1 /*
2 * Copyright (c) 1996-1999
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 * $FreeBSD$
32 *
33 */
34
35 /* XXX: The spec says that if _POSIX_C_SOURCE is defined then
36 * _POSIX_SOURCE is ignored. However, this is similar to
37 * the code in the O'Reilly "POSIX.4" book
38 */
39
40 #define _POSIX_VERSION 199309L
41 #define _POSIX_SOURCE
42 #define _POSIX_C_SOURCE 199309L
43
44 #include <sys/mman.h>
45 #include <errno.h>
46 #include <fcntl.h>
47 #include <limits.h>
48 #include <sched.h>
49 #include <stdio.h>
50 #define __XSI_VISIBLE 1
51 #include <stdlib.h>
52 #undef __XSI_VISIBLE
53 #include <string.h>
54 #include <unistd.h>
55
56 #include "prutil.h"
57
58 static FILE *verbose;
59
60 static void
checkpris(int sched)61 checkpris(int sched)
62 {
63 int smin;
64 int smax;
65
66 errno = 0;
67
68 if ( (smin = sched_get_priority_min(sched)) == -1 && errno)
69 quit("sched_get_priority_min");
70
71 if ( (smax = sched_get_priority_max(sched)) == -1 && errno)
72 quit("sched_get_priority_max");
73
74 if (smax - smin + 1 < 32 || smax < smin) {
75 fprintf(stderr, "Illegal priority range for %s: %d to %d\n",
76 sched_text(sched), smin, smax);
77 exit(-1);
78 }
79
80 if (verbose)
81 fprintf(verbose, "%12s: sched_min %2d sched_max %2d\n",
82 sched_text(sched), smin, smax);
83 }
84
85 /* Set "try_anyway" to quit if you don't want to go on when
86 * it doesn't look like something should work.
87 */
try_anyway(const char * s)88 static void try_anyway(const char *s)
89 {
90 fputs(s, stderr);
91 fprintf(stderr, "(trying anyway)\n");
92 errno = 0;
93 }
94
q(int line,int code,const char * text)95 static void q(int line, int code, const char *text)
96 {
97 if (code == -1)
98 {
99 fprintf(stderr, "Error at line %d:\n", line);
100 perror(text);
101 exit(errno);
102 }
103 }
104
sched(int ac,char * av[])105 int sched(int ac, char *av[])
106 {
107 int fifo_schedmin, fifo_schedmax;
108 int i;
109 struct sched_param rt_param;
110 int n_instances = 10;
111 int sched;
112
113 verbose = 0;
114
115 #if _POSIX_VERSION < 199309
116 try_anyway("The _POSIX_VERSION predates P1003.1B\n");
117 #endif
118
119 #if !defined(_POSIX_PRIORITY_SCHEDULING)
120 try_anyway(
121 "The environment does not claim to support Posix scheduling.\n");
122 #endif
123
124 /* Is priority scheduling configured?
125 */
126 errno = 0;
127 if (sysconf(_SC_PRIORITY_SCHEDULING) == -1) {
128 if (errno != 0) {
129 /* This isn't valid - may be a standard violation
130 */
131 quit("(should not happen) sysconf(_SC_PRIORITY_SCHEDULING)");
132 }
133 else {
134 try_anyway(
135 "The environment does not have run-time "
136 "support for Posix scheduling.\n");
137 }
138 }
139
140 /* Check that the priorities seem reasonable.
141 */
142
143 checkpris(SCHED_FIFO);
144 checkpris(SCHED_RR);
145 checkpris(SCHED_OTHER);
146
147 /* BSD extensions?
