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 .