PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       sched.h — execution scheduling

SYNOPSIS

       #include <sched.h>

DESCRIPTION

       The <sched.h> header shall define the pid_t type as described in <sys/types.h>.

       The <sched.h> header shall define the time_t type as described in <sys/types.h>.

       The <sched.h> header shall define the timespec structure as described in <time.h>.

       The  <sched.h>  header  shall  define  the  sched_param structure, which shall include the
       scheduling parameters required for implementation of  each  supported  scheduling  policy.
       This structure shall include at least the following member:

           int       sched_priority        Process or thread execution scheduling priority.

       The  sched_param  structure  defined  in  <sched.h> shall include the following members in
       addition to those specified above:

           int             sched_ss_low_priority Low scheduling priority for
                                                 sporadic server.
           struct timespec sched_ss_repl_period  Replenishment period for
                                                 sporadic server.
           struct timespec sched_ss_init_budget  Initial budget for sporadic server.
           int             sched_ss_max_repl     Maximum pending replenishments for
                                                 sporadic server.

       Each process or thread is controlled by an  associated  scheduling  policy  and  priority.
       Associated  with  each  policy  is  a priority range. Each policy definition specifies the
       minimum priority range for that policy. The priority ranges for each  policy  may  overlap
       the priority ranges of other policies.

       Four  scheduling  policies  are  defined; others may be defined by the implementation. The
       four standard policies are indicated by the values of the following symbolic constants:

       SCHED_FIFO    First in-first out (FIFO) scheduling policy.

       SCHED_RR      Round robin scheduling policy.

       SCHED_SPORADIC
                     Sporadic server scheduling policy.

       SCHED_OTHER   Another scheduling policy.

       The values of these constants are distinct.

       The following shall be declared as functions and may also be defined as  macros.  Function
       prototypes shall be provided.

           int    sched_get_priority_max(int);
           int    sched_get_priority_min(int);
           int    sched_getparam(pid_t, struct sched_param *);
           int    sched_getscheduler(pid_t);
           int    sched_rr_get_interval(pid_t, struct timespec *);
           int    sched_setparam(pid_t, const struct sched_param *);
           int    sched_setscheduler(pid_t, int, const struct sched_param *);
           int    sched_yield(void);

       Inclusion of the <sched.h> header may make visible all symbols from the <time.h> header.

       The following sections are informative.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       <sys_types.h>, <time.h>

       The  System Interfaces volume of POSIX.1‐2017, sched_get_priority_max(), sched_getparam(),
       sched_getscheduler(),  sched_rr_get_interval(),  sched_setparam(),   sched_setscheduler(),
       sched_yield()

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by
       the Institute of Electrical and Electronics Engineers, Inc and The  Open  Group.   In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .