tools/regression/p1003_1b/sched.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-4-Clause
   3  *
   4  * Copyright (c) 1996-1999
   5  *      HD Associates, Inc.  All rights reserved.
   6  *
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   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  * 3. All advertising materials mentioning features or use of this software
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  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
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  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL HD ASSOCIATES OR CONTRIBUTORS BE LIABLE
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  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
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  35
  36 /* XXX: The spec says that if _POSIX_C_SOURCE is defined then
  37  *      _POSIX_SOURCE is ignored.  However, this is similar to
  38  *      the code in the O'Reilly "POSIX.4" book
  39  */
  40
  41 #define _POSIX_VERSION 199309L
  42 #define _POSIX_SOURCE
  43 #define _POSIX_C_SOURCE 199309L
  44
  45 #include <sys/mman.h>
  46 #include <errno.h>
  47 #include <fcntl.h>
  48 #include <limits.h>
  49 #include <sched.h>
  50 #include <stdio.h>
  51 #define __XSI_VISIBLE 1
  52 #include <stdlib.h>
  53 #undef __XSI_VISIBLE
  54 #include <string.h>
  55 #include <unistd.h>
  56
  57 #include "prutil.h"
  58
  59 static FILE *verbose;
  60
  61 static void
  62 checkpris(int sched)
  63 {
  64         int smin;
  65         int smax;
  66
  67         errno = 0;
  68
  69         if ( (smin = sched_get_priority_min(sched)) == -1 && errno)
  70                 quit("sched_get_priority_min");
  71
  72         if ( (smax = sched_get_priority_max(sched)) == -1 && errno)
  73                 quit("sched_get_priority_max");
  74
  75         if (smax - smin + 1 < 32 || smax < smin) {
  76                 fprintf(stderr, "Illegal priority range for %s: %d to %d\n",
  77                 sched_text(sched), smin, smax);
  78                 exit(-1);
  79         }
  80
  81         if (verbose)
  82                 fprintf(verbose, "%12s: sched_min %2d sched_max %2d\n",
  83                 sched_text(sched), smin, smax);
  84 }
  85
  86 /* Set "try_anyway" to quit if you don't want to go on when
  87  * it doesn't look like something should work.
  88  */
  89 static void try_anyway(const char *s)
  90 {
  91         fputs(s, stderr);
  92         fprintf(stderr, "(trying anyway)\n");
  93         errno = 0;
  94 }
  95
  96 static void q(int line, int code, const char *text)
  97 {
  98         if (code == -1)
  99         {
 100                 fprintf(stderr, "Error at line %d:\n", line);
 101                 perror(text);
 102                 exit(errno);
 103         }
 104 }
 105
 106 int sched(int ac, char *av[])
 107 {
 108         int fifo_schedmin, fifo_schedmax;
 109         int i;
 110         struct sched_param rt_param;
 111         int n_instances = 10;
 112         int sched;
 113
 114         verbose = 0;
 115
 116 #if _POSIX_VERSION < 199309
 117         try_anyway("The _POSIX_VERSION predates P1003.1B\n");
 118 #endif
 119
 120 #if !defined(_POSIX_PRIORITY_SCHEDULING)
 121         try_anyway(
 122         "The environment does not claim to support Posix scheduling.\n");
 123 #endif
 124
 125         /* Is priority scheduling configured?
 126          */
 127         errno = 0;
 128         if (sysconf(_SC_PRIORITY_SCHEDULING) == -1) {
 129                 if (errno != 0) {
 130                         /* This isn't valid - may be a standard violation
 131                          */
 132                         quit("(should not happen) sysconf(_SC_PRIORITY_SCHEDULING)");
 133                 }
 134                 else {
 135                         try_anyway(
 136                         "The environment does not have run-time "
 137                         "support for Posix scheduling.\n");
 138                 }
 139         }
 140
 141         /* Check that the priorities seem reasonable.
 142          */
 143
 144         checkpris(SCHED_FIFO);
 145         checkpris(SCHED_RR);
 146         checkpris(SCHED_OTHER);
 147
 148 /* BSD extensions?
