regress/sys/kern/latency2/latency2.c

   1 /*      $NetBSD: latency2.c,v 1.3 2008/06/16 01:41:21 rmind Exp $       */
   2
   3 /*-
   4  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  26  * POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /*
  30  * Two threads are involved in the test.  Every 100ms the first thread
  31  * wakes the second.  The time taken for the wakeup to arrive is
  32  * measured.  Ctrl-C ends the test.
  33  */
  34
  35 #include <sys/mman.h>
  36 #include <sys/resource.h>
  37
  38 #include <pthread.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <unistd.h>
  42 #include <sched.h>
  43 #include <limits.h>
  44 #include <signal.h>
  45 #include <err.h>
  46 #include <lwp.h>
  47
  48 pthread_barrier_t       barrier;
  49 struct timespec         start;
  50 int                     done;
  51 long                    max = 0;
  52 long                    min = LONG_MAX;
  53 lwpid_t                 lid;
  54 long                    sum;
  55 long                    samples;
  56
  57 static void
  58 sigint(int junk)
  59 {
  60
  61         done = 1;
  62 }
  63
  64 static void *
  65 reader(void *cookie)
  66 {
  67         struct timespec end;
  68         long val;
  69
  70         lid = _lwp_self();
  71
  72         for (;;) {
  73                 (void)pthread_barrier_wait(&barrier);
  74                 while (_lwp_park(NULL, 0, &lid, NULL) != 0) {
  75                         /* nothing */
  76                 }
  77                 clock_gettime(CLOCK_MONOTONIC, &end);
  78                 timespecsub(&end, &start, &end);
  79                 val = (long)end.tv_sec * 1000000000 + (long)end.tv_nsec;
  80                 printf("%ld\n", val);
  81                 if (val > max)
  82                         max = val;
  83                 if (val < min)
  84                         min = val;
  85                 sum += val;
  86                 samples++;
  87         }
  88 }
  89
  90 int
  91 main(int argc, char *argv[])
  92 {
  93         static struct timespec delay = { 0, 100000000 };        /* 100ms */
  94         struct sched_param sp;
  95         pthread_t pt;
  96         cpuset_t *cs;
  97         int cpuid;
  98
  99         (void)setvbuf(stdout, NULL, _IOLBF, BUFSIZ);
 100
 101         if (geteuid() != 0) {
 102                 errx(1, "run me as root");
 103         }
 104         pthread_barrier_init(&barrier, NULL, 2);
 105         if (pthread_create(&pt, NULL, reader, NULL)) {
 106                 errx(1, "pthread_create failed");
 107         }
 108         if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
 109                 err(1, "mlockall");
 110         }
 111         if (signal(SIGINT, sigint)) {
 112                 err(1, "siginal");
 113         }
 114
 115         if (argc < 2) {
 116                 cs = cpuset_create();
 117                 if (cs == NULL) {
 118                         err(1, "cpuset_create");
 119                 }
 120                 cpuset_zero(cs);
 121                 cpuid = pthread_curcpu_np();
 122                 cpuset_set(cpuid, cs);
 123                 if (_sched_setaffinity(0, 0, cpuset_size(cs), cs) < 0) {
 124                         err(1, "_sched_setaffinity");
 125                 }
 126                 cpuset_destroy(cs);
 127         }
 128
 129         sp.sched_priority = sched_get_priority_max(SCHED_FIFO) - 2;
 130         if (pthread_setschedparam(pthread_self(), SCHED_FIFO, &sp)) {
 131                 errx(1, "pthread_setschedparam");
 132         }
 133         sp.sched_priority = sched_get_priority_max(SCHED_FIFO) - 1;
 134         if (pthread_setschedparam(pt, SCHED_FIFO, &sp)) {
 135                 errx(1, "pthread_setschedparam");
 136         }
 137
 138         do {
 139                 (void)pthread_barrier_wait(&barrier);
 140                 while (nanosleep(&delay, NULL) != 0) {
 141                         /* nothing */
 142                 }
 143                 clock_gettime(CLOCK_MONOTONIC, &start);
 144                 if (_lwp_unpark(lid, &lid) != 0) {
 145                         err(1, "_lwp_unpark");
 146                 }
 147         } while (!done);
 148
 149         printf("\nmin=%ldns, max=%ldns, mean=%ldns\n", min, max, sum / samples);
 150         return 0;
 151 }