covered_by_poller = true;
 
   /* rewrite batch ops into a transport op */
@@ -1432,8 +1441,8 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
           error = GRPC_CALL_ERROR_INVALID_METADATA;
           goto done_with_error;
         }
-        bctl->send_initial_metadata = 1;
-        call->sent_initial_metadata = 1;
+        stream_op->send_initial_metadata = true;
+        call->sent_initial_metadata = true;
         if (!prepare_application_metadata(
                 exec_ctx, call, (int)op->data.send_initial_metadata.count,
                 op->data.send_initial_metadata.metadata, 0, call->is_client,
@@ -1443,9 +1452,10 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
         }
         /* TODO(ctiller): just make these the same variable? */
         call->metadata_batch[0][0].deadline = call->send_deadline;
-        stream_op->send_initial_metadata =
+        stream_op_payload->send_initial_metadata.send_initial_metadata =
             &call->metadata_batch[0 /* is_receiving */][0 /* is_trailing */];
-        stream_op->send_initial_metadata_flags = op->flags;
+        stream_op_payload->send_initial_metadata.send_initial_metadata_flags =
+            op->flags;
         break;
       case GRPC_OP_SEND_MESSAGE:
         if (!are_write_flags_valid(op->flags)) {
@@ -1460,8 +1470,8 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
           error = GRPC_CALL_ERROR_TOO_MANY_OPERATIONS;
           goto done_with_error;
         }
-        bctl->send_message = 1;
-        call->sending_message = 1;
+        stream_op->send_message = true;
+        call->sending_message = true;
         grpc_slice_buffer_stream_init(
             &call->sending_stream,
             &op->data.send_message.send_message->data.raw.slice_buffer,
@@ -1473,7 +1483,8 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
             GRPC_COMPRESS_NONE) {
           call->sending_stream.base.flags |= GRPC_WRITE_INTERNAL_COMPRESS;
         }
-        stream_op->send_message = &call->sending_stream.base;
+        stream_op_payload->send_message.send_message =
+            &call->sending_stream.base;
         break;
       case GRPC_OP_SEND_CLOSE_FROM_CLIENT:
         /* Flag validation: currently allow no flags */
@@ -1489,9 +1500,9 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
           error = GRPC_CALL_ERROR_TOO_MANY_OPERATIONS;
           goto done_with_error;
         }
-        bctl->send_final_op = 1;
-        call->sent_final_op = 1;
-        stream_op->send_trailing_metadata =
+        stream_op->send_trailing_metadata = true;
+        call->sent_final_op = true;
+        stream_op_payload->send_trailing_metadata.send_trailing_metadata =
             &call->metadata_batch[0 /* is_receiving */][1 /* is_trailing */];
         break;
       case GRPC_OP_SEND_STATUS_FROM_SERVER:
@@ -1513,8 +1524,8 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
           error = GRPC_CALL_ERROR_INVALID_METADATA;
           goto done_with_error;
         }
-        bctl->send_final_op = 1;
-        call->sent_final_op = 1;
+        stream_op->send_trailing_metadata = true;
+        call->sent_final_op = true;
         GPR_ASSERT(call->send_extra_metadata_count == 0);
         call->send_extra_metadata_count = 1;
         call->send_extra_metadata[0].md = grpc_channel_get_reffed_status_elem(
@@ -1553,7 +1564,7 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
           error = GRPC_CALL_ERROR_INVALID_METADATA;
           goto done_with_error;
         }
-        stream_op->send_trailing_metadata =
+        stream_op_payload->send_trailing_metadata.send_trailing_metadata =
             &call->metadata_batch[0 /* is_receiving */][1 /* is_trailing */];
         break;
       case GRPC_OP_RECV_INITIAL_METADATA:
@@ -1570,16 +1581,16 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
            from server.c. In that case, it's coming from accept_stream, and in
            that case we're not necessarily covered by a poller. */
         stream_op->covered_by_poller = call->is_client;
-        call->received_initial_metadata = 1;
+        call->received_initial_metadata = true;
         call->buffered_metadata[0] =
             op->data.recv_initial_metadata.recv_initial_metadata;
         grpc_closure_init(&call->receiving_initial_metadata_ready,
                           receiving_initial_metadata_ready, bctl,
                           grpc_schedule_on_exec_ctx);
-        bctl->recv_initial_metadata = 1;
-        stream_op->recv_initial_metadata =
+        stream_op->recv_initial_metadata = true;
+        stream_op_payload->recv_initial_metadata.recv_initial_metadata =
             &call->metadata_batch[1 /* is_receiving */][0 /* is_trailing */];
-        stream_op->recv_initial_metadata_ready =
+        stream_op_payload->recv_initial_metadata.recv_initial_metadata_ready =
             &call->receiving_initial_metadata_ready;
         num_completion_callbacks_needed++;
         break;
@@ -1593,13 +1604,14 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
           error = GRPC_CALL_ERROR_TOO_MANY_OPERATIONS;
           goto done_with_error;
         }
-        call->receiving_message = 1;
-        bctl->recv_message = 1;
+        call->receiving_message = true;
+        stream_op->recv_message = true;
         call->receiving_buffer = op->data.recv_message.recv_message;
-        stream_op->recv_message = &call->receiving_stream;
+        stream_op_payload->recv_message.recv_message = &call->receiving_stream;
         grpc_closure_init(&call->receiving_stream_ready, receiving_stream_ready,
                           bctl, grpc_schedule_on_exec_ctx);
-        stream_op->recv_message_ready = &call->receiving_stream_ready;
+        stream_op_payload->recv_message.recv_message_ready =
+            &call->receiving_stream_ready;
         num_completion_callbacks_needed++;
         break;
       case GRPC_OP_RECV_STATUS_ON_CLIENT:
@@ -1616,16 +1628,17 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
           error = GRPC_CALL_ERROR_TOO_MANY_OPERATIONS;
           goto done_with_error;
         }
-        call->requested_final_op = 1;
+        call->requested_final_op = true;
         call->buffered_metadata[1] =
             op->data.recv_status_on_client.trailing_metadata;
         call->final_op.client.status = op->data.recv_status_on_client.status;
         call->final_op.client.status_details =
             op->data.recv_status_on_client.status_details;
-        bctl->recv_final_op = 1;
-        stream_op->recv_trailing_metadata =
+        stream_op->recv_trailing_metadata = true;
+        stream_op->collect_stats = true;
+        stream_op_payload->recv_trailing_metadata.recv_trailing_metadata =
             &call->metadata_batch[1 /* is_receiving */][1 /* is_trailing */];
-        stream_op->collect_stats =
+        stream_op_payload->collect_stats.collect_stats =
             &call->final_info.stats.transport_stream_stats;
         break;
       case GRPC_OP_RECV_CLOSE_ON_SERVER:
@@ -1642,13 +1655,14 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
           error = GRPC_CALL_ERROR_TOO_MANY_OPERATIONS;
           goto done_with_error;
         }
-        call->requested_final_op = 1;
+        call->requested_final_op = true;
         call->final_op.server.cancelled =
             op->data.recv_close_on_server.cancelled;
-        bctl->recv_final_op = 1;
-        stream_op->recv_trailing_metadata =
+        stream_op->recv_trailing_metadata = true;
+        stream_op->collect_stats = true;
+        stream_op_payload->recv_trailing_metadata.recv_trailing_metadata =
             &call->metadata_batch[1 /* is_receiving */][1 /* is_trailing */];
-        stream_op->collect_stats =
+        stream_op_payload->collect_stats.collect_stats =
             &call->final_info.stats.transport_stream_stats;
         break;
     }
@@ -1660,7 +1674,6 @@ static grpc_call_error call_start_batch(grpc_exec_ctx *exec_ctx,
   }
   gpr_ref_init(&bctl->steps_to_complete, num_completion_callbacks_needed);
 
-  stream_op->context = call->context;
   grpc_closure_init(&bctl->finish_batch, finish_batch, bctl,
                     grpc_schedule_on_exec_ctx);
   stream_op->on_complete = &bctl->finish_batch;
@@ -1674,26 +1687,26 @@ done:
 
 done_with_error:
   /* reverse any mutations that occured */
-  if (bctl->send_initial_metadata) {
-    call->sent_initial_metadata = 0;
+  if (stream_op->send_initial_metadata) {
+    call->sent_initial_metadata = false;
     grpc_metadata_batch_clear(exec_ctx, &call->metadata_batch[0][0]);
   }
-  if (bctl->send_message) {
-    call->sending_message = 0;
+  if (stream_op->send_message) {
+    call->sending_message = false;
     grpc_byte_stream_destroy(exec_ctx, &call->sending_stream.base);
   }
-  if (bctl->send_final_op) {
-    call->sent_final_op = 0;
+  if (stream_op->send_trailing_metadata) {
+    call->sent_final_op = false;
     grpc_metadata_batch_clear(exec_ctx, &call->metadata_batch[0][1]);
   }
-  if (bctl->recv_initial_metadata) {
-    call->received_initial_metadata = 0;
+  if (stream_op->recv_initial_metadata) {
+    call->received_initial_metadata = false;
   }
-  if (bctl->recv_message) {
-    call->receiving_message = 0;
+  if (stream_op->recv_message) {
+    call->receiving_message = false;
   }
-  if (bctl->recv_final_op) {
-    call->requested_final_op = 0;
+  if (stream_op->recv_trailing_metadata) {
+    call->requested_final_op = false;
   }
   goto done;
 }
diff --git a/src/core/lib/surface/lame_client.c b/src/core/lib/surface/lame_client.c
index 0c408aa288..82428c42c0 100644
--- a/src/core/lib/surface/lame_client.c
+++ b/src/core/lib/surface/lame_client.c
@@ -80,16 +80,18 @@ static void fill_metadata(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   mdb->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
 }
 