148 */
149 #if defined(SCHED_IDLE)
150 checkpris(SCHED_IDLE);
151 #endif
152
153 fifo_schedmin = sched_get_priority_min(SCHED_FIFO);
154 fifo_schedmax = sched_get_priority_max(SCHED_FIFO);
155
156 /* Make sure we can do some basic schedule switching:
157 */
158 {
159 struct sched_param orig_param, shouldbe;
160 int orig_scheduler = sched_is(__LINE__, &orig_param, -1);
161
162 if (verbose)
163 fprintf(verbose,
164 "The original scheduler is %s and the priority is %d.\n",
165 sched_text(orig_scheduler), orig_param.sched_priority);
166
167 /* Basic check: Try to set current settings:
168 */
169 q(__LINE__, sched_setscheduler(0, orig_scheduler, &orig_param),
170 "sched_setscheduler: Can't set original scheduler");
171
172 rt_param.sched_priority = fifo_schedmin;
173
174 q(__LINE__, sched_setscheduler(0, SCHED_FIFO, &rt_param),
175 "sched_setscheduler SCHED_FIFO");
176
177 (void)sched_is(__LINE__, 0, SCHED_FIFO);
178
179 q(__LINE__, sched_getparam(0, &shouldbe), "sched_getparam");
180
181 if (shouldbe.sched_priority != fifo_schedmin)
182 quit("sched_setscheduler wrong priority (min)");
183
184 rt_param.sched_priority = fifo_schedmin;
185
186 q(__LINE__, sched_setparam(0, &rt_param),
187 "sched_setparam to fifo_schedmin");
188
189 rt_param.sched_priority = fifo_schedmin + 1;
190
191 q(__LINE__, sched_setparam(0, &rt_param),
192 "sched_setparam to fifo_schedmin + 1");
193
194 q(__LINE__, sched_getparam(0, &shouldbe),
195 "sched_getparam");
196
197 if (shouldbe.sched_priority != fifo_schedmin + 1)
198 quit("sched_setscheduler wrong priority (min + 1)");
199
200 q(__LINE__, sched_setscheduler(0, SCHED_RR, &rt_param),
201 "sched_setscheduler SCHED_RR");
202
203 (void)sched_is(__LINE__, 0, SCHED_RR);
204
205 q(__LINE__, sched_setscheduler(0, orig_scheduler, &orig_param),
206 "sched_setscheduler restoring original scheduler");
207
208 (void)sched_is(__LINE__, 0, orig_scheduler);
209 }
210
211
212 {
213 char nam[] = "P1003_1b_schedXXXXXX";
214 int fd;
215 pid_t p;
216 pid_t *lastrun;
217
218 fd = mkstemp(nam);
219 if (fd == -1)
220 q(__LINE__, errno, "mkstemp failed");
221
222 (void)unlink(nam);
223
224 p = (pid_t)0;
225
226 write(fd, &p, sizeof(p));
227
228 q(__LINE__, (int)(lastrun = mmap(0, sizeof(*lastrun), PROT_READ|PROT_WRITE,
229 MAP_SHARED, fd, 0)), "mmap");
230
231 /* Set our priority at the highest:
232 */
233 sched = SCHED_FIFO;
234 rt_param.sched_priority = fifo_schedmax;
235 q(__LINE__, sched_setscheduler(0, sched, &rt_param),
236 "sched_setscheduler sched");
237
238 for (i = 0; i < n_instances; i++)
239 {
240 pid_t me;
241
242 /* XXX This is completely bogus. The children never run.
243 */
244 if ((me = fork()) != 0)
245 {
246 /* Parent.
247 */
248 (void)sched_is(__LINE__, 0, sched);
249
250 /* Lower our priority:
251 */
252 rt_param.sched_priority--;
253
254 q(__LINE__, sched_setscheduler(0, sched, &rt_param),
255 "sched_setscheduler sched");
256
257 while (1)
258 {
259 q(__LINE__, sched_getparam(0, &rt_param), "sched_getparam");
260
261 rt_param.sched_priority--;
262
263
264 if (rt_param.sched_priority < fifo_schedmin)
265 exit(0);
266
267 *lastrun = me;
268 q(__LINE__, sched_setparam(0, &rt_param), "sched_setparam");
269
270 if (*lastrun == me)
271 {
272 /* The child will run twice
273 * at the end:
274 */
275 if (!me || rt_param.sched_priority != 0)
276 {
277 fprintf(stderr,
278 "ran process %ld twice at priority %d\n",
279 (long)me, rt_param.sched_priority + 1);
280 exit(-1);
281 }
282 }
283 }
284 }
285 }
286 }
287
288 return 0;
289 }
290 #ifdef STANDALONE_TESTS
main(int argc,char * argv[])291 int main(int argc, char *argv[]) { return sched(argc, argv); }
292 #endif
293