<sched.h>(0P)                                       POSIX Programmer's Manual                                      <sched.h>(0P)



NAME
       sched.h - execution scheduling (REALTIME)

SYNOPSIS
       #include <sched.h>

DESCRIPTION
       The <sched.h> header shall define the sched_param structure, which contains the scheduling parameters required for imple-
       mentation of each supported scheduling policy. This structure shall contain at least the following member:


              int       sched_priority        Process execution scheduling priority.

       In addition, if _POSIX_SPORADIC_SERVER or _POSIX_THREAD_SPORADIC_SERVER is defined, the sched_param structure defined  in
       <sched.h> shall contain 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  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 indi-
       cated 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
       <time.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                 <sched.h>(0P)