pthread_setschedparam(3)   Library Functions Manual   pthread_setschedparam(3)

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       pthread_setschedparam, pthread_getschedparam -
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       <?><?><?><?><?> <?><?><?><?><?> POSIX (libpthread<?> -lpthread)

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       #include <pthread.h>

       int pthread_setschedparam(pthread_t thread, int policy,
                                 const struct sched_param *param);
       int pthread_getschedparam(pthread_t thread, int *restrict policy,
                                 struct sched_param *restrict param);

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       <?><?><?><?> <?><?><?><?><?><?> pthread_setschedparam()
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       <?><?><?><?><?> thread.

       <?><?><?><?> policy <?><?><?><?><?> <?><?><?><?><?><?><?>
       <?><?><?><?><?><?><?> <?><?> thread.  <?><?><?><?><?>
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       <?><?><?><?><?><?> <?><?> sched(7).

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       <?><?> param <?><?><?><?><?><?><?> <?><?><?><?><?><?><?>
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           struct sched_param {
               int sched_priority;     /* <?><?><?><?><?><?> <?><?><?><?><?><?><?> */
           };

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       <?><?><?><?><?> <?><?><?><?><?><?> pthread_getschedparam()
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       pthread_setschedprio(3) <?><?> pthread_create(3) <?><?><?><?> <?><?><?>
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              param <?><?><?> <?><?><?><?><?> <?><?><?><?><?><?><?> <?><?>
              policy.

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       +------------+------------------------------------+--------------------+
       |<?><?><?><?><?><?><?>|<?><?><?><?><?>            | <?><?><?><?><?><?> |
       +------------+------------------------------------+--------------------+
       |pthread_setschedparam(),|<?><?><?><?><?>         | MT-Safe            |
       |pthread_getschedparam()|<?><?><?><?><?><?>       |                    |
       +------------+------------------------------------+--------------------+
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       POSIX.1-2008.

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       glibc 2.0 POSIX.1-2001.

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       <?><?><?> PTHREAD_EXPLICIT_SCHED<?> <?><?><?> <?><?><?><?> <?><?>
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           $ su;      # Need privilege to set real-time scheduling policies
           Password:
           # ./a.out -mf10 -ar20 -i e;
           Scheduler settings of main thread
               policy=SCHED_FIFO, priority=10

           Scheduler settings in 'attr'
               policy=SCHED_RR, priority=20
               inheritsched is EXPLICIT

           Scheduler attributes of new thread
               policy=SCHED_RR, priority=20

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           # ./a.out -mf10 -ar20 -i i;
           Scheduler settings of main thread
               policy=SCHED_FIFO, priority=10

           Scheduler settings in 'attr'
               policy=SCHED_RR, priority=20
               inheritsched is INHERIT

           Scheduler attributes of new thread
               policy=SCHED_FIFO, priority=10

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       /* pthreads_sched_test.c */

       #include <err.h>
       #include <errno.h>
       #include <pthread.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <unistd.h>

       [[noreturn]]
       static void
       usage(char *prog_name, char *msg)
       {
           if (msg != NULL)
               fputs(msg, stderr);

           fprintf(stderr, "Usage: %s [options]\n", prog_name);
           fprintf(stderr, "Options are:\n");
       #define fpe(msg) fprintf(stderr, "\t%s", msg)          /* Shorter */
           fpe("-a<policy><prio> Set scheduling policy and priority in\n");
           fpe("                 thread attributes object\n");
           fpe("                 <policy> can be\n");
           fpe("                     f  SCHED_FIFO\n");
           fpe("                     r  SCHED_RR\n");
           fpe("                     o  SCHED_OTHER\n");
           fpe("-A               Use default thread attributes object\n");
           fpe("-i {e|i}         Set inherit scheduler attribute to\n");
           fpe("                 'explicit' or 'inherit'\n");
           fpe("-m<policy><prio> Set scheduling policy and priority on\n");
           fpe("                 main thread before pthread_create() call\n");
           exit(EXIT_FAILURE);
       }

       static int
       get_policy(char p, int *policy)
       {
           switch (p) {
           case 'f': *policy = SCHED_FIFO;     return 1;
           case 'r': *policy = SCHED_RR;       return 1;
           case 'o': *policy = SCHED_OTHER;    return 1;
           default:  return 0;
           }
       }

       static void
       display_sched_attr(int policy, const struct sched_param *param)
       {
           printf("    policy=%s, priority=%d\n",
                  (policy == SCHED_FIFO)  ? "SCHED_FIFO" :
                  (policy == SCHED_RR)    ? "SCHED_RR" :
                  (policy == SCHED_OTHER) ? "SCHED_OTHER" :
                  "???",
                  param->sched_priority);
       }

       static void
       display_thread_sched_attr(char *msg)
       {
           int policy, s;
           struct sched_param param;

           s = pthread_getschedparam(pthread_self(), &policy, &param);
           if (s != 0)
               errc(EXIT_FAILURE, s, "pthread_getschedparam");

           printf("%s\n", msg);
           display_sched_attr(policy, &param);
       }

       static void *
       thread_start(void *arg)
       {
           display_thread_sched_attr("Scheduler attributes of new thread");

           return NULL;
       }

       int
       main(int argc, char *argv[])
       {
           int s, opt, inheritsched, use_null_attrib, policy;
           pthread_t thread;
           pthread_attr_t attr;
           pthread_attr_t *attrp;
           char *attr_sched_str, *main_sched_str, *inheritsched_str;
           struct sched_param param;

