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}
125