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 implementation 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 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

       <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, Copyright (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.opengroup.org/unix/online.html .