redhat man page for sched_setparam

SCHED_SETPARAM(2)					     Linux Programmer's Manual						 SCHED_SETPARAM(2)

NAME
       sched_setparam, sched_getparam - set and get scheduling parameters

SYNOPSIS
       #include <sched.h>

       int sched_setparam(pid_t pid, const struct sched_param *p);

       int sched_getparam(pid_t pid, struct sched_param *p);

       struct sched_param {
	   ...
	   int sched_priority;
	   ...
       };

DESCRIPTION
       sched_setparam sets the scheduling parameters associated with the scheduling policy for the process identified by pid. If pid is zero, then
       the parameters of the current process are set. The interpretation of the parameter p depends on the selected policy. Currently, the follow-
       ing three scheduling policies are supported under Linux: SCHED_FIFO, SCHED_RR, and SCHED_OTHER.

       sched_getparam  retrieves  the  scheduling parameters for the process identified by pid. If pid is zero, then the parameters of the current
       process are retrieved.

       sched_setparam checks the validity of p for the scheduling policy of the process. The parameter p->sched_priority must lie within the range
       given by sched_get_priority_min and sched_get_priority_max.

       POSIX systems on which sched_setparam and sched_getparam are available define _POSIX_PRIORITY_SCHEDULING in <unistd.h>.

RETURN VALUE
       On success, sched_setparam and sched_getparam return 0.	On error, -1 is returned, errno is set appropriately.

ERRORS
       ESRCH  The process whose ID is pid could not be found.

       EPERM  The  calling  process  does  not have appropriate privileges. The process calling sched_setparam needs an effective uid equal to the
	      euid or uid of the process identified by pid, or it must be a superuser process.

       EINVAL The parameter p does not make sense for the current scheduling policy.

CONFORMING TO
       POSIX.1b (formerly POSIX.4)

SEE ALSO
       sched_setscheduler(2), sched_getscheduler(2),  sched_get_priority_max(2),  sched_get_priority_min(2),  nice(2),	setpriority(2),  getprior-
       ity(2),

       sched_setscheduler(2) has a description of the Linux scheduling scheme.

       Programming for the real world - POSIX.4 by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0
       IEEE Std 1003.1b-1993 (POSIX.1b standard)
       ISO/IEC 9945-1:1996

Linux 1.3.81							    1996-04-10							 SCHED_SETPARAM(2)