-static void lame_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                           grpc_call_element *elem,
-                                           grpc_transport_stream_op *op) {
+static void lame_start_transport_stream_op_batch(
+    grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+    grpc_transport_stream_op_batch *op) {
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
-  if (op->recv_initial_metadata != NULL) {
-    fill_metadata(exec_ctx, elem, op->recv_initial_metadata);
-  } else if (op->recv_trailing_metadata != NULL) {
-    fill_metadata(exec_ctx, elem, op->recv_trailing_metadata);
+  if (op->recv_initial_metadata) {
+    fill_metadata(exec_ctx, elem,
+                  op->payload->recv_initial_metadata.recv_initial_metadata);
+  } else if (op->recv_trailing_metadata) {
+    fill_metadata(exec_ctx, elem,
+                  op->payload->recv_trailing_metadata.recv_trailing_metadata);
   }
-  grpc_transport_stream_op_finish_with_failure(
+  grpc_transport_stream_op_batch_finish_with_failure(
       exec_ctx, op,
       GRPC_ERROR_CREATE_FROM_STATIC_STRING("lame client channel"));
 }
@@ -148,7 +150,7 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {}
 
 const grpc_channel_filter grpc_lame_filter = {
-    lame_start_transport_stream_op,
+    lame_start_transport_stream_op_batch,
     lame_start_transport_op,
     sizeof(call_data),
     init_call_elem,
diff --git a/src/core/lib/surface/server.c b/src/core/lib/surface/server.c
index a123c9ca43..191ee75252 100644
--- a/src/core/lib/surface/server.c
+++ b/src/core/lib/surface/server.c
@@ -154,8 +154,7 @@ struct call_data {
   grpc_completion_queue *cq_new;
 
   grpc_metadata_batch *recv_initial_metadata;
-  bool recv_idempotent_request;
-  bool recv_cacheable_request;
+  uint32_t recv_initial_metadata_flags;
   grpc_metadata_array initial_metadata;
 
   request_matcher *request_matcher;
@@ -498,13 +497,7 @@ static void publish_call(grpc_exec_ctx *exec_ctx, grpc_server *server,
       rc->data.batch.details->host = grpc_slice_ref_internal(calld->host);
       rc->data.batch.details->method = grpc_slice_ref_internal(calld->path);
       rc->data.batch.details->deadline = calld->deadline;
-      rc->data.batch.details->flags =
-          (calld->recv_idempotent_request
-               ? GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST
-               : 0) |
-          (calld->recv_cacheable_request
-               ? GRPC_INITIAL_METADATA_CACHEABLE_REQUEST
-               : 0);
+      rc->data.batch.details->flags = calld->recv_initial_metadata_flags;
       break;
     case REGISTERED_CALL:
       *rc->data.registered.deadline = calld->deadline;
@@ -632,7 +625,8 @@ static void start_new_rpc(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
       if (!grpc_slice_eq(rm->host, calld->host)) continue;
       if (!grpc_slice_eq(rm->method, calld->path)) continue;
       if ((rm->flags & GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST) &&
-          !calld->recv_idempotent_request) {
+          0 == (calld->recv_initial_metadata_flags &
+                GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST)) {
         continue;
       }
       finish_start_new_rpc(exec_ctx, server, elem,
@@ -649,7 +643,8 @@ static void start_new_rpc(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
       if (rm->has_host) continue;
       if (!grpc_slice_eq(rm->method, calld->path)) continue;
       if ((rm->flags & GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST) &&
-          !calld->recv_idempotent_request) {
+          0 == (calld->recv_initial_metadata_flags &
+                GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST)) {
         continue;
       }
       finish_start_new_rpc(exec_ctx, server, elem,
@@ -781,22 +776,25 @@ static void server_on_recv_initial_metadata(grpc_exec_ctx *exec_ctx, void *ptr,
 }
 
 static void server_mutate_op(grpc_call_element *elem,
-                             grpc_transport_stream_op *op) {
+                             grpc_transport_stream_op_batch *op) {
   call_data *calld = elem->call_data;
 
-  if (op->recv_initial_metadata != NULL) {
-    GPR_ASSERT(op->recv_idempotent_request == NULL);
-    calld->recv_initial_metadata = op->recv_initial_metadata;
-    calld->on_done_recv_initial_metadata = op->recv_initial_metadata_ready;
-    op->recv_initial_metadata_ready = &calld->server_on_recv_initial_metadata;
-    op->recv_idempotent_request = &calld->recv_idempotent_request;
-    op->recv_cacheable_request = &calld->recv_cacheable_request;
+  if (op->recv_initial_metadata) {
+    GPR_ASSERT(op->payload->recv_initial_metadata.recv_flags == NULL);
+    calld->recv_initial_metadata =
+        op->payload->recv_initial_metadata.recv_initial_metadata;
+    calld->on_done_recv_initial_metadata =
+        op->payload->recv_initial_metadata.recv_initial_metadata_ready;
+    op->payload->recv_initial_metadata.recv_initial_metadata_ready =
+        &calld->server_on_recv_initial_metadata;
+    op->payload->recv_initial_metadata.recv_flags =
+        &calld->recv_initial_metadata_flags;
   }
 }
 
-static void server_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                             grpc_call_element *elem,
-                                             grpc_transport_stream_op *op) {
+static void server_start_transport_stream_op_batch(
+    grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+    grpc_transport_stream_op_batch *op) {
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
   server_mutate_op(elem, op);
   grpc_call_next_op(exec_ctx, elem, op);
@@ -960,7 +958,7 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
 }
 
 const grpc_channel_filter grpc_server_top_filter = {
-    server_start_transport_stream_op,
+    server_start_transport_stream_op_batch,
     grpc_channel_next_op,
     sizeof(call_data),
     init_call_elem,
diff --git a/src/core/lib/transport/transport.c b/src/core/lib/transport/transport.c
index d56cb31ee0..82c4e004b7 100644
--- a/src/core/lib/transport/transport.c
+++ b/src/core/lib/transport/transport.c
@@ -170,7 +170,7 @@ int grpc_transport_init_stream(grpc_exec_ctx *exec_ctx,
 void grpc_transport_perform_stream_op(grpc_exec_ctx *exec_ctx,
                                       grpc_transport *transport,
                                       grpc_stream *stream,
-                                      grpc_transport_stream_op *op) {
+                                      grpc_transport_stream_op_batch *op) {
   transport->vtable->perform_stream_op(exec_ctx, transport, stream, op);
 }
 
@@ -213,14 +213,23 @@ grpc_endpoint *grpc_transport_get_endpoint(grpc_exec_ctx *exec_ctx,
   return transport->vtable->get_endpoint(exec_ctx, transport);
 }
 
-void grpc_transport_stream_op_finish_with_failure(grpc_exec_ctx *exec_ctx,
-                                                  grpc_transport_stream_op *op,
-                                                  grpc_error *error) {
-  grpc_closure_sched(exec_ctx, op->recv_message_ready, GRPC_ERROR_REF(error));
-  grpc_closure_sched(exec_ctx, op->recv_initial_metadata_ready,
-                     GRPC_ERROR_REF(error));
+void grpc_transport_stream_op_batch_finish_with_failure(
+    grpc_exec_ctx *exec_ctx, grpc_transport_stream_op_batch *op,
+    grpc_error *error) {
+  if (op->recv_message) {
+    grpc_closure_sched(exec_ctx, op->payload->recv_message.recv_message_ready,
+                       GRPC_ERROR_REF(error));
+  }
+  if (op->recv_initial_metadata) {
+    grpc_closure_sched(
+        exec_ctx,
+        op->payload->recv_initial_metadata.recv_initial_metadata_ready,
+        GRPC_ERROR_REF(error));
+  }
   grpc_closure_sched(exec_ctx, op->on_complete, error);
-  GRPC_ERROR_UNREF(op->cancel_error);
+  if (op->cancel_stream) {
+    GRPC_ERROR_UNREF(op->payload->cancel_stream.cancel_error);
+  }
 }
 
 typedef struct {
@@ -249,7 +258,8 @@ grpc_transport_op *grpc_make_transport_op(grpc_closure *on_complete) {
 typedef struct {
   grpc_closure outer_on_complete;
   grpc_closure *inner_on_complete;
-  grpc_transport_stream_op op;
+  grpc_transport_stream_op_batch op;
+  grpc_transport_stream_op_batch_payload payload;
 } made_transport_stream_op;
 
 static void destroy_made_transport_stream_op(grpc_exec_ctx *exec_ctx, void *arg,
@@ -260,13 +270,13 @@ static void destroy_made_transport_stream_op(grpc_exec_ctx *exec_ctx, void *arg,
   grpc_closure_run(exec_ctx, c, GRPC_ERROR_REF(error));
 }
 
-grpc_transport_stream_op *grpc_make_transport_stream_op(
+grpc_transport_stream_op_batch *grpc_make_transport_stream_op(
     grpc_closure *on_complete) {
-  made_transport_stream_op *op = gpr_malloc(sizeof(*op));
+  made_transport_stream_op *op = gpr_zalloc(sizeof(*op));
+  op->op.payload = &op->payload;
   grpc_closure_init(&op->outer_on_complete, destroy_made_transport_stream_op,
                     op, grpc_schedule_on_exec_ctx);
   op->inner_on_complete = on_complete;
-  memset(&op->op, 0, sizeof(op->op));
   op->op.on_complete = &op->outer_on_complete;
   return &op->op;
 }
diff --git a/src/core/lib/transport/transport.h b/src/core/lib/transport/transport.h
index 950b18aeda..93369cc689 100644
--- a/src/core/lib/transport/transport.h
+++ b/src/core/lib/transport/transport.h
@@ -109,55 +109,98 @@ void grpc_transport_move_stats(grpc_transport_stream_stats *from,
                                grpc_transport_stream_stats *to);
 
 typedef struct {
+  void *extra_arg;
   grpc_closure closure;
-  void *args[2];
-} grpc_transport_private_op_data;
+} grpc_handler_private_op_data;
+
+typedef struct grpc_transport_stream_op_batch_payload
+    grpc_transport_stream_op_batch_payload;
 
 /* Transport stream op: a set of operations to perform on a transport
    against a single stream */
-typedef struct grpc_transport_stream_op {
+typedef struct grpc_transport_stream_op_batch {
   /** Should be enqueued when all requested operations (excluding recv_message
       and recv_initial_metadata which have their own closures) in a given batch
       have been completed. */
   grpc_closure *on_complete;
 
+  /** Values for the stream op (fields set are determined by flags above) */
+  grpc_transport_stream_op_batch_payload *payload;
+
   /** Is the completion of this op covered by a poller (if false: the op should
       complete independently of some pollset being polled) */
-  bool covered_by_poller;
+  bool covered_by_poller : 1;
 
-  /** Send initial metadata to the peer, from the provided metadata batch.
-      idempotent_request MUST be set if this is non-null */
-  grpc_metadata_batch *send_initial_metadata;
-  /** Iff send_initial_metadata != NULL, flags associated with
-      send_initial_metadata: a bitfield of GRPC_INITIAL_METADATA_xxx */
-  uint32_t send_initial_metadata_flags;
+  /** Send initial metadata to the peer, from the provided metadata batch. */
+  bool send_initial_metadata : 1;
 
   /** Send trailing metadata to the peer, from the provided metadata batch. */
-  grpc_metadata_batch *send_trailing_metadata;
+  bool send_trailing_metadata : 1;
 
   /** Send message data to the peer, from the provided byte stream. */
-  grpc_byte_stream *send_message;
+  bool send_message : 1;
 
   /** Receive initial metadata from the stream, into provided metadata batch. */
-  grpc_metadata_batch *recv_initial_metadata;
-  bool *recv_idempotent_request;
-  bool *recv_cacheable_request;
-  /** Should be enqueued when initial metadata is ready to be processed. */
-  grpc_closure *recv_initial_metadata_ready;
+  bool recv_initial_metadata : 1;
 
   /** Receive message data from the stream, into provided byte stream. */
-  grpc_byte_stream **recv_message;
-  /** Should be enqueued when one message is ready to be processed. */
-  grpc_closure *recv_message_ready;
+  bool recv_message : 1;
 
   /** Receive trailing metadata from the stream, into provided metadata batch.
    */
-  grpc_metadata_batch *recv_trailing_metadata;
+  bool recv_trailing_metadata : 1;
 
   /** Collect any stats into provided buffer, zero internal stat counters */
-  grpc_transport_stream_stats *collect_stats;
+  bool collect_stats : 1;
+
+  /** Cancel this stream with the provided error */
+  bool cancel_stream : 1;
+
+  /***************************************************************************
+   * remaining fields are initialized and used at the discretion of the
+   * current handler of the op */
 
