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
 35static inline int ksft_exit_pass(void)
 36{
 37	exit(0);
 38}
 39static 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
 51long 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
 59struct 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
 69int 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
111int 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}