Merge remote branch 'cros/upstream' into tempbranch

client/tests/tracing_microbenchmark/src/getuid_microbench.c

+#define _GNU_SOURCE
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <time.h>
+
+void ts_subtract(struct timespec *result,
+                 const struct timespec *time1, const struct timespec *time2) {
+  *result = *time1;
+  result->tv_sec -= time2->tv_sec ;
+  if (result->tv_nsec < time2->tv_nsec) {
+    /* borrow a second */
+    result->tv_nsec += 1000000000L;
+    result->tv_sec--;
+  }
+  result->tv_nsec -= time2->tv_nsec;
+}
+
+void usage(const char *cmd) {
+    fprintf(stderr, "usage: %s <iterations>\n", cmd);
+}
+
+int main (int argc, char *argv[]) {
+  struct timespec start_time, end_time, elapsed_time;
+  uid_t uid;
+  long iterations, i;
+  double per_call;
+
+  if (argc != 2) {
+    usage(argv[0]);
+    return 1;
+  }
+
+  iterations = atol(argv[1]);
+  if (iterations < 0) {
+    usage(argv[0]);
+    return 1;
+  }
+
+  if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start_time)) {
+    perror("clock_gettime");
+    return errno;
+  }
+
+  for (i = iterations; i; i--)
+    uid = syscall(SYS_getuid);
+
+  if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end_time)) {
+    perror("clock_gettime");
+    return errno;
+  }
+
+  ts_subtract(&elapsed_time, &end_time, &start_time);
+  per_call = (elapsed_time.tv_sec * 1000000000.0L + elapsed_time.tv_nsec) /
+      (double)iterations;
+  printf("%ld calls in %ld.%09ld s (%lf ns/call)\n", iterations,
+         elapsed_time.tv_sec, elapsed_time.tv_nsec, per_call);
+
+  return 0;
+}