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