tools/perf/bench/sched-pipe.c

   1 /*
   2  *
   3  * sched-pipe.c
   4  *
   5  * pipe: Benchmark for pipe()
   6  *
   7  * Based on pipe-test-1m.c by Ingo Molnar <mingo@redhat.com>
   8  *  http://people.redhat.com/mingo/cfs-scheduler/tools/pipe-test-1m.c
   9  * Ported to perf by Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
  10  *
  11  */
  12
  13 #include "../perf.h"
  14 #include "../util/util.h"
  15 #include "../util/parse-options.h"
  16 #include "../builtin.h"
  17 #include "bench.h"
  18
  19 #include <unistd.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <signal.h>
  23 #include <sys/wait.h>
  24 #include <linux/unistd.h>
  25 #include <string.h>
  26 #include <errno.h>
  27 #include <assert.h>
  28 #include <sys/time.h>
  29 #include <sys/types.h>
  30
  31 #define LOOPS_DEFAULT 1000000
  32 static int loops = LOOPS_DEFAULT;
  33
  34 static const struct option options[] = {
  35         OPT_INTEGER('l', "loop", &loops,
  36                     "Specify number of loops"),
  37         OPT_END()
  38 };
  39
  40 static const char * const bench_sched_pipe_usage[] = {
  41         "perf bench sched pipe <options>",
  42         NULL
  43 };
  44
  45 int bench_sched_pipe(int argc, const char **argv,
  46                      const char *prefix __used)
  47 {
  48         int pipe_1[2], pipe_2[2];
  49         int m = 0, i;
  50         struct timeval start, stop, diff;
  51         unsigned long long result_usec = 0;
  52
  53         /*
  54          * why does "ret" exist?
  55          * discarding returned value of read(), write()
  56          * causes error in building environment for perf
  57          */
  58         int __used ret, wait_stat;
  59         pid_t pid, retpid;
  60
  61         argc = parse_options(argc, argv, options,
  62                              bench_sched_pipe_usage, 0);
  63
  64         assert(!pipe(pipe_1));
  65         assert(!pipe(pipe_2));
  66
  67         pid = fork();
  68         assert(pid >= 0);
  69
  70         gettimeofday(&start, NULL);
  71
  72         if (!pid) {
  73                 for (i = 0; i < loops; i++) {
  74                         ret = read(pipe_1[0], &m, sizeof(int));
  75                         ret = write(pipe_2[1], &m, sizeof(int));
  76                 }
  77         } else {
  78                 for (i = 0; i < loops; i++) {
  79                         ret = write(pipe_1[1], &m, sizeof(int));
  80                         ret = read(pipe_2[0], &m, sizeof(int));
  81                 }
  82         }
  83
  84         gettimeofday(&stop, NULL);
  85         timersub(&stop, &start, &diff);
  86
  87         if (pid) {
  88                 retpid = waitpid(pid, &wait_stat, 0);
  89                 assert((retpid == pid) && WIFEXITED(wait_stat));
  90         } else {
  91                 exit(0);
  92         }
  93
  94         switch (bench_format) {
  95         case BENCH_FORMAT_DEFAULT:
  96                 printf("# Executed %d pipe operations between two tasks\n\n",
  97                         loops);
  98
  99                 result_usec = diff.tv_sec * 1000000;
 100                 result_usec += diff.tv_usec;
 101
 102                 printf(" %14s: %lu.%03lu [sec]\n\n", "Total time",
 103                        diff.tv_sec,
 104                        (unsigned long) (diff.tv_usec/1000));
 105
 106                 printf(" %14lf usecs/op\n",
 107                        (double)result_usec / (double)loops);
 108                 printf(" %14d ops/sec\n",
 109                        (int)((double)loops /
 110                              ((double)result_usec / (double)1000000)));
 111                 break;
 112
 113         case BENCH_FORMAT_SIMPLE:
 114                 printf("%lu.%03lu\n",
 115                        diff.tv_sec,
 116                        (unsigned long) (diff.tv_usec / 1000));
 117                 break;
 118
 119         default:
 120                 /* reaching here is something disaster */
 121                 fprintf(stderr, "Unknown format:%d\n", bench_format);
 122                 exit(1);
 123                 break;
 124         }
 125
 126         return 0;
 127 }