1 /*
2 * Copyright (c) 1996 - 2000
3 * HD Associates, Inc. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by HD Associates, Inc
16 * 4. Neither the name of the author nor the names of any co-contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY HD ASSOCIATES AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL HD ASSOCIATES OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $FreeBSD: src/tools/regression/p1003_1b/fifo.c,v 1.1 2000/02/16 14:28:40 dufault Exp $
33 * $DragonFly: src/tools/regression/p1003_1b/fifo.c,v 1.3 2007/06/26 23:30:05 josepht Exp $
34 */
35 #include <unistd.h>
36 #include <stdlib.h>
37 #include <stdio.h>
38 #include <errno.h>
39 #include <err.h>
40 #include <fcntl.h>
41 #include <sys/types.h>
42 #include <sys/mman.h>
43 #include <sys/time.h>
44 #include <sys/sched.h>
45 #include <signal.h>
46
47 volatile int ticked;
48 #define CAN_USE_ALARMS
49
50 #ifdef CAN_USE_ALARMS
tick(int arg)51 void tick(int arg)
52 {
53 ticked = 1;
54 }
55 #endif
56
57 /* Fifo: Verify that fifo and round-robin scheduling seem to work.
58 *
59 * This tests:
60 * 1. That sched_rr_get_interval seems to work;
61 * 2. That FIFO scheduling doesn't seeem to be round-robin;
62 * 3. That round-robin scheduling seems to work.
63 *
64 */
65 static pid_t child;
tidyup(void)66 static void tidyup(void)
67 {
68 if (child)
69 kill(child, SIGHUP);
70 }
71
72 static double
tvsub(const struct timeval * a,const struct timeval * b)73 tvsub(const struct timeval *a, const struct timeval *b)
74 {
75 long sdiff;
76 long udiff;
77
78 sdiff = a->tv_sec - b->tv_sec;
79 udiff = a->tv_usec - b->tv_usec;
80
81 return (double)(sdiff * 1000000 + udiff) / 1e6;
82 }
83
fifo(int argc,char * argv[])84 int fifo(int argc, char *argv[])
85 {
86 int e = 0;
87 volatile long *p, pid;
88 int i;
89 struct sched_param fifo_param;
90 struct timespec interval;
91 #define MAX_RANAT 32
92 struct timeval ranat[MAX_RANAT];
93
94 #ifdef CAN_USE_ALARMS
95 static struct itimerval itimerval;
96 #endif
97
98 /* What is the round robin interval?
99 */
100
101 if (sched_rr_get_interval(0, &interval) == -1) {
102 perror("sched_rr_get_interval");
103 exit(errno);
104 }
105
106 #ifdef CAN_USE_ALARMS
107 signal(SIGALRM, tick);
108 #endif
109
110 fifo_param.sched_priority = 1;
111
112 p = (long *)mmap(0, sizeof(*p),
113 PROT_READ|PROT_WRITE, MAP_ANON|MAP_SHARED|MAP_INHERIT, -1, 0);
114
115 if (p == (long *)-1)
116 err(errno, "mmap");
117
118 *p = 0;
119
120 if (sched_setscheduler(0, SCHED_FIFO, &fifo_param) == -1)
121 {
122 perror("sched_setscheduler");
123 return -1;
124 }
125
126 pid = getpid();
127
128 if ((child = fork()) == 0)
129 {
130 /* Child process. Just keep setting the pointer to our
131 * PID. The parent will kill us when it wants to.
132 */
133
134 pid = getpid();
135 while (1)
136 *p = pid;
137 }
138 else
139 {
140 atexit(tidyup);
141 *p = pid;
142
143
144 ticked = 0;
145
146 #ifdef CAN_USE_ALARMS
147 /* Set an alarm for 250 times the round-robin interval.
148 * Then we will verify that a similar priority process
149 * will not run when we are using the FIFO scheduler.
150 */
151 itimerval.it_value.tv_usec = interval.tv_nsec / (1000 / 250);
152
153 itimerval.it_value.tv_sec = itimerval.it_value.tv_usec / 1000000;
154 itimerval.it_value.tv_usec %= 1000000;
155
156
157 if (setitimer(ITIMER_REAL, &itimerval, 0) == -1) {
158 perror("setitimer");
159 exit(errno);
160 }
161 #endif
162
163
164 gettimeofday(ranat, 0);
165 i = 1;
166 while (!ticked && i < MAX_RANAT)
167 if (*p == child) {
168 gettimeofday(ranat + i, 0);
169 *p = 0;
170 e = -1;
171 i++;
172 }
173
174 if (e) {
175 int j;
176
177 fprintf(stderr,
178 "SCHED_FIFO had erroneous context switches:\n");
179 for (j = 1; j < i; j++) {
180 fprintf(stderr, "%d %g\n", j,
181 tvsub(ranat + j, ranat + j - 1));
182 }
183 return e;
184 }
185
186 /* Switch to the round robin scheduler and the child
187 * should run within twice the interval.
188 */
189 if (sched_setscheduler(child, SCHED_RR, &fifo_param) == -1 ||
190 sched_setscheduler(0, SCHED_RR, &fifo_param) == -1)
191 {
192 perror("sched_setscheduler");
193 return -1;
194 }
195
196 e = -1;
197
198 ticked = 0;
199
200 #ifdef CAN_USE_ALARMS
201
202 /* Now we do want to see it run. But only set
203 * the alarm for twice the interval:
204 */
205 itimerval.it_value.tv_usec = interval.tv_nsec / 500;
206
207 if (setitimer(ITIMER_REAL, &itimerval, 0) == -1) {
208 perror("setitimer");
209 exit(errno);
210 }
211 #endif
212
213 for (i = 0; !ticked; i++)
214 if (*p == child) {
215 e = 0;
216 break;
217 }
218
219 if (e)
220 fprintf(stderr,"Child never ran when it should have.\n");
221 }
222
223 exit(e);
224 }
225
226 #ifdef STANDALONE_TESTS
main(int argc,char * argv[])227 int main(int argc, char *argv[]) { return fifo(argc, argv); }
228 #endif
229