/* $NetBSD: latency2.c,v 1.4 2009/01/28 21:52:49 ad Exp $ */
/*-
* Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Two threads are involved in the test. Every 100ms the first thread
* wakes the second. The time taken for the wakeup to arrive is
* measured. Ctrl-C ends the test.
*/
#include <sys/mman.h>
#include <sys/resource.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sched.h>
#include <limits.h>
#include <signal.h>
#include <err.h>
#include <lwp.h>
pthread_barrier_t barrier;
struct timespec start;
int done;
long max = 0;
long min = LONG_MAX;
lwpid_t lid;
long sum;
long samples;
static void
sigint(int junk)
{
done = 1;
}
static void *
reader(void *cookie)
{
struct timespec end;
long val;
lid = _lwp_self();
for (;;) {
(void)pthread_barrier_wait(&barrier);
while (_lwp_park(NULL, 0, &lid, NULL) != 0) {
/* nothing */
}
clock_gettime(CLOCK_MONOTONIC, &end);
timespecsub(&end, &start, &end);
val = (long)end.tv_sec * 1000000000 + (long)end.tv_nsec;
printf("%ld\n", val);
if (val > max)
max = val;
if (val < min)
min = val;
sum += val;
samples++;
}
}
int
main(int argc, char *argv[])
{
static struct timespec delay = { 0, 100000000 }; /* 100ms */
struct sched_param sp;
pthread_t pt;
cpuset_t *cs;
int cpuid;
(void)setvbuf(stdout, NULL, _IOLBF, BUFSIZ);
if (geteuid() != 0) {
errx(1, "run me as root");
}
pthread_barrier_init(&barrier, NULL, 2);
if (pthread_create(&pt, NULL, reader, NULL)) {
errx(1, "pthread_create failed");
}
if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
err(1, "mlockall");
}
if (signal(SIGINT, sigint)) {
err(1, "siginal");
}
if (argc < 2) {
cs = cpuset_create();
if (cs == NULL) {
err(1, "cpuset_create");
}
cpuset_zero(cs);
cpuid = pthread_curcpu_np();
cpuset_set(cpuid, cs);
if (_sched_setaffinity(0, 0, cpuset_size(cs), cs) < 0) {
err(1, "_sched_setaffinity");
}
cpuset_destroy(cs);
}
sp.sched_priority = sched_get_priority_max(SCHED_FIFO) - 2;
if (pthread_setschedparam(pthread_self(), SCHED_FIFO, &sp)) {
errx(1, "pthread_setschedparam");
}
sp.sched_priority = sched_get_priority_max(SCHED_FIFO) - 1;
if (pthread_setschedparam(pt, SCHED_FIFO, &sp)) {
errx(1, "pthread_setschedparam");
}
do {
(void)pthread_barrier_wait(&barrier);
while (nanosleep(&delay, NULL) != 0) {
/* nothing */
}
clock_gettime(CLOCK_MONOTONIC, &start);
if (_lwp_unpark(lid, &lid) != 0) {
err(1, "_lwp_unpark");
}
} while (!done);
printf("\nmin=%ldns, max=%ldns, mean=%ldns\n", min, max, sum / samples);
return 0;
}
