benchmark.c

   1 #define _POSIX_C_SOURCE 200809L
   2 #include <time.h>
   3 #include <unistd.h>
   4 #include <sys/types.h>
   5 #include <signal.h>
   6 #include <sys/wait.h>
   7 #include <assert.h>
   8 #include <ctype.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <stdio.h>
  12
  13 static int run(char** argv) {
  14         pid_t child, ret;
  15         int stat_loc;
  16         if((child = fork()) == 0) {
  17                 execvp(argv[0], argv);
  18                 perror("execvp");
  19                 _exit(1);
  20         } else {
  21                 ret = waitpid(child, &stat_loc, 0);
  22                 assert(ret == child);
  23                 return WIFEXITED(stat_loc) ? 0 : WTERMSIG(stat_loc);
  24         }
  25         return 0;
  26 }
  27
  28 static void usage() {
  29         printf(
  30                 "benchmark N COMMAND [ARGS...]\n"
  31                 "runs COMMAND (with ARGS) N times and prints timings.\n"
  32         );
  33         exit(1);
  34 }
  35
  36 #define NANOSECS 1000000000LL
  37
  38 long long timespectoll(struct timespec *ts) {
  39         return ts->tv_sec*NANOSECS + ts->tv_nsec;
  40 }
  41
  42 char *fmt(long long n) {
  43         char buf[256];
  44         sprintf(buf, "%lld.%04lld", n/NANOSECS, (n%NANOSECS)/(NANOSECS/1000));
  45         return strdup(buf);
  46 }
  47
  48 int main(int argc, char** argv) {
  49         if(argc < 3 || !isdigit(argv[1][0])) usage();
  50         int i, n = atoi(argv[1]);
  51         argv++;
  52         argv++;
  53         long long *results = calloc(n, sizeof *results);
  54         for (i=0; i<n; ++i) {
  55                 struct timespec b_start, b_end;
  56                 assert(0 == clock_gettime(CLOCK_MONOTONIC, &b_start));
  57                 run(argv);
  58                 assert(0 == clock_gettime(CLOCK_MONOTONIC, &b_end));
  59                 results[i] = timespectoll(&b_end) - timespectoll(&b_start);
  60         }
  61         long long best = 0x7fffffffffffffffLL, sum = 0;
  62         for (i=0; i<n; ++i) {
  63                 if(results[i] < best) best = results[i];
  64                 sum += results[i] ;
  65         }
  66         printf("called %d times, best result: %ss, avg: %ss, total: %ss\n",
  67                 n, fmt(best), fmt(sum/(long long)n), fmt(sum));
  68         return 0;
  69 }
  70