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 following 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. For a discussion of the privileges and resource limits related to scheduling priority and policy, see sched_setscheduler(2). 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

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

EPERM
    The calling process does not have appropriate privileges (Linux: does not have the CAP_SYS_NICE capability).

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

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

SEE ALSO
getpriority(2), nice(2), sched_get_priority_max(2), sched_get_priority_min(2), sched_getaffinity(2), sched_getscheduler(2), sched_setaffinity(2), sched_setscheduler(2), setpriority(2), capabilities(7)

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