-  /** If != GRPC_ERROR_NONE, forcefully close this stream.
+  grpc_handler_private_op_data handler_private;
+} grpc_transport_stream_op_batch;
+
+struct grpc_transport_stream_op_batch_payload {
+  struct {
+    grpc_metadata_batch *send_initial_metadata;
+    /** Iff send_initial_metadata != NULL, flags associated with
+        send_initial_metadata: a bitfield of GRPC_INITIAL_METADATA_xxx */
+    uint32_t send_initial_metadata_flags;
+  } send_initial_metadata;
+
+  struct {
+    grpc_metadata_batch *send_trailing_metadata;
+  } send_trailing_metadata;
+
+  struct {
+    grpc_byte_stream *send_message;
+  } send_message;
+
+  struct {
+    grpc_metadata_batch *recv_initial_metadata;
+    uint32_t *recv_flags;
+    /** Should be enqueued when initial metadata is ready to be processed. */
+    grpc_closure *recv_initial_metadata_ready;
+  } recv_initial_metadata;
+
+  struct {
+    grpc_byte_stream **recv_message;
+    /** Should be enqueued when one message is ready to be processed. */
+    grpc_closure *recv_message_ready;
+  } recv_message;
+
+  struct {
+    grpc_metadata_batch *recv_trailing_metadata;
+  } recv_trailing_metadata;
+
+  struct {
+    grpc_transport_stream_stats *collect_stats;
+  } collect_stats;
+
+  /** Forcefully close this stream.
       The HTTP2 semantics should be:
       - server side: if cancel_error has GRPC_ERROR_INT_GRPC_STATUS, and
         trailing metadata has not been sent, send trailing metadata with status
@@ -167,17 +210,13 @@ typedef struct grpc_transport_stream_op {
         convert to a HTTP2 error code using
         grpc_chttp2_grpc_status_to_http2_error. Send a RST_STREAM with this
         error. */
-  grpc_error *cancel_error;
+  struct {
+    grpc_error *cancel_error;
+  } cancel_stream;
 
   /* Indexes correspond to grpc_context_index enum values */
   grpc_call_context_element *context;
-
-  /***************************************************************************
-   * remaining fields are initialized and used at the discretion of the
-   * current handler of the op */
-
-  grpc_transport_private_op_data handler_private;
-} grpc_transport_stream_op;
+};
 
 /** Transport op: a set of operations to perform on a transport as a whole */
 typedef struct grpc_transport_op {
@@ -210,7 +249,7 @@ typedef struct grpc_transport_op {
    * remaining fields are initialized and used at the discretion of the
    * transport implementation */
 
-  grpc_transport_private_op_data transport_private;
+  grpc_handler_private_op_data handler_private;
 } grpc_transport_op;
 
 /* Returns the amount of memory required to store a grpc_stream for this
@@ -250,11 +289,11 @@ void grpc_transport_destroy_stream(grpc_exec_ctx *exec_ctx,
                                    grpc_stream *stream,
                                    grpc_closure *then_schedule_closure);
 
-void grpc_transport_stream_op_finish_with_failure(grpc_exec_ctx *exec_ctx,
-                                                  grpc_transport_stream_op *op,
-                                                  grpc_error *error);
+void grpc_transport_stream_op_batch_finish_with_failure(
+    grpc_exec_ctx *exec_ctx, grpc_transport_stream_op_batch *op,
+    grpc_error *error);
 
-char *grpc_transport_stream_op_string(grpc_transport_stream_op *op);
+char *grpc_transport_stream_op_batch_string(grpc_transport_stream_op_batch *op);
 char *grpc_transport_op_string(grpc_transport_op *op);
 
 /* Send a batch of operations on a transport
@@ -265,11 +304,12 @@ char *grpc_transport_op_string(grpc_transport_op *op);
      transport - the transport on which to initiate the stream
      stream    - the stream on which to send the operations. This must be
                  non-NULL and previously initialized by the same transport.
-     op        - a grpc_transport_stream_op specifying the op to perform */
+     op        - a grpc_transport_stream_op_batch specifying the op to perform
+   */
 void grpc_transport_perform_stream_op(grpc_exec_ctx *exec_ctx,
                                       grpc_transport *transport,
                                       grpc_stream *stream,
-                                      grpc_transport_stream_op *op);
+                                      grpc_transport_stream_op_batch *op);
 
 void grpc_transport_perform_op(grpc_exec_ctx *exec_ctx,
                                grpc_transport *transport,
@@ -301,9 +341,10 @@ grpc_endpoint *grpc_transport_get_endpoint(grpc_exec_ctx *exec_ctx,
 /* Allocate a grpc_transport_op, and preconfigure the on_consumed closure to
    \a on_consumed and then delete the returned transport op */
 grpc_transport_op *grpc_make_transport_op(grpc_closure *on_consumed);
-/* Allocate a grpc_transport_stream_op, and preconfigure the on_consumed closure
+/* Allocate a grpc_transport_stream_op_batch, and preconfigure the on_consumed
+   closure
    to \a on_consumed and then delete the returned transport op */
-grpc_transport_stream_op *grpc_make_transport_stream_op(
+grpc_transport_stream_op_batch *grpc_make_transport_stream_op(
     grpc_closure *on_consumed);
 
 #ifdef __cplusplus
diff --git a/src/core/lib/transport/transport_impl.h b/src/core/lib/transport/transport_impl.h
index 6f688bf8d2..bbb19a34bd 100644
--- a/src/core/lib/transport/transport_impl.h
+++ b/src/core/lib/transport/transport_impl.h
@@ -59,7 +59,8 @@ typedef struct grpc_transport_vtable {
 
   /* implementation of grpc_transport_perform_stream_op */
   void (*perform_stream_op)(grpc_exec_ctx *exec_ctx, grpc_transport *self,
-                            grpc_stream *stream, grpc_transport_stream_op *op);
+                            grpc_stream *stream,
+                            grpc_transport_stream_op_batch *op);
 
   /* implementation of grpc_transport_perform_op */
   void (*perform_op)(grpc_exec_ctx *exec_ctx, grpc_transport *self,
diff --git a/src/core/lib/transport/transport_op_string.c b/src/core/lib/transport/transport_op_string.c
index 28360e3784..3a2a793e01 100644
--- a/src/core/lib/transport/transport_op_string.c
+++ b/src/core/lib/transport/transport_op_string.c
@@ -71,7 +71,8 @@ static void put_metadata_list(gpr_strvec *b, grpc_metadata_batch md) {
   }
 }
 
-char *grpc_transport_stream_op_string(grpc_transport_stream_op *op) {
+char *grpc_transport_stream_op_batch_string(
+    grpc_transport_stream_op_batch *op) {
   char *tmp;
   char *out;
 
@@ -81,45 +82,49 @@ char *grpc_transport_stream_op_string(grpc_transport_stream_op *op) {
   gpr_strvec_add(
       &b, gpr_strdup(op->covered_by_poller ? "[COVERED]" : "[UNCOVERED]"));
 
-  if (op->send_initial_metadata != NULL) {
+  if (op->send_initial_metadata) {
     gpr_strvec_add(&b, gpr_strdup(" "));
     gpr_strvec_add(&b, gpr_strdup("SEND_INITIAL_METADATA{"));
-    put_metadata_list(&b, *op->send_initial_metadata);
+    put_metadata_list(
+        &b, *op->payload->send_initial_metadata.send_initial_metadata);
     gpr_strvec_add(&b, gpr_strdup("}"));
   }
 
-  if (op->send_message != NULL) {
+  if (op->send_message) {
     gpr_strvec_add(&b, gpr_strdup(" "));
     gpr_asprintf(&tmp, "SEND_MESSAGE:flags=0x%08x:len=%d",
-                 op->send_message->flags, op->send_message->length);
+                 op->payload->send_message.send_message->flags,
+                 op->payload->send_message.send_message->length);
     gpr_strvec_add(&b, tmp);
   }
 
-  if (op->send_trailing_metadata != NULL) {
+  if (op->send_trailing_metadata) {
     gpr_strvec_add(&b, gpr_strdup(" "));
     gpr_strvec_add(&b, gpr_strdup("SEND_TRAILING_METADATA{"));
-    put_metadata_list(&b, *op->send_trailing_metadata);
+    put_metadata_list(
+        &b, *op->payload->send_trailing_metadata.send_trailing_metadata);
     gpr_strvec_add(&b, gpr_strdup("}"));
   }
 
-  if (op->recv_initial_metadata != NULL) {
+  if (op->recv_initial_metadata) {
     gpr_strvec_add(&b, gpr_strdup(" "));
     gpr_strvec_add(&b, gpr_strdup("RECV_INITIAL_METADATA"));
   }
 
-  if (op->recv_message != NULL) {
+  if (op->recv_message) {
     gpr_strvec_add(&b, gpr_strdup(" "));
     gpr_strvec_add(&b, gpr_strdup("RECV_MESSAGE"));
   }
 
-  if (op->recv_trailing_metadata != NULL) {
+  if (op->recv_trailing_metadata) {
     gpr_strvec_add(&b, gpr_strdup(" "));
     gpr_strvec_add(&b, gpr_strdup("RECV_TRAILING_METADATA"));
   }
 
-  if (op->cancel_error != GRPC_ERROR_NONE) {
+  if (op->cancel_stream) {
     gpr_strvec_add(&b, gpr_strdup(" "));
-    const char *msg = grpc_error_string(op->cancel_error);
+    const char *msg =
+        grpc_error_string(op->payload->cancel_stream.cancel_error);
     gpr_asprintf(&tmp, "CANCEL:%s", msg);
 
     gpr_strvec_add(&b, tmp);
@@ -204,8 +209,9 @@ char *grpc_transport_op_string(grpc_transport_op *op) {
 }
 
 void grpc_call_log_op(char *file, int line, gpr_log_severity severity,
-                      grpc_call_element *elem, grpc_transport_stream_op *op) {
-  char *str = grpc_transport_stream_op_string(op);
+                      grpc_call_element *elem,
+                      grpc_transport_stream_op_batch *op) {
+  char *str = grpc_transport_stream_op_batch_string(op);
   gpr_log(file, line, severity, "OP[%s:%p]: %s", elem->filter->name, elem, str);
   gpr_free(str);
 }
diff --git a/src/cpp/common/channel_filter.cc b/src/cpp/common/channel_filter.cc
index 253614ca9b..a7b3c2c0da 100644
--- a/src/cpp/common/channel_filter.cc
+++ b/src/cpp/common/channel_filter.cc
@@ -69,9 +69,9 @@ void ChannelData::GetInfo(grpc_exec_ctx *exec_ctx, grpc_channel_element *elem,
 
 // CallData
 
-void CallData::StartTransportStreamOp(grpc_exec_ctx *exec_ctx,
-                                      grpc_call_element *elem,
-                                      TransportStreamOp *op) {
+void CallData::StartTransportStreamOpBatch(grpc_exec_ctx *exec_ctx,
+                                           grpc_call_element *elem,
+                                           TransportStreamOpBatch *op) {
   grpc_call_next_op(exec_ctx, elem, op->op());
 }
 
diff --git a/src/cpp/common/channel_filter.h b/src/cpp/common/channel_filter.h
index 7bdb9b3de9..8d800b87d9 100644
--- a/src/cpp/common/channel_filter.h
+++ b/src/cpp/common/channel_filter.h
@@ -140,63 +140,80 @@ class TransportOp {
   grpc_transport_op *op_;  // Not owned.
 };
 
