1 files changed, 150 insertions, 0 deletions
diff --git a/test/core/gpr/cpu_test.cc b/test/core/gpr/cpu_test.cc
new file mode 100644
index 0000000000..1052d40b42
--- /dev/null
+++ b/test/core/gpr/cpu_test.cc
@@ -0,0 +1,150 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+/* Test gpr per-cpu support:
+   gpr_cpu_num_cores()
+   gpr_cpu_current_cpu()
+*/
+
+#include <grpc/support/cpu.h>
+
+#include <stdio.h>
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/sync.h>
+#include <grpc/support/time.h>
+
+#include "src/core/lib/gprpp/thd.h"
+#include "test/core/util/test_config.h"
+
+/* Test structure is essentially:
+   1) Figure out how many cores are present on the test system
+   2) Create 3 times that many threads
+   3) Have each thread do some amount of work (basically want to
+      gaurantee that all threads are running at once, and enough of them
+      to run on all cores).
+   4) Each thread checks what core it is running on, and marks that core
+      as "used" in the test.
+   5) Count number of "used" cores.
+
+   The test will fail if:
+   1) gpr_cpu_num_cores() == 0
+   2) Any result from gpr_cpu_current_cpu() >= gpr_cpu_num_cores()
+   3) Ideally, we would fail if not all cores were seen as used. Unfortunately,
+      this is only probabilistically true, and depends on the OS, it's
+      scheduler, etc. So we just print out an indication of how many were seen;
+      hopefully developers can use this to sanity check their system.
+*/
+
+/* Status shared across threads */
+struct cpu_test {
+  gpr_mu mu;
+  int nthreads;
+  uint32_t ncores;
+  int is_done;
+  gpr_cv done_cv;
+  int* used;  /* is this core used? */
+  unsigned r; /* random number */
+};
+
+static void worker_thread(void* arg) {
+  struct cpu_test* ct = static_cast<struct cpu_test*>(arg);
+  uint32_t cpu;
+  unsigned r = 12345678;
+  unsigned i, j;
+  /* Avoid repetitive division calculations */
+  int64_t max_i = 1000 / grpc_test_slowdown_factor();
+  int64_t max_j = 1000 / grpc_test_slowdown_factor();
+  for (i = 0; i < max_i; i++) {
+    /* run for a bit - just calculate something random. */
+    for (j = 0; j < max_j; j++) {
+      r = (r * 17) & ((r - i) | (r * i));
+    }
+    cpu = gpr_cpu_current_cpu();
+    GPR_ASSERT(cpu < ct->ncores);
+    gpr_mu_lock(&ct->mu);
+    ct->used[cpu] = 1;
+    for (j = 0; j < ct->ncores; j++) {
+      if (!ct->used[j]) break;
+    }
+    gpr_mu_unlock(&ct->mu);
+    if (j == ct->ncores) {
+      break; /* all cpus have been used - no further use in running this test */
+    }
+  }
+  gpr_mu_lock(&ct->mu);
+  ct->r = r; /* make it look like we care about r's value... */
+  ct->nthreads--;
+  if (ct->nthreads == 0) {
+    ct->is_done = 1;
+    gpr_cv_signal(&ct->done_cv);
+  }
+  gpr_mu_unlock(&ct->mu);
+}
+
+static void cpu_test(void) {
+  uint32_t i;
+  int cores_seen = 0;
+  struct cpu_test ct;
+  ct.ncores = gpr_cpu_num_cores();
+  GPR_ASSERT(ct.ncores > 0);
+  ct.nthreads = static_cast<int>(ct.ncores) * 3;
+  ct.used = static_cast<int*>(gpr_malloc(ct.ncores * sizeof(int)));
+  memset(ct.used, 0, ct.ncores * sizeof(int));
+  gpr_mu_init(&ct.mu);
+  gpr_cv_init(&ct.done_cv);
+  ct.is_done = 0;
+
+  uint32_t nthreads = ct.ncores * 3;
+  grpc_core::Thread* thd =
+      static_cast<grpc_core::Thread*>(gpr_malloc(sizeof(*thd) * nthreads));
+
+  for (i = 0; i < nthreads; i++) {
+    thd[i] = grpc_core::Thread("grpc_cpu_test", &worker_thread, &ct);
+    thd[i].Start();
+  }
+  gpr_mu_lock(&ct.mu);
+  while (!ct.is_done) {
+    gpr_cv_wait(&ct.done_cv, &ct.mu, gpr_inf_future(GPR_CLOCK_MONOTONIC));
+  }
+  gpr_mu_unlock(&ct.mu);
+  for (i = 0; i < nthreads; i++) {
+    thd[i].Join();
+  }
+  gpr_free(thd);
+  fprintf(stderr, "Saw cores [");
+  fflush(stderr);
+  for (i = 0; i < ct.ncores; i++) {
+    if (ct.used[i]) {
+      fprintf(stderr, "%d,", i);
+      fflush(stderr);
+      cores_seen++;
+    }
+  }
+  fprintf(stderr, "] (%d/%d)\n", cores_seen, ct.ncores);
+  fflush(stderr);
+  gpr_free(ct.used);
+}
+
+int main(int argc, char* argv[]) {
+  grpc_test_init(argc, argv);
+  cpu_test();
+  return 0;
+}