1 /* $NetBSD: latency2.c,v 1.4 2009/01/28 21:52:49 ad 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
sigint(int junk)58 sigint(int junk)
59 {
60
61 done = 1;
62 }
63
64 static void *
reader(void * cookie)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
main(int argc,char * argv[])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 }
152