tools/testing/selftests/timers/mqueue-lat.c

   1 /* Measure mqueue timeout latency
   2  *              by: john stultz (john.stultz@linaro.org)
   3  *              (C) Copyright Linaro 2013
   4  *
   5  *              Inspired with permission from example test by:
   6  *                      Romain Francoise <romain@orebokech.com>
   7  *              Licensed under the GPLv2
   8  *
   9  *  To build:
  10  *      $ gcc mqueue-lat.c -o mqueue-lat -lrt
  11  *
  12  *   This program is free software: you can redistribute it and/or modify
  13  *   it under the terms of the GNU General Public License as published by
  14  *   the Free Software Foundation, either version 2 of the License, or
  15  *   (at your option) any later version.
  16  *
  17  *   This program is distributed in the hope that it will be useful,
  18  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  *   GNU General Public License for more details.
  21  */
  22
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <time.h>
  26 #include <sys/time.h>
  27 #include <sys/timex.h>
  28 #include <string.h>
  29 #include <signal.h>
  30 #include <errno.h>
  31 #include <mqueue.h>
  32 #ifdef KTEST
  33 #include "../kselftest.h"
  34 #else
  35 static inline int ksft_exit_pass(void)
  36 {
  37         exit(0);
  38 }
  39 static inline int ksft_exit_fail(void)
  40 {
  41         exit(1);
  42 }
  43 #endif
  44
  45 #define NSEC_PER_SEC 1000000000ULL
  46
  47 #define TARGET_TIMEOUT          100000000       /* 100ms in nanoseconds */
  48 #define UNRESONABLE_LATENCY     40000000        /* 40ms in nanosecs */
  49
  50
  51 long long timespec_sub(struct timespec a, struct timespec b)
  52 {
  53         long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec;
  54
  55         ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec;
  56         return ret;
  57 }
  58
  59 struct timespec timespec_add(struct timespec ts, unsigned long long ns)
  60 {
  61         ts.tv_nsec += ns;
  62         while (ts.tv_nsec >= NSEC_PER_SEC) {
  63                 ts.tv_nsec -= NSEC_PER_SEC;
  64                 ts.tv_sec++;
  65         }
  66         return ts;
  67 }
  68
  69 int mqueue_lat_test(void)
  70 {
  71
  72         mqd_t q;
  73         struct mq_attr attr;
  74         struct timespec start, end, now, target;
  75         int i, count, ret;
  76
  77         q = mq_open("/foo", O_CREAT | O_RDONLY, 0666, NULL);
  78         if (q < 0) {
  79                 perror("mq_open");
  80                 return -1;
  81         }
  82         mq_getattr(q, &attr);
  83
  84
  85         count = 100;
  86         clock_gettime(CLOCK_MONOTONIC, &start);
  87
  88         for (i = 0; i < count; i++) {
  89                 char buf[attr.mq_msgsize];
  90
  91                 clock_gettime(CLOCK_REALTIME, &now);
  92                 target = now;
  93                 target = timespec_add(now, TARGET_TIMEOUT); /* 100ms */
  94
  95                 ret = mq_timedreceive(q, buf, sizeof(buf), NULL, &target);
  96                 if (ret < 0 && errno != ETIMEDOUT) {
  97                         perror("mq_timedreceive");
  98                         return -1;
  99                 }
 100         }
 101         clock_gettime(CLOCK_MONOTONIC, &end);
 102
 103         mq_close(q);
 104
 105         if ((timespec_sub(start, end)/count) > TARGET_TIMEOUT + UNRESONABLE_LATENCY)
 106                 return -1;
 107
 108         return 0;
 109 }
 110
 111 int main(int argc, char **argv)
 112 {
 113         int ret;
 114
 115         printf("Mqueue latency :                          ");
 116
 117         ret = mqueue_lat_test();
 118         if (ret < 0) {
 119                 printf("[FAILED]\n");
 120                 return ksft_exit_fail();
 121         }
 122         printf("[OK]\n");
 123         return ksft_exit_pass();
 124 }