-/// A C++ wrapper for the \c grpc_transport_stream_op struct.
-class TransportStreamOp {
+/// A C++ wrapper for the \c grpc_transport_stream_op_batch struct.
+class TransportStreamOpBatch {
  public:
   /// Borrows a pointer to \a op, but does NOT take ownership.
   /// The caller must ensure that \a op continues to exist for as
-  /// long as the TransportStreamOp object does.
-  explicit TransportStreamOp(grpc_transport_stream_op *op)
+  /// long as the TransportStreamOpBatch object does.
+  explicit TransportStreamOpBatch(grpc_transport_stream_op_batch *op)
       : op_(op),
-        send_initial_metadata_(op->send_initial_metadata),
-        send_trailing_metadata_(op->send_trailing_metadata),
-        recv_initial_metadata_(op->recv_initial_metadata),
-        recv_trailing_metadata_(op->recv_trailing_metadata) {}
-
-  grpc_transport_stream_op *op() const { return op_; }
+        send_initial_metadata_(
+            op->send_initial_metadata
+                ? op->payload->send_initial_metadata.send_initial_metadata
+                : nullptr),
+        send_trailing_metadata_(
+            op->send_trailing_metadata
+                ? op->payload->send_trailing_metadata.send_trailing_metadata
+                : nullptr),
+        recv_initial_metadata_(
+            op->recv_initial_metadata
+                ? op->payload->recv_initial_metadata.recv_initial_metadata
+                : nullptr),
+        recv_trailing_metadata_(
+            op->recv_trailing_metadata
+                ? op->payload->recv_trailing_metadata.recv_trailing_metadata
+                : nullptr) {}
+
+  grpc_transport_stream_op_batch *op() const { return op_; }
 
   grpc_closure *on_complete() const { return op_->on_complete; }
   void set_on_complete(grpc_closure *closure) { op_->on_complete = closure; }
 
   MetadataBatch *send_initial_metadata() {
-    return op_->send_initial_metadata == nullptr ? nullptr
-                                                 : &send_initial_metadata_;
+    return op_->send_initial_metadata ? &send_initial_metadata_ : nullptr;
   }
   MetadataBatch *send_trailing_metadata() {
-    return op_->send_trailing_metadata == nullptr ? nullptr
-                                                  : &send_trailing_metadata_;
+    return op_->send_trailing_metadata ? &send_trailing_metadata_ : nullptr;
   }
   MetadataBatch *recv_initial_metadata() {
-    return op_->recv_initial_metadata == nullptr ? nullptr
-                                                 : &recv_initial_metadata_;
+    return op_->recv_initial_metadata ? &recv_initial_metadata_ : nullptr;
   }
   MetadataBatch *recv_trailing_metadata() {
-    return op_->recv_trailing_metadata == nullptr ? nullptr
-                                                  : &recv_trailing_metadata_;
+    return op_->recv_trailing_metadata ? &recv_trailing_metadata_ : nullptr;
   }
 
   uint32_t *send_initial_metadata_flags() const {
-    return &op_->send_initial_metadata_flags;
+    return op_->send_initial_metadata
+               ? &op_->payload->send_initial_metadata
+                      .send_initial_metadata_flags
+               : nullptr;
   }
 
   grpc_closure *recv_initial_metadata_ready() const {
-    return op_->recv_initial_metadata_ready;
+    return op_->recv_initial_metadata
+               ? op_->payload->recv_initial_metadata.recv_initial_metadata_ready
+               : nullptr;
   }
   void set_recv_initial_metadata_ready(grpc_closure *closure) {
-    op_->recv_initial_metadata_ready = closure;
+    op_->payload->recv_initial_metadata.recv_initial_metadata_ready = closure;
   }
 
-  grpc_byte_stream *send_message() const { return op_->send_message; }
+  grpc_byte_stream *send_message() const {
+    return op_->send_message ? op_->payload->send_message.send_message
+                             : nullptr;
+  }
   void set_send_message(grpc_byte_stream *send_message) {
-    op_->send_message = send_message;
+    op_->send_message = true;
+    op_->payload->send_message.send_message = send_message;
   }
 
   census_context *get_census_context() const {
-    return (census_context *)op_->context[GRPC_CONTEXT_TRACING].value;
+    return (census_context *)op_->payload->context[GRPC_CONTEXT_TRACING].value;
   }
 
  private:
-  grpc_transport_stream_op *op_;  // Not owned.
+  grpc_transport_stream_op_batch *op_;  // Not owned.
   MetadataBatch send_initial_metadata_;
   MetadataBatch send_trailing_metadata_;
   MetadataBatch recv_initial_metadata_;
@@ -240,9 +257,9 @@ class CallData {
   // TODO(roth): Find a way to avoid passing elem into these methods.
 
   /// Starts a new stream operation.
-  virtual void StartTransportStreamOp(grpc_exec_ctx *exec_ctx,
-                                      grpc_call_element *elem,
-                                      TransportStreamOp *op);
+  virtual void StartTransportStreamOpBatch(grpc_exec_ctx *exec_ctx,
+                                           grpc_call_element *elem,
+                                           TransportStreamOpBatch *op);
 
   /// Sets a pollset or pollset set.
   virtual void SetPollsetOrPollsetSet(grpc_exec_ctx *exec_ctx,
@@ -312,12 +329,12 @@ class ChannelFilter final {
     reinterpret_cast<CallDataType *>(elem->call_data)->~CallDataType();
   }
 
-  static void StartTransportStreamOp(grpc_exec_ctx *exec_ctx,
-                                     grpc_call_element *elem,
-                                     grpc_transport_stream_op *op) {
+  static void StartTransportStreamOpBatch(grpc_exec_ctx *exec_ctx,
+                                          grpc_call_element *elem,
+                                          grpc_transport_stream_op_batch *op) {
     CallDataType *call_data = (CallDataType *)elem->call_data;
-    TransportStreamOp op_wrapper(op);
-    call_data->StartTransportStreamOp(exec_ctx, elem, &op_wrapper);
+    TransportStreamOpBatch op_wrapper(op);
+    call_data->StartTransportStreamOpBatch(exec_ctx, elem, &op_wrapper);
   }
 
   static void SetPollsetOrPollsetSet(grpc_exec_ctx *exec_ctx,
@@ -369,7 +386,7 @@ void RegisterChannelFilter(
       stack_type,
       priority,
       include_filter,
-      {FilterType::StartTransportStreamOp, FilterType::StartTransportOp,
+      {FilterType::StartTransportStreamOpBatch, FilterType::StartTransportOp,
        FilterType::call_data_size, FilterType::InitCallElement,
        FilterType::SetPollsetOrPollsetSet, FilterType::DestroyCallElement,
        FilterType::channel_data_size, FilterType::InitChannelElement,
diff --git a/src/proto/grpc/testing/control.proto b/src/proto/grpc/testing/control.proto
index 8f0d25c2c9..acee86678d 100644
--- a/src/proto/grpc/testing/control.proto
+++ b/src/proto/grpc/testing/control.proto
@@ -113,6 +113,9 @@ message ClientConfig {
   string other_client_api = 15;
 
   repeated ChannelArg channel_args = 16;
+
+  // Number of messages on a stream before it gets finished/restarted
+  int32 messages_per_stream = 18;
 }
 
 message ClientStatus { ClientStats stats = 1; }
diff --git a/test/core/channel/channel_stack_test.c b/test/core/channel/channel_stack_test.c
index af551c4928..4be89c78b5 100644
--- a/test/core/channel/channel_stack_test.c
+++ b/test/core/channel/channel_stack_test.c
@@ -73,7 +73,7 @@ static void call_destroy_func(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 }
 
 static void call_func(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                      grpc_transport_stream_op *op) {
+                      grpc_transport_stream_op_batch *op) {
   ++*(int *)(elem->call_data);
 }
 
diff --git a/test/core/end2end/tests/filter_causes_close.c b/test/core/end2end/tests/filter_causes_close.c
index e6b02eaeee..62bf20809c 100644
--- a/test/core/end2end/tests/filter_causes_close.c
+++ b/test/core/end2end/tests/filter_causes_close.c
@@ -216,13 +216,14 @@ static void recv_im_ready(grpc_exec_ctx *exec_ctx, void *arg,
                          GRPC_STATUS_PERMISSION_DENIED));
 }
 
-static void start_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                      grpc_call_element *elem,
-                                      grpc_transport_stream_op *op) {
+static void start_transport_stream_op_batch(
+    grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+    grpc_transport_stream_op_batch *op) {
   call_data *calld = elem->call_data;
-  if (op->recv_initial_metadata != NULL) {
-    calld->recv_im_ready = op->recv_initial_metadata_ready;
-    op->recv_initial_metadata_ready =
+  if (op->recv_initial_metadata) {
+    calld->recv_im_ready =
+        op->payload->recv_initial_metadata.recv_initial_metadata_ready;
+    op->payload->recv_initial_metadata.recv_initial_metadata_ready =
         grpc_closure_create(recv_im_ready, elem, grpc_schedule_on_exec_ctx);
   }
   grpc_call_next_op(exec_ctx, elem, op);
@@ -248,7 +249,7 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {}
 
 static const grpc_channel_filter test_filter = {
-    start_transport_stream_op,
+    start_transport_stream_op_batch,
     grpc_channel_next_op,
     sizeof(call_data),
     init_call_elem,
diff --git a/test/core/end2end/tests/max_connection_age.c b/test/core/end2end/tests/max_connection_age.c
index 1de54e0825..59bfdbabb9 100644
--- a/test/core/end2end/tests/max_connection_age.c
+++ b/test/core/end2end/tests/max_connection_age.c
@@ -57,7 +57,7 @@
    should be shorter than CALL_DEADLINE_S - CQ_MAX_CONNECTION_AGE_WAIT_TIME_S */
 #define CQ_MAX_CONNECTION_AGE_GRACE_WAIT_TIME_S 2
 /* The grace period for the test to observe the channel shutdown process */
-#define IMMEDIATE_SHUTDOWN_GRACE_TIME_MS 300
+#define IMMEDIATE_SHUTDOWN_GRACE_TIME_MS 3000
 
 static void *tag(intptr_t t) { return (void *)t; }
 
diff --git a/test/core/end2end/tests/max_connection_idle.c b/test/core/end2end/tests/max_connection_idle.c
index 9dc1ee4766..c0984e4d14 100644
--- a/test/core/end2end/tests/max_connection_idle.c
+++ b/test/core/end2end/tests/max_connection_idle.c
@@ -89,8 +89,8 @@ static void test_max_connection_idle(grpc_end2end_test_config config) {
   /* wait for the channel to reach its maximum idle time */
   grpc_channel_watch_connectivity_state(
       f.client, GRPC_CHANNEL_READY,
-      grpc_timeout_milliseconds_to_deadline(MAX_CONNECTION_IDLE_MS + 500), f.cq,
-      tag(99));
+      grpc_timeout_milliseconds_to_deadline(MAX_CONNECTION_IDLE_MS + 3000),
+      f.cq, tag(99));
   CQ_EXPECT_COMPLETION(cqv, tag(99), 1);
   cq_verify(cqv);
   state = grpc_channel_check_connectivity_state(f.client, 0);
diff --git a/test/core/iomgr/timer_heap_test.c b/test/core/iomgr/timer_heap_test.c
index 410d972313..153304fa7b 100644
--- a/test/core/iomgr/timer_heap_test.c
+++ b/test/core/iomgr/timer_heap_test.c
@@ -47,13 +47,7 @@
 
