Root/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 __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}
128

Archive Download this file



interactive