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