 #include "test/core/util/test_config.h"
 
-static gpr_timespec random_deadline(void) {
-  gpr_timespec ts;
-  ts.tv_sec = rand();
-  ts.tv_nsec = rand();
-  ts.clock_type = GPR_CLOCK_REALTIME;
-  return ts;
-}
+static gpr_atm random_deadline(void) { return rand(); }
 
 static grpc_timer *create_test_elements(size_t num_elements) {
   grpc_timer *elems = gpr_malloc(num_elements * sizeof(grpc_timer));
@@ -78,12 +72,10 @@ static void check_valid(grpc_timer_heap *pq) {
     size_t left_child = 1u + 2u * i;
     size_t right_child = left_child + 1u;
     if (left_child < pq->timer_count) {
-      GPR_ASSERT(gpr_time_cmp(pq->timers[i]->deadline,
-                              pq->timers[left_child]->deadline) <= 0);
+      GPR_ASSERT(pq->timers[i]->deadline <= pq->timers[left_child]->deadline);
     }
     if (right_child < pq->timer_count) {
-      GPR_ASSERT(gpr_time_cmp(pq->timers[i]->deadline,
-                              pq->timers[right_child]->deadline) <= 0);
+      GPR_ASSERT(pq->timers[i]->deadline <= pq->timers[right_child]->deadline);
     }
   }
 }
@@ -227,20 +219,19 @@ static void test2(void) {
     }
 
     if (num_inserted) {
-      gpr_timespec *min_deadline = NULL;
+      gpr_atm *min_deadline = NULL;
       for (size_t i = 0; i < elems_size; i++) {
         if (elems[i].inserted) {
           if (min_deadline == NULL) {
             min_deadline = &elems[i].elem.deadline;
           } else {
-            if (gpr_time_cmp(elems[i].elem.deadline, *min_deadline) < 0) {
+            if (elems[i].elem.deadline < *min_deadline) {
               min_deadline = &elems[i].elem.deadline;
             }
           }
         }
       }
-      GPR_ASSERT(
-          0 == gpr_time_cmp(grpc_timer_heap_top(&pq)->deadline, *min_deadline));
+      GPR_ASSERT(grpc_timer_heap_top(&pq)->deadline == *min_deadline);
     }
   }
 
diff --git a/test/core/iomgr/timer_list_test.c b/test/core/iomgr/timer_list_test.c
index 85ad5277cc..46e41dd449 100644
--- a/test/core/iomgr/timer_list_test.c
+++ b/test/core/iomgr/timer_list_test.c
@@ -45,6 +45,9 @@
 
 #define MAX_CB 30
 
+extern int grpc_timer_trace;
+extern int grpc_timer_check_trace;
+
 static int cb_called[MAX_CB][2];
 
 static void cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
@@ -57,7 +60,11 @@ static void add_test(void) {
   grpc_timer timers[20];
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
 
+  gpr_log(GPR_INFO, "add_test");
+
   grpc_timer_list_init(start);
+  grpc_timer_trace = 1;
+  grpc_timer_check_trace = 1;
   memset(cb_called, 0, sizeof(cb_called));
 
   /* 10 ms timers.  will expire in the current epoch */
@@ -120,9 +127,7 @@ static void add_test(void) {
 }
 
 static gpr_timespec tfm(int m) {
-  gpr_timespec t = gpr_time_from_millis(m, GPR_TIMESPAN);
-  t.clock_type = GPR_CLOCK_REALTIME;
-  return t;
+  return gpr_time_from_millis(m, GPR_CLOCK_REALTIME);
 }
 
 /* Cleaning up a list with pending timers. */
@@ -130,7 +135,11 @@ void destruction_test(void) {
   grpc_timer timers[5];
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
 
+  gpr_log(GPR_INFO, "destruction_test");
+
   grpc_timer_list_init(gpr_time_0(GPR_CLOCK_REALTIME));
+  grpc_timer_trace = 1;
+  grpc_timer_check_trace = 1;
   memset(cb_called, 0, sizeof(cb_called));
 
   grpc_timer_init(
@@ -170,6 +179,7 @@ void destruction_test(void) {
 
 int main(int argc, char **argv) {
   grpc_test_init(argc, argv);
+  gpr_set_log_verbosity(GPR_LOG_SEVERITY_DEBUG);
   add_test();
   destruction_test();
   return 0;
diff --git a/test/core/support/arena_test.c b/test/core/support/arena_test.c
index 35b2bbd1b1..9eba8a0fa6 100644
--- a/test/core/support/arena_test.c
+++ b/test/core/support/arena_test.c
@@ -83,9 +83,13 @@ static void test(const char *name, size_t init_size, const size_t *allocs,
   static const size_t allocs_##name[] = {__VA_ARGS__}; \
   test(#name, init_size, allocs_##name, GPR_ARRAY_SIZE(allocs_##name))
 
-#define CONCURRENT_TEST_ITERATIONS 100000
 #define CONCURRENT_TEST_THREADS 100
 
+size_t concurrent_test_iterations() {
+  if (sizeof(void *) < 8) return 1000;
+  return 100000;
+}
+
 typedef struct {
   gpr_event ev_start;
   gpr_arena *arena;
@@ -94,7 +98,7 @@ typedef struct {
 static void concurrent_test_body(void *arg) {
   concurrent_test_args *a = arg;
   gpr_event_wait(&a->ev_start, gpr_inf_future(GPR_CLOCK_REALTIME));
-  for (size_t i = 0; i < CONCURRENT_TEST_ITERATIONS; i++) {
+  for (size_t i = 0; i < concurrent_test_iterations(); i++) {
     *(char *)gpr_arena_alloc(a->arena, 1) = (char)i;
   }
 }
diff --git a/test/cpp/end2end/filter_end2end_test.cc b/test/cpp/end2end/filter_end2end_test.cc
index bd384f68b4..2f873eeaa8 100644
--- a/test/cpp/end2end/filter_end2end_test.cc
+++ b/test/cpp/end2end/filter_end2end_test.cc
@@ -122,8 +122,9 @@ class ChannelDataImpl : public ChannelData {
 
 class CallDataImpl : public CallData {
  public:
-  void StartTransportStreamOp(grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
-                              TransportStreamOp* op) override {
+  void StartTransportStreamOpBatch(grpc_exec_ctx* exec_ctx,
+                                   grpc_call_element* elem,
+                                   TransportStreamOpBatch* op) override {
     // Incrementing the counter could be done from Init(), but we want
     // to test that the individual methods are actually called correctly.
     if (op->recv_initial_metadata() != nullptr) IncrementCallCounter();
diff --git a/test/cpp/microbenchmarks/bm_call_create.cc b/test/cpp/microbenchmarks/bm_call_create.cc
index 0c2b170dc2..cc37f0c9e9 100644
--- a/test/cpp/microbenchmarks/bm_call_create.cc
+++ b/test/cpp/microbenchmarks/bm_call_create.cc
@@ -221,7 +221,7 @@ namespace dummy_filter {
 
 static void StartTransportStreamOp(grpc_exec_ctx *exec_ctx,
                                    grpc_call_element *elem,
-                                   grpc_transport_stream_op *op) {}
+                                   grpc_transport_stream_op_batch *op) {}
 
 static void StartTransportOp(grpc_exec_ctx *exec_ctx,
                              grpc_channel_element *elem,
@@ -296,7 +296,7 @@ void SetPollsetSet(grpc_exec_ctx *exec_ctx, grpc_transport *self,
 
 /* implementation of grpc_transport_perform_stream_op */
 void PerformStreamOp(grpc_exec_ctx *exec_ctx, grpc_transport *self,
-                     grpc_stream *stream, grpc_transport_stream_op *op) {
+                     grpc_stream *stream, grpc_transport_stream_op_batch *op) {
   grpc_closure_sched(exec_ctx, op->on_complete, GRPC_ERROR_NONE);
 }
 
@@ -346,13 +346,15 @@ class SendEmptyMetadata {
     memset(&op_, 0, sizeof(op_));
     op_.on_complete = grpc_closure_init(&closure_, DoNothing, nullptr,
                                         grpc_schedule_on_exec_ctx);
+    op_.send_initial_metadata = true;
+    op_.payload = &op_payload_;
   }
 
   class Op {
    public:
     Op(grpc_exec_ctx *exec_ctx, SendEmptyMetadata *p, grpc_call_stack *s) {
       grpc_metadata_batch_init(&batch_);
-      p->op_.send_initial_metadata = &batch_;
+      p->op_payload_.send_initial_metadata.send_initial_metadata = &batch_;
     }
     void Finish(grpc_exec_ctx *exec_ctx) {
       grpc_metadata_batch_destroy(exec_ctx, &batch_);
@@ -366,7 +368,8 @@ class SendEmptyMetadata {
   const gpr_timespec deadline_ = gpr_inf_future(GPR_CLOCK_MONOTONIC);
   const gpr_timespec start_time_ = gpr_now(GPR_CLOCK_MONOTONIC);
   const grpc_slice method_ = grpc_slice_from_static_string("/foo/bar");
-  grpc_transport_stream_op op_;
+  grpc_transport_stream_op_batch op_;
+  grpc_transport_stream_op_batch_payload op_payload_;
   grpc_closure closure_;
 };
 
@@ -488,13 +491,16 @@ namespace isolated_call_filter {
 
 static void StartTransportStreamOp(grpc_exec_ctx *exec_ctx,
                                    grpc_call_element *elem,
-                                   grpc_transport_stream_op *op) {
+                                   grpc_transport_stream_op_batch *op) {
   if (op->recv_initial_metadata) {
-    grpc_closure_sched(exec_ctx, op->recv_initial_metadata_ready,
-                       GRPC_ERROR_NONE);
+    grpc_closure_sched(
+        exec_ctx,
+        op->payload->recv_initial_metadata.recv_initial_metadata_ready,
+        GRPC_ERROR_NONE);
   }
   if (op->recv_message) {
-    grpc_closure_sched(exec_ctx, op->recv_message_ready, GRPC_ERROR_NONE);
+    grpc_closure_sched(exec_ctx, op->payload->recv_message.recv_message_ready,
+                       GRPC_ERROR_NONE);
   }
   grpc_closure_sched(exec_ctx, op->on_complete, GRPC_ERROR_NONE);
 }
diff --git a/test/cpp/microbenchmarks/bm_chttp2_transport.cc b/test/cpp/microbenchmarks/bm_chttp2_transport.cc
index 254d57de20..c89f349ca7 100644
--- a/test/cpp/microbenchmarks/bm_chttp2_transport.cc
+++ b/test/cpp/microbenchmarks/bm_chttp2_transport.cc
@@ -207,7 +207,7 @@ class Stream {
                                   static_cast<grpc_stream *>(stream_), closure);
   }
 