           /* Process command-line options.  */

           use_null_attrib = 0;
           attr_sched_str = NULL;
           main_sched_str = NULL;
           inheritsched_str = NULL;

           while ((opt = getopt(argc, argv, "a:Ai:m:")) != -1) {
               switch (opt) {
               case 'a': attr_sched_str = optarg;      break;
               case 'A': use_null_attrib = 1;          break;
               case 'i': inheritsched_str = optarg;    break;
               case 'm': main_sched_str = optarg;      break;
               default:  usage(argv[0], "Unrecognized option\n");
               }
           }

           if (use_null_attrib
               && (inheritsched_str != NULL || attr_sched_str != NULL))
           {
               usage(argv[0], "Can't specify -A with -i or -a\n");
           }

           /* Optionally set scheduling attributes of main thread,
              and display the attributes.  */

           if (main_sched_str != NULL) {
               if (!get_policy(main_sched_str[0], &policy))
                   usage(argv[0], "Bad policy for main thread (-m)\n");
               param.sched_priority = strtol(&main_sched_str[1], NULL, 0);

               s = pthread_setschedparam(pthread_self(), policy, &param);
               if (s != 0)
                   errc(EXIT_FAILURE, s, "pthread_setschedparam");
           }

           display_thread_sched_attr("Scheduler settings of main thread");
           printf("\n");

           /* Initialize thread attributes object according to options.  */

           attrp = NULL;

           if (!use_null_attrib) {
               s = pthread_attr_init(&attr);
               if (s != 0)
                   errc(EXIT_FAILURE, s, "pthread_attr_init");
               attrp = &attr;
           }

           if (inheritsched_str != NULL) {
               if (inheritsched_str[0] == 'e')
                   inheritsched = PTHREAD_EXPLICIT_SCHED;
               else if (inheritsched_str[0] == 'i')
                   inheritsched = PTHREAD_INHERIT_SCHED;
               else
                   usage(argv[0], "Value for -i must be 'e' or 'i'\n");

               s = pthread_attr_setinheritsched(&attr, inheritsched);
               if (s != 0)
                   errc(EXIT_FAILURE, s, "pthread_attr_setinheritsched");
           }

           if (attr_sched_str != NULL) {
               if (!get_policy(attr_sched_str[0], &policy))
                   usage(argv[0], "Bad policy for 'attr' (-a)\n");
               param.sched_priority = strtol(&attr_sched_str[1], NULL, 0);

               s = pthread_attr_setschedpolicy(&attr, policy);
               if (s != 0)
                   errc(EXIT_FAILURE, s, "pthread_attr_setschedpolicy");
               s = pthread_attr_setschedparam(&attr, &param);
               if (s != 0)
                   errc(EXIT_FAILURE, s, "pthread_attr_setschedparam");
           }

           /* If we initialized a thread attributes object, display
              the scheduling attributes that were set in the object.  */

           if (attrp != NULL) {
               s = pthread_attr_getschedparam(&attr, &param);
               if (s != 0)
                   errc(EXIT_FAILURE, s, "pthread_attr_getschedparam");
               s = pthread_attr_getschedpolicy(&attr, &policy);
               if (s != 0)
                   errc(EXIT_FAILURE, s, "pthread_attr_getschedpolicy");

               printf("Scheduler settings in 'attr'\n");
               display_sched_attr(policy, &param);

               pthread_attr_getinheritsched(&attr, &inheritsched);
               printf("    inheritsched is %s\n",
                      (inheritsched == PTHREAD_INHERIT_SCHED)  ? "INHERIT" :
                      (inheritsched == PTHREAD_EXPLICIT_SCHED) ? "EXPLICIT" :
                      "???");
               printf("\n");
           }

           /* Create a thread that will display its scheduling attributes.  */

           s = pthread_create(&thread, attrp, &thread_start, NULL);
           if (s != 0)
               errc(EXIT_FAILURE, s, "pthread_create");

           /* Destroy unneeded thread attributes object.  */

           if (!use_null_attrib) {
             s = pthread_attr_destroy(&attr);
             if (s != 0)
                 errc(EXIT_FAILURE, s, "pthread_attr_destroy");
           }

           s = pthread_join(thread, NULL);
           if (s != 0)
               errc(EXIT_FAILURE, s, "pthread_join");

           exit(EXIT_SUCCESS);
       }

<?><?><?><?> <?><?><?><?><?>
       getrlimit(2), sched_get_priority_min(2), pthread_attr_init(3),
       pthread_attr_setinheritsched(3), pthread_attr_setschedparam(3),
       pthread_attr_setschedpolicy(3), pthread_create(3), pthread_self(3),
       pthread_setschedprio(3), pthreads(7), sched(7)

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       <kde-l10n-ar@kde.org>.


<?><?><?><?><?> <?><?><?><?> <?><?><?><?><?> 6.18
                          21 <?><?><?><?><?><?> 2025  pthread_setschedparam(3)