Prefix inaccurate costs with "~" in VirtualScheduler verbose log.

Fix some inaccurate estimates exposed by this approach:
- propagate the inaccuracy flag when merging device stats;
- estimate Const as no-op;
- estimate RandomUniform, Relu and Softmax as element-wise;
- consider estimates accurate for known element-wise ops in op_level_cost_estimator.

PiperOrigin-RevId: 177643976

1 files changed, 24 insertions, 8 deletions

diff --git a/tensorflow/core/grappler/costs/virtual_scheduler.cc b/tensorflow/core/grappler/costs/virtual_scheduler.cc
index 6640de668d..1554aeb3c0 100644
--- a/tensorflow/core/grappler/costs/virtual_scheduler.cc
+++ b/tensorflow/core/grappler/costs/virtual_scheduler.cc
@@ -43,6 +43,9 @@ Costs CombineCosts(const Costs& left, const Costs& right) {
 
   Costs result = left;
   result.execution_time += right.execution_time;
+  if (right.inaccurate) {
+    result.inaccurate = true;
+  }
   if (right.max_memory != kMemoryUnknown) {
     result.max_memory += right.max_memory;
   }
@@ -538,7 +541,8 @@ bool VirtualScheduler::MarkCurrNodeExecuted(const Costs& node_costs) {
   string node_description = GetOpDescription(op_context.op_info);
   op_counts_[node_description] += 1;
   op_costs_[node_description] =
-      node_costs.execution_time.asMicroSeconds().count();
+      std::make_pair(node_costs.execution_time.asMicroSeconds().count(),
+                     !node_costs.inaccurate);
 
   auto& op_cost = FindOrCreateZero(op_name, &op_to_cost_);
   op_cost = CombineCosts(op_cost, node_costs);
@@ -647,8 +651,10 @@ Costs VirtualScheduler::Summary() const {
   for (const auto& op_cost_pair : op_to_cost_) {
     const auto& op = op_cost_pair.first;
     const auto& cost = op_cost_pair.second.execution_time.count();
+    const bool is_op_cost_accurate = !op_cost_pair.second.inaccurate;
     if (cost) {  // Skip printing out zero-cost ops.
-      VLOG(1) << " + " << op << " : " << cost;
+      VLOG(1) << " + " << op << " : " << (is_op_cost_accurate ? "" : "~")
+              << cost;
     }
   }
 
@@ -699,10 +705,16 @@ Costs VirtualScheduler::Summary() const {
           CalculateOutputSize(node_map_.at(node).output_properties, port);
     }
     Costs::NanoSeconds total_compute_time_ns;
+    bool is_total_cost_accurate = true;
     for (const auto& op_cost_pair : state.op_to_cost) {
       const auto& op = op_cost_pair.first;
       const auto& cost = op_cost_pair.second.execution_time.count();
       total_compute_time_ns += op_cost_pair.second.execution_time;
+      const bool is_op_cost_accurate = !op_cost_pair.second.inaccurate;
+      if (!is_op_cost_accurate) {
+        is_total_cost_accurate = false;
+      }
+
       int64 op_mem_usage = 0;
       auto it = op_to_memory.find(op);
       if (it != op_to_memory.end()) {
@@ -714,9 +726,9 @@ Costs VirtualScheduler::Summary() const {
                                : 0.0;
       if (cost || mem_usage_percent > 1.0) {
         // Print out only non-zero cost ops or ops with > 1% memory usage.
-        VLOG(1) << " + " << op << " : " << cost << " ("
-                << strings::HumanReadableNumBytes(op_mem_usage) << " ["
-                << mem_usage_percent << "%] "
+        VLOG(1) << " + " << op << " : " << (is_op_cost_accurate ? "" : "~")
+                << cost << " (" << strings::HumanReadableNumBytes(op_mem_usage)
+                << " [" << mem_usage_percent << "%] "
                 << (persisent_ops.count(op) > 0 ? ": persistent op)" : ")");
       }
     }
@@ -725,8 +737,9 @@ Costs VirtualScheduler::Summary() const {
     if (wall_time_ns.count() > 0) {
       utilization = total_compute_time_ns.count() * 100 / wall_time_ns.count();
     }
-    VLOG(1) << "Device = " << name
-            << ", total_compute_time_ns = " << total_compute_time_ns.count()
+    VLOG(1) << "Device = " << name << ", total_compute_time_ns = "
+            << (is_total_cost_accurate ? "" : "~")
+            << total_compute_time_ns.count()
             << ", utilization = " << utilization << "%";
 
     if (critical_path_costs.execution_time <= state.GetCurrTime()) {
@@ -738,8 +751,11 @@ Costs VirtualScheduler::Summary() const {
     // Also log the op description and their corresponding counts.
     VLOG(2) << "Node description, counts, cost:";
     for (const auto& item : op_counts_) {
+      int cost;
+      bool is_cost_accurate;
+      std::tie(cost, is_cost_accurate) = op_costs_.at(item.first);
       VLOG(2) << "Node: " << item.first << ", Count: " << item.second
-              << ", Individual Cost: " << op_costs_.at(item.first);
+              << ", Individual Cost: " << (is_cost_accurate ? "" : "~") << cost;
     }
   }