-  void Op(grpc_transport_stream_op *op) {
+  void Op(grpc_transport_stream_op_batch *op) {
     grpc_transport_perform_stream_op(f_->exec_ctx(), f_->transport(),
                                      static_cast<grpc_stream *>(stream_), op);
   }
@@ -305,10 +305,16 @@ static void BM_StreamCreateSendInitialMetadataDestroy(benchmark::State &state) {
   TrackCounters track_counters;
   Fixture f(grpc::ChannelArguments(), true);
   Stream s(&f);
-  grpc_transport_stream_op op;
+  grpc_transport_stream_op_batch op;
+  grpc_transport_stream_op_batch_payload op_payload;
   std::unique_ptr<Closure> start;
   std::unique_ptr<Closure> done;
 
+  auto reset_op = [&]() {
+    memset(&op, 0, sizeof(op));
+    op.payload = &op_payload;
+  };
+
   grpc_metadata_batch b;
   grpc_metadata_batch_init(&b);
   b.deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);
@@ -324,14 +330,16 @@ static void BM_StreamCreateSendInitialMetadataDestroy(benchmark::State &state) {
   start = MakeClosure([&](grpc_exec_ctx *exec_ctx, grpc_error *error) {
     if (!state.KeepRunning()) return;
     s.Init(state);
-    memset(&op, 0, sizeof(op));
+    reset_op();
     op.on_complete = done.get();
-    op.send_initial_metadata = &b;
+    op.send_initial_metadata = true;
+    op.payload->send_initial_metadata.send_initial_metadata = &b;
     s.Op(&op);
   });
   done = MakeClosure([&](grpc_exec_ctx *exec_ctx, grpc_error *error) {
-    memset(&op, 0, sizeof(op));
-    op.cancel_error = GRPC_ERROR_CANCELLED;
+    reset_op();
+    op.cancel_stream = true;
+    op.payload->cancel_stream.cancel_error = GRPC_ERROR_CANCELLED;
     s.Op(&op);
     s.DestroyThen(start.get());
   });
@@ -348,11 +356,16 @@ static void BM_TransportEmptyOp(benchmark::State &state) {
   Fixture f(grpc::ChannelArguments(), true);
   Stream s(&f);
   s.Init(state);
-  grpc_transport_stream_op op;
+  grpc_transport_stream_op_batch op;
+  grpc_transport_stream_op_batch_payload op_payload;
+  auto reset_op = [&]() {
+    memset(&op, 0, sizeof(op));
+    op.payload = &op_payload;
+  };
   std::unique_ptr<Closure> c =
       MakeClosure([&](grpc_exec_ctx *exec_ctx, grpc_error *error) {
         if (!state.KeepRunning()) return;
-        memset(&op, 0, sizeof(op));
+        reset_op();
         op.on_complete = c.get();
         s.Op(&op);
       });
@@ -370,7 +383,12 @@ static void BM_TransportStreamSend(benchmark::State &state) {
   Fixture f(grpc::ChannelArguments(), true);
   Stream s(&f);
   s.Init(state);
-  grpc_transport_stream_op op;
+  grpc_transport_stream_op_batch op;
+  grpc_transport_stream_op_batch_payload op_payload;
+  auto reset_op = [&]() {
+    memset(&op, 0, sizeof(op));
+    op.payload = &op_payload;
+  };
   grpc_slice_buffer_stream send_stream;
   grpc_slice_buffer send_buffer;
   grpc_slice_buffer_init(&send_buffer);
@@ -397,20 +415,23 @@ static void BM_TransportStreamSend(benchmark::State &state) {
         s.chttp2_stream()->outgoing_window_delta = 1024 * 1024 * 1024;
         f.chttp2_transport()->outgoing_window = 1024 * 1024 * 1024;
         grpc_slice_buffer_stream_init(&send_stream, &send_buffer, 0);
-        memset(&op, 0, sizeof(op));
+        reset_op();
         op.on_complete = c.get();
-        op.send_message = &send_stream.base;
+        op.send_message = true;
+        op.payload->send_message.send_message = &send_stream.base;
         s.Op(&op);
       });
 
-  memset(&op, 0, sizeof(op));
-  op.send_initial_metadata = &b;
+  reset_op();
+  op.send_initial_metadata = true;
+  op.payload->send_initial_metadata.send_initial_metadata = &b;
   op.on_complete = c.get();
   s.Op(&op);
 
   f.FlushExecCtx();
-  memset(&op, 0, sizeof(op));
-  op.cancel_error = GRPC_ERROR_CANCELLED;
+  reset_op();
+  op.cancel_stream = true;
+  op.payload->cancel_stream.cancel_error = GRPC_ERROR_CANCELLED;
   s.Op(&op);
   s.DestroyThen(
       MakeOnceClosure([](grpc_exec_ctx *exec_ctx, grpc_error *error) {}));
@@ -483,10 +504,16 @@ static void BM_TransportStreamRecv(benchmark::State &state) {
   Fixture f(grpc::ChannelArguments(), true);
   Stream s(&f);
   s.Init(state);
-  grpc_transport_stream_op op;
+  grpc_transport_stream_op_batch_payload op_payload;
+  grpc_transport_stream_op_batch op;
   grpc_byte_stream *recv_stream;
   grpc_slice incoming_data = CreateIncomingDataSlice(state.range(0), 16384);
 
+  auto reset_op = [&]() {
+    memset(&op, 0, sizeof(op));
+    op.payload = &op_payload;
+  };
+
   grpc_metadata_batch b;
   grpc_metadata_batch_init(&b);
   grpc_metadata_batch b_recv;
@@ -518,10 +545,11 @@ static void BM_TransportStreamRecv(benchmark::State &state) {
         s.chttp2_stream()->incoming_window_delta = 1024 * 1024 * 1024;
         f.chttp2_transport()->incoming_window = 1024 * 1024 * 1024;
         received = 0;
-        memset(&op, 0, sizeof(op));
+        reset_op();
         op.on_complete = do_nothing.get();
-        op.recv_message = &recv_stream;
-        op.recv_message_ready = drain_start.get();
+        op.recv_message = true;
+        op.payload->recv_message.recv_message = &recv_stream;
+        op.payload->recv_message.recv_message_ready = drain_start.get();
         s.Op(&op);
         f.PushInput(grpc_slice_ref(incoming_data));
       });
@@ -552,9 +580,13 @@ static void BM_TransportStreamRecv(benchmark::State &state) {
     grpc_closure_run(exec_ctx, drain.get(), GRPC_ERROR_NONE);
   });
 
-  memset(&op, 0, sizeof(op));
-  op.send_initial_metadata = &b;
-  op.recv_initial_metadata = &b_recv;
+  reset_op();
+  op.send_initial_metadata = true;
+  op.payload->send_initial_metadata.send_initial_metadata = &b;
+  op.recv_initial_metadata = true;
+  op.payload->recv_initial_metadata.recv_initial_metadata = &b_recv;
+  op.payload->recv_initial_metadata.recv_initial_metadata_ready =
+      do_nothing.get();
   op.on_complete = c.get();
   s.Op(&op);
   f.PushInput(SLICE_FROM_BUFFER(
@@ -571,8 +603,9 @@ static void BM_TransportStreamRecv(benchmark::State &state) {
       "\x10\x14grpc-accept-encoding\x15identity,deflate,gzip"));
 
   f.FlushExecCtx();
-  memset(&op, 0, sizeof(op));
-  op.cancel_error = GRPC_ERROR_CANCELLED;
+  reset_op();
+  op.cancel_stream = true;
+  op.payload->cancel_stream.cancel_error = GRPC_ERROR_CANCELLED;
   s.Op(&op);
   s.DestroyThen(
       MakeOnceClosure([](grpc_exec_ctx *exec_ctx, grpc_error *error) {}));
diff --git a/test/cpp/qps/client_async.cc b/test/cpp/qps/client_async.cc
index 396d308e2a..29a79e7343 100644
--- a/test/cpp/qps/client_async.cc
+++ b/test/cpp/qps/client_async.cc
@@ -63,13 +63,13 @@ class ClientRpcContext {
   virtual ~ClientRpcContext() {}
   // next state, return false if done. Collect stats when appropriate
   virtual bool RunNextState(bool, HistogramEntry* entry) = 0;
-  virtual ClientRpcContext* StartNewClone() = 0;
+  virtual void StartNewClone(CompletionQueue* cq) = 0;
   static void* tag(ClientRpcContext* c) { return reinterpret_cast<void*>(c); }
   static ClientRpcContext* detag(void* t) {
     return reinterpret_cast<ClientRpcContext*>(t);
   }
 
-  virtual void Start(CompletionQueue* cq) = 0;
+  virtual void Start(CompletionQueue* cq, const ClientConfig& config) = 0;
 };
 
 template <class RequestType, class ResponseType>
@@ -94,22 +94,17 @@ class ClientRpcContextUnaryImpl : public ClientRpcContext {
         next_issue_(next_issue),
         start_req_(start_req) {}
   ~ClientRpcContextUnaryImpl() override {}
-  void Start(CompletionQueue* cq) override {
-    cq_ = cq;
-    if (!next_issue_) {  // ready to issue
-      RunNextState(true, nullptr);
-    } else {  // wait for the issue time
-      alarm_.reset(new Alarm(cq_, next_issue_(), ClientRpcContext::tag(this)));
-    }
+  void Start(CompletionQueue* cq, const ClientConfig& config) override {
+    StartInternal(cq);
   }
   bool RunNextState(bool ok, HistogramEntry* entry) override {
     switch (next_state_) {
       case State::READY:
         start_ = UsageTimer::Now();
         response_reader_ = start_req_(stub_, &context_, req_, cq_);
+        next_state_ = State::RESP_DONE;
         response_reader_->Finish(&response_, &status_,
                                  ClientRpcContext::tag(this));
-        next_state_ = State::RESP_DONE;
         return true;
       case State::RESP_DONE:
         if (status_.ok()) {
@@ -123,9 +118,10 @@ class ClientRpcContextUnaryImpl : public ClientRpcContext {
         return false;
     }
   }
-  ClientRpcContext* StartNewClone() override {
-    return new ClientRpcContextUnaryImpl(stub_, req_, next_issue_, start_req_,
-                                         callback_);
+  void StartNewClone(CompletionQueue* cq) override {
+    auto* clone = new ClientRpcContextUnaryImpl(stub_, req_, next_issue_,
+                                                start_req_, callback_);
+    clone->StartInternal(cq);
   }
 
  private:
@@ -147,6 +143,15 @@ class ClientRpcContextUnaryImpl : public ClientRpcContext {
   double start_;
   std::unique_ptr<grpc::ClientAsyncResponseReader<ResponseType>>
       response_reader_;
+
+  void StartInternal(CompletionQueue* cq) {
+    cq_ = cq;
+    if (!next_issue_) {  // ready to issue
+      RunNextState(true, nullptr);
+    } else {  // wait for the issue time
+      alarm_.reset(new Alarm(cq_, next_issue_(), ClientRpcContext::tag(this)));
+    }
+  }
 };
 
