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 __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