 149  */
 150 #if defined(SCHED_IDLE)
 151         checkpris(SCHED_IDLE);
 152 #endif
 153
 154         fifo_schedmin = sched_get_priority_min(SCHED_FIFO);
 155         fifo_schedmax = sched_get_priority_max(SCHED_FIFO);
 156
 157         /* Make sure we can do some basic schedule switching:
 158          */
 159         {
 160                 struct sched_param orig_param, shouldbe;
 161                 int orig_scheduler = sched_is(__LINE__, &orig_param, -1);
 162
 163                 if (verbose)
 164                         fprintf(verbose,
 165                         "The original scheduler is %s and the priority is %d.\n",
 166                         sched_text(orig_scheduler), orig_param.sched_priority);
 167
 168                 /* Basic check: Try to set current settings:
 169                  */
 170                 q(__LINE__, sched_setscheduler(0, orig_scheduler, &orig_param),
 171                         "sched_setscheduler: Can't set original scheduler");
 172
 173                 rt_param.sched_priority = fifo_schedmin;
 174
 175                 q(__LINE__, sched_setscheduler(0, SCHED_FIFO, &rt_param),
 176                 "sched_setscheduler SCHED_FIFO");
 177
 178                 (void)sched_is(__LINE__, 0, SCHED_FIFO);
 179
 180                 q(__LINE__, sched_getparam(0, &shouldbe), "sched_getparam");
 181
 182                 if (shouldbe.sched_priority != fifo_schedmin)
 183                         quit("sched_setscheduler wrong priority (min)");
 184
 185                 rt_param.sched_priority = fifo_schedmin;
 186
 187                 q(__LINE__, sched_setparam(0, &rt_param),
 188                         "sched_setparam to fifo_schedmin");
 189
 190                 rt_param.sched_priority = fifo_schedmin + 1;
 191
 192                 q(__LINE__, sched_setparam(0, &rt_param),
 193                         "sched_setparam to fifo_schedmin + 1");
 194
 195                 q(__LINE__, sched_getparam(0, &shouldbe),
 196                         "sched_getparam");
 197
 198                 if (shouldbe.sched_priority != fifo_schedmin + 1)
 199                         quit("sched_setscheduler wrong priority (min + 1)");
 200
 201                 q(__LINE__, sched_setscheduler(0, SCHED_RR, &rt_param),
 202                         "sched_setscheduler SCHED_RR");
 203
 204                 (void)sched_is(__LINE__, 0, SCHED_RR);
 205
 206                 q(__LINE__, sched_setscheduler(0, orig_scheduler, &orig_param),
 207                         "sched_setscheduler restoring original scheduler");
 208
 209                 (void)sched_is(__LINE__, 0, orig_scheduler);
 210         }
 211
 212
 213         {
 214                 char nam[] = "P1003_1b_schedXXXXXX";
 215                 int fd;
 216                 pid_t p;
 217                 pid_t *lastrun;
 218
 219                 fd = mkstemp(nam);
 220                 if (fd == -1)
 221                         q(__LINE__, errno, "mkstemp failed");
 222
 223                 (void)unlink(nam);
 224
 225                 p = (pid_t)0;
 226
 227                 write(fd, &p, sizeof(p));
 228
 229                 q(__LINE__,  (int)(lastrun = mmap(0, sizeof(*lastrun), PROT_READ|PROT_WRITE,
 230                 MAP_SHARED, fd, 0)), "mmap");
 231
 232                 /* Set our priority at the highest:
 233                  */
 234                 sched = SCHED_FIFO;
 235                 rt_param.sched_priority = fifo_schedmax;
 236                 q(__LINE__, sched_setscheduler(0, sched, &rt_param),
 237                 "sched_setscheduler sched");
 238
 239                 for (i = 0; i < n_instances; i++)
 240                 {
 241                         pid_t me;
 242
 243                         /* XXX This is completely bogus.  The children never run.
 244                          */
 245                         if ((me = fork()) != 0)
 246                         {
 247                                 /* Parent.
 248                                  */
 249                                 (void)sched_is(__LINE__, 0, sched);
 250
 251                                 /* Lower our priority:
 252                                  */
 253                                 rt_param.sched_priority--;
 254
 255                                 q(__LINE__, sched_setscheduler(0, sched, &rt_param),
 256                                 "sched_setscheduler sched");
 257
 258                                 while (1)
 259                                 {
 260                                         q(__LINE__, sched_getparam(0, &rt_param), "sched_getparam");
 261
 262                                         rt_param.sched_priority--;
 263
 264
 265                                         if (rt_param.sched_priority < fifo_schedmin)
 266                                                 exit(0);
 267
 268                                         *lastrun = me;
 269                                         q(__LINE__, sched_setparam(0, &rt_param), "sched_setparam");
 270
 271                                         if (*lastrun == me)
 272                                         {
 273                                                 /* The child will run twice
 274                                                  * at  the end:
 275                                                  */
 276                                                 if (!me || rt_param.sched_priority != 0)
 277                                                 {
 278                                                         fprintf(stderr,
 279                                                         "ran process %ld twice at priority %d\n",
 280                                                         (long)me, rt_param.sched_priority + 1);
 281                                                         exit(-1);
 282                                                 }
 283                                         }
 284                                 }
 285                         }
 286                 }
 287         }
 288
 289         return 0;
 290 }
 291 #ifdef STANDALONE_TESTS
 292 int main(int argc, char *argv[]) { return sched(argc, argv); }
 293 #endif