 typedef std::forward_list<ClientRpcContext*> context_list;
@@ -185,7 +190,7 @@ class AsyncClient : public ClientImpl<StubType, RequestType> {
         auto* cq = cli_cqs_[t].get();
         auto ctx =
             setup_ctx(channels_[ch].get_stub(), next_issuers_[t], request_);
-        ctx->Start(cq);
+        ctx->Start(cq, config);
       }
       t = (t + 1) % cli_cqs_.size();
     }
@@ -248,8 +253,7 @@ class AsyncClient : public ClientImpl<StubType, RequestType> {
         } else if (!ctx->RunNextState(ok, entry)) {
           // The RPC and callback are done, so clone the ctx
           // and kickstart the new one
-          auto clone = ctx->StartNewClone();
-          clone->Start(cli_cqs_[thread_idx].get());
+          ctx->StartNewClone(cli_cqs_[thread_idx].get());
           // delete the old version
           delete ctx;
         }
@@ -330,10 +334,8 @@ class ClientRpcContextStreamingImpl : public ClientRpcContext {
         next_issue_(next_issue),
         start_req_(start_req) {}
   ~ClientRpcContextStreamingImpl() override {}
-  void Start(CompletionQueue* cq) override {
-    cq_ = cq;
-    stream_ = start_req_(stub_, &context_, cq, ClientRpcContext::tag(this));
-    next_state_ = State::STREAM_IDLE;
+  void Start(CompletionQueue* cq, const ClientConfig& config) override {
+    StartInternal(cq, config.messages_per_stream());
   }
   bool RunNextState(bool ok, HistogramEntry* entry) override {
     while (true) {
@@ -346,9 +348,9 @@ class ClientRpcContextStreamingImpl : public ClientRpcContext {
           }
           break;  // loop around, don't return
         case State::WAIT:
+          next_state_ = State::READY_TO_WRITE;
           alarm_.reset(
               new Alarm(cq_, next_issue_(), ClientRpcContext::tag(this)));
-          next_state_ = State::READY_TO_WRITE;
           return true;
         case State::READY_TO_WRITE:
           if (!ok) {
@@ -369,17 +371,32 @@ class ClientRpcContextStreamingImpl : public ClientRpcContext {
         case State::READ_DONE:
           entry->set_value((UsageTimer::Now() - start_) * 1e9);
           callback_(status_, &response_);
+          if ((messages_per_stream_ != 0) &&
+              (++messages_issued_ >= messages_per_stream_)) {
+            next_state_ = State::WRITES_DONE_DONE;
+            stream_->WritesDone(ClientRpcContext::tag(this));
+            return true;
+          }
           next_state_ = State::STREAM_IDLE;
           break;  // loop around
+        case State::WRITES_DONE_DONE:
+          next_state_ = State::FINISH_DONE;
+          stream_->Finish(&status_, ClientRpcContext::tag(this));
+          return true;
+        case State::FINISH_DONE:
+          next_state_ = State::INVALID;
+          return false;
+          break;
         default:
           GPR_ASSERT(false);
           return false;
       }
     }
   }
-  ClientRpcContext* StartNewClone() override {
-    return new ClientRpcContextStreamingImpl(stub_, req_, next_issue_,
-                                             start_req_, callback_);
+  void StartNewClone(CompletionQueue* cq) override {
+    auto* clone = new ClientRpcContextStreamingImpl(stub_, req_, next_issue_,
+                                                    start_req_, callback_);
+    clone->StartInternal(cq, messages_per_stream_);
   }
 
  private:
@@ -395,7 +412,9 @@ class ClientRpcContextStreamingImpl : public ClientRpcContext {
     WAIT,
     READY_TO_WRITE,
     WRITE_DONE,
-    READ_DONE
+    READ_DONE,
+    WRITES_DONE_DONE,
+    FINISH_DONE
   };
   State next_state_;
   std::function<void(grpc::Status, ResponseType*)> callback_;
@@ -408,6 +427,18 @@ class ClientRpcContextStreamingImpl : public ClientRpcContext {
   double start_;
   std::unique_ptr<grpc::ClientAsyncReaderWriter<RequestType, ResponseType>>
       stream_;
+
+  // Allow a limit on number of messages in a stream
+  int messages_per_stream_;
+  int messages_issued_;
+
+  void StartInternal(CompletionQueue* cq, int messages_per_stream) {
+    cq_ = cq;
+    next_state_ = State::STREAM_IDLE;
+    stream_ = start_req_(stub_, &context_, cq, ClientRpcContext::tag(this));
+    messages_per_stream_ = messages_per_stream;
+    messages_issued_ = 0;
+  }
 };
 
 class AsyncStreamingClient final
@@ -459,13 +490,8 @@ class ClientRpcContextGenericStreamingImpl : public ClientRpcContext {
         next_issue_(next_issue),
         start_req_(start_req) {}
   ~ClientRpcContextGenericStreamingImpl() override {}
-  void Start(CompletionQueue* cq) override {
-    cq_ = cq;
-    const grpc::string kMethodName(
-        "/grpc.testing.BenchmarkService/StreamingCall");
-    stream_ = start_req_(stub_, &context_, kMethodName, cq,
-                         ClientRpcContext::tag(this));
-    next_state_ = State::STREAM_IDLE;
+  void Start(CompletionQueue* cq, const ClientConfig& config) override {
+    StartInternal(cq, config.messages_per_stream());
   }
   bool RunNextState(bool ok, HistogramEntry* entry) override {
     while (true) {
@@ -478,9 +504,9 @@ class ClientRpcContextGenericStreamingImpl : public ClientRpcContext {
           }
           break;  // loop around, don't return
         case State::WAIT:
+          next_state_ = State::READY_TO_WRITE;
           alarm_.reset(
               new Alarm(cq_, next_issue_(), ClientRpcContext::tag(this)));
-          next_state_ = State::READY_TO_WRITE;
           return true;
         case State::READY_TO_WRITE:
           if (!ok) {
@@ -501,17 +527,32 @@ class ClientRpcContextGenericStreamingImpl : public ClientRpcContext {
         case State::READ_DONE:
           entry->set_value((UsageTimer::Now() - start_) * 1e9);
           callback_(status_, &response_);
+          if ((messages_per_stream_ != 0) &&
+              (++messages_issued_ >= messages_per_stream_)) {
+            next_state_ = State::WRITES_DONE_DONE;
+            stream_->WritesDone(ClientRpcContext::tag(this));
+            return true;
+          }
           next_state_ = State::STREAM_IDLE;
           break;  // loop around
+        case State::WRITES_DONE_DONE:
+          next_state_ = State::FINISH_DONE;
+          stream_->Finish(&status_, ClientRpcContext::tag(this));
+          return true;
+        case State::FINISH_DONE:
+          next_state_ = State::INVALID;
+          return false;
+          break;
         default:
           GPR_ASSERT(false);
           return false;
       }
     }
   }
-  ClientRpcContext* StartNewClone() override {
-    return new ClientRpcContextGenericStreamingImpl(stub_, req_, next_issue_,
-                                                    start_req_, callback_);
+  void StartNewClone(CompletionQueue* cq) override {
+    auto* clone = new ClientRpcContextGenericStreamingImpl(
+        stub_, req_, next_issue_, start_req_, callback_);
+    clone->StartInternal(cq, messages_per_stream_);
   }
 
  private:
@@ -527,7 +568,9 @@ class ClientRpcContextGenericStreamingImpl : public ClientRpcContext {
     WAIT,
     READY_TO_WRITE,
     WRITE_DONE,
-    READ_DONE
+    READ_DONE,
+    WRITES_DONE_DONE,
+    FINISH_DONE
   };
   State next_state_;
   std::function<void(grpc::Status, ByteBuffer*)> callback_;
@@ -539,6 +582,21 @@ class ClientRpcContextGenericStreamingImpl : public ClientRpcContext {
   grpc::Status status_;
   double start_;
   std::unique_ptr<grpc::GenericClientAsyncReaderWriter> stream_;
+
+  // Allow a limit on number of messages in a stream
+  int messages_per_stream_;
+  int messages_issued_;
+
+  void StartInternal(CompletionQueue* cq, int messages_per_stream) {
+    cq_ = cq;
+    const grpc::string kMethodName(
+        "/grpc.testing.BenchmarkService/StreamingCall");
+    next_state_ = State::STREAM_IDLE;
+    stream_ = start_req_(stub_, &context_, kMethodName, cq,
+                         ClientRpcContext::tag(this));
+    messages_per_stream_ = messages_per_stream;
+    messages_issued_ = 0;
+  }
 };
 
 static std::unique_ptr<grpc::GenericStub> GenericStubCreator(
diff --git a/test/cpp/qps/client_sync.cc b/test/cpp/qps/client_sync.cc
index a944c45496..a020adde51 100644
--- a/test/cpp/qps/client_sync.cc
+++ b/test/cpp/qps/client_sync.cc
@@ -142,10 +142,13 @@ class SynchronousStreamingClient final : public SynchronousClient {
   SynchronousStreamingClient(const ClientConfig& config)
       : SynchronousClient(config),
         context_(num_threads_),
-        stream_(num_threads_) {
+        stream_(num_threads_),
+        messages_per_stream_(config.messages_per_stream()),
+        messages_issued_(num_threads_) {
     for (size_t thread_idx = 0; thread_idx < num_threads_; thread_idx++) {
       auto* stub = channels_[thread_idx % channels_.size()].get_stub();
       stream_[thread_idx] = stub->StreamingCall(&context_[thread_idx]);
+      messages_issued_[thread_idx] = 0;
     }
     StartThreads(num_threads_);
   }
@@ -173,11 +176,17 @@ class SynchronousStreamingClient final : public SynchronousClient {
         stream_[thread_idx]->Read(&responses_[thread_idx])) {
       entry->set_value((UsageTimer::Now() - start) * 1e9);
       // don't set the status since there isn't one yet
-      return true;
+      if ((messages_per_stream_ != 0) &&
+          (++messages_issued_[thread_idx] < messages_per_stream_)) {
+        return true;
+      } else {
+        // Fall through to the below resetting code after finish
+      }
     }
     stream_[thread_idx]->WritesDone();
     Status s = stream_[thread_idx]->Finish();
-    // don't set the value since the stream is failed and shouldn't be timed
+    // don't set the value since this is either a failure (shouldn't be timed)
+    // or a stream-end (already has been timed)
     entry->set_status(s.error_code());
     if (!s.ok()) {
       gpr_log(GPR_ERROR, "Stream %" PRIuPTR " received an error %s", thread_idx,
@@ -187,6 +196,7 @@ class SynchronousStreamingClient final : public SynchronousClient {
     context_[thread_idx].~ClientContext();
     new (&context_[thread_idx]) ClientContext();
     stream_[thread_idx] = stub->StreamingCall(&context_[thread_idx]);
+    messages_issued_[thread_idx] = 0;
     return true;
   }
 
