LXR linux/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
  32static int loops = LOOPS_DEFAULT;
  33
  34static const struct option options[] = {
  35        OPT_INTEGER('l', "loop", &loops,
  36                    "Specify number of loops"),
  37        OPT_END()
  38};
  39
  40static const char * const bench_sched_pipe_usage[] = {
  41        "perf bench sched pipe <options>",
  42        NULL
  43};
  44
  45int bench_sched_pipe(int argc, const char **argv,
  46                     const char *prefix __maybe_unused)
  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 __maybe_unused ret, wait_stat;
  59        pid_t pid, retpid __maybe_unused;
  60
  61        argc = parse_options(argc, argv, options,
  62                             bench_sched_pipe_usage, 0);
  63
  64        BUG_ON(pipe(pipe_1));
  65        BUG_ON(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}
 128