@@ -197,6 +207,8 @@ class SynchronousStreamingClient final : public SynchronousClient {
   std::vector<
       std::unique_ptr<grpc::ClientReaderWriter<SimpleRequest, SimpleResponse>>>
       stream_;
+  const int messages_per_stream_;
+  std::vector<int> messages_issued_;
 };
 
 std::unique_ptr<Client> CreateSynchronousUnaryClient(
diff --git a/tools/run_tests/generated/tests.json b/tools/run_tests/generated/tests.json
index 7d2c51a7d4..b878bc1231 100644
--- a/tools/run_tests/generated/tests.json
+++ b/tools/run_tests/generated/tests.json
@@ -40776,6 +40776,56 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_unconstrained_1mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_generic_async_streaming_qps_unconstrained_1mps_secure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_unconstrained_10mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_generic_async_streaming_qps_unconstrained_10mps_secure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_1channel_1MBmsg_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 1048576, \"req_size\": 1048576}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 1048576, \"req_size\": 1048576}}, \"client_channels\": 1, \"async_client_threads\": 0, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -41105,6 +41155,56 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_sync_streaming_qps_unconstrained_1mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"server_type\": \"SYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"SYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 16, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": 1024, 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_sync_streaming_qps_unconstrained_1mps_secure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_sync_streaming_qps_unconstrained_10mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"server_type\": \"SYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"SYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 16, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": 1024, 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_sync_streaming_qps_unconstrained_10mps_secure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_ping_pong_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 1, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 1, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 1, \"async_client_threads\": 1, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -41155,6 +41255,56 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_qps_unconstrained_1mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_async_streaming_qps_unconstrained_1mps_secure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_qps_unconstrained_10mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_async_streaming_qps_unconstrained_10mps_secure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_ping_pong_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 1, \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 1, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 1, \"async_client_threads\": 1, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -41205,6 +41355,56 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_unconstrained_1mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_generic_async_streaming_qps_unconstrained_1mps_insecure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_unconstrained_10mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_generic_async_streaming_qps_unconstrained_10mps_insecure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_1channel_1MBmsg_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 1048576, \"req_size\": 1048576}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 1048576, \"req_size\": 1048576}}, \"client_channels\": 1, \"async_client_threads\": 0, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -41534,6 +41734,56 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_sync_streaming_qps_unconstrained_1mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"server_type\": \"SYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"SYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 16, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": 1024, 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_sync_streaming_qps_unconstrained_1mps_insecure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_sync_streaming_qps_unconstrained_10mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"server_type\": \"SYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"SYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 16, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": 1024, 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_sync_streaming_qps_unconstrained_10mps_insecure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_ping_pong_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 1, \"security_params\": null, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 1, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 1, \"async_client_threads\": 1, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -41584,6 +41834,56 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_qps_unconstrained_1mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_async_streaming_qps_unconstrained_1mps_insecure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_qps_unconstrained_10mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "tsan", 
+      "asan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_async_streaming_qps_unconstrained_10mps_insecure", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_ping_pong_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 1, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 1, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 1, \"async_client_threads\": 1, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -41658,6 +41958,80 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_unconstrained_1mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_generic_async_streaming_qps_unconstrained_1mps_secure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_unconstrained_10mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_generic_async_streaming_qps_unconstrained_10mps_secure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_1channel_1MBmsg_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 1048576, \"req_size\": 1048576}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 1048576, \"req_size\": 1048576}}, \"client_channels\": 1, \"async_client_threads\": 0, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -42143,6 +42517,80 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_sync_streaming_qps_unconstrained_1mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"server_type\": \"SYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"SYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": 64, 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_sync_streaming_qps_unconstrained_1mps_secure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_sync_streaming_qps_unconstrained_10mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"server_type\": \"SYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"SYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": 64, 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_sync_streaming_qps_unconstrained_10mps_secure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_ping_pong_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 1, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 1, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 1, \"async_client_threads\": 1, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -42217,6 +42665,80 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_qps_unconstrained_1mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_async_streaming_qps_unconstrained_1mps_secure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_qps_unconstrained_10mps_secure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": {\"use_test_ca\": true, \"server_host_override\": \"foo.test.google.fr\"}, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_async_streaming_qps_unconstrained_10mps_secure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_ping_pong_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 1, \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 1, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 1, \"async_client_threads\": 1, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -42291,6 +42813,80 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_unconstrained_1mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_generic_async_streaming_qps_unconstrained_1mps_insecure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_unconstrained_10mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_generic_async_streaming_qps_unconstrained_10mps_insecure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_generic_async_streaming_qps_1channel_1MBmsg_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 1048576, \"req_size\": 1048576}}, \"server_type\": \"ASYNC_GENERIC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"bytebuf_params\": {\"resp_size\": 1048576, \"req_size\": 1048576}}, \"client_channels\": 1, \"async_client_threads\": 0, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -42776,6 +43372,80 @@
   {
     "args": [
       "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_sync_streaming_qps_unconstrained_1mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"server_type\": \"SYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"SYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": 64, 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_sync_streaming_qps_unconstrained_1mps_insecure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_sync_streaming_qps_unconstrained_10mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"server_type\": \"SYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"SYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": 64, 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_sync_streaming_qps_unconstrained_10mps_insecure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
       "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_ping_pong_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 1, \"security_params\": null, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 1, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 1, \"async_client_threads\": 1, \"outstanding_rpcs_per_channel\": 1, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
     ], 
     "boringssl": true, 
@@ -42849,6 +43519,80 @@
   }, 
   {
     "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_qps_unconstrained_1mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 1, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_async_streaming_qps_unconstrained_1mps_insecure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
+      "--scenarios_json", 
+      "{\"scenarios\": [{\"name\": \"cpp_protobuf_async_streaming_qps_unconstrained_10mps_insecure\", \"warmup_seconds\": 0, \"benchmark_seconds\": 1, \"num_servers\": 1, \"server_config\": {\"async_server_threads\": 0, \"security_params\": null, \"server_type\": \"ASYNC_SERVER\"}, \"num_clients\": 0, \"client_config\": {\"client_type\": \"ASYNC_CLIENT\", \"security_params\": null, \"payload_config\": {\"simple_params\": {\"resp_size\": 0, \"req_size\": 0}}, \"client_channels\": 64, \"async_client_threads\": 0, \"messages_per_stream\": 10, \"outstanding_rpcs_per_channel\": 100, \"rpc_type\": \"STREAMING\", \"load_params\": {\"closed_loop\": {}}, \"histogram_params\": {\"max_possible\": 60000000000.0, \"resolution\": 0.01}}}]}"
+    ], 
+    "boringssl": true, 
+    "ci_platforms": [
+      "linux"
+    ], 
+    "cpu_cost": "capacity", 
+    "defaults": "boringssl", 
+    "exclude_configs": [
+      "asan-noleaks", 
+      "asan-trace-cmp", 
+      "basicprof", 
+      "counters", 
+      "dbg", 
+      "gcov", 
+      "helgrind", 
+      "lto", 
+      "memcheck", 
+      "msan", 
+      "mutrace", 
+      "opt", 
+      "stapprof", 
+      "ubsan"
+    ], 
+    "excluded_poll_engines": [], 
+    "flaky": false, 
+    "language": "c++", 
+    "name": "json_run_localhost", 
+    "platforms": [
+      "linux"
+    ], 
+    "shortname": "json_run_localhost:cpp_protobuf_async_streaming_qps_unconstrained_10mps_insecure_low_thread_count", 
+    "timeout_seconds": 360
+  }, 
+  {
+    "args": [
       "test/core/end2end/fuzzers/api_fuzzer_corpus/00.bin"
     ], 
     "ci_platforms": [
diff --git a/tools/run_tests/performance/scenario_config.py b/tools/run_tests/performance/scenario_config.py
index af510fe049..dca3fba099 100644
--- a/tools/run_tests/performance/scenario_config.py
+++ b/tools/run_tests/performance/scenario_config.py
@@ -112,6 +112,7 @@ def _ping_pong_scenario(name, rpc_type,
                         channels=None,
                         outstanding=None,
                         resource_quota_size=None,
+                        messages_per_stream=None,
                         excluded_poll_engines=[]):
   """Creates a basic ping pong scenario."""
   scenario = {
@@ -165,6 +166,8 @@ def _ping_pong_scenario(name, rpc_type,
     scenario['client_config']['client_channels'] = 1
     scenario['client_config']['async_client_threads'] = 1
 
+  if messages_per_stream:
+    scenario['client_config']['messages_per_stream'] = messages_per_stream
   if client_language:
     # the CLIENT_LANGUAGE field is recognized by run_performance_tests.py
     scenario['CLIENT_LANGUAGE'] = client_language
@@ -214,6 +217,26 @@ class CXXLanguage:
           secure=secure,
           categories=smoketest_categories+[SCALABLE])
 
+      for mps in geometric_progression(1, 20, 10):
+        yield _ping_pong_scenario(
+            'cpp_generic_async_streaming_qps_unconstrained_%smps_%s' % (mps, secstr),
+            rpc_type='STREAMING',
+            client_type='ASYNC_CLIENT',
+            server_type='ASYNC_GENERIC_SERVER',
+            unconstrained_client='async', use_generic_payload=True,
+            secure=secure, messages_per_stream=mps,
+            categories=smoketest_categories+[SCALABLE])
+
+      for mps in geometric_progression(1, 200, math.sqrt(10)):
+        yield _ping_pong_scenario(
+            'cpp_generic_async_streaming_qps_unconstrained_%smps_%s' % (mps, secstr),
+            rpc_type='STREAMING',
+            client_type='ASYNC_CLIENT',
+            server_type='ASYNC_GENERIC_SERVER',
+            unconstrained_client='async', use_generic_payload=True,
+            secure=secure, messages_per_stream=mps,
+            categories=[SWEEP])
+
       yield _ping_pong_scenario(
           'cpp_generic_async_streaming_qps_1channel_1MBmsg_%s' % secstr,
           rpc_type='STREAMING',
@@ -331,6 +354,27 @@ class CXXLanguage:
           #     categories=smoketest_categories+[SCALABLE],
           #     resource_quota_size=500*1024)
 
+          if rpc_type == 'streaming':
+            for mps in geometric_progression(1, 20, 10):
+              yield _ping_pong_scenario(
+                  'cpp_protobuf_%s_%s_qps_unconstrained_%smps_%s' % (synchronicity, rpc_type, mps, secstr),
+                  rpc_type=rpc_type.upper(),
+                  client_type='%s_CLIENT' % synchronicity.upper(),
+                  server_type='%s_SERVER' % synchronicity.upper(),
+                  unconstrained_client=synchronicity,
+                  secure=secure, messages_per_stream=mps,
+                  categories=smoketest_categories+[SCALABLE])
+
+            for mps in geometric_progression(1, 200, math.sqrt(10)):
+              yield _ping_pong_scenario(
+                  'cpp_protobuf_%s_%s_qps_unconstrained_%smps_%s' % (synchronicity, rpc_type, mps, secstr),
+                  rpc_type=rpc_type.upper(),
+                  client_type='%s_CLIENT' % synchronicity.upper(),
+                  server_type='%s_SERVER' % synchronicity.upper(),
+                  unconstrained_client=synchronicity,
+                  secure=secure, messages_per_stream=mps,
+                  categories=[SWEEP])
+
           for channels in geometric_progression(1, 20000, math.sqrt(10)):
             for outstanding in geometric_progression(1, 200000, math.sqrt(10)):
                 if synchronicity == 'sync' and outstanding > 1200: continue