SCHED_SETPARAM

sched_setparam, sched_getparam ? set and get scheduling parameters

#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;

...

};

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.

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

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

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.

POSIX.1b (formerly POSIX.4)

sched_setscheduler(2), sched_getscheduler(2), sched_get_priority_max(2), sched_get_priority_min(2), nice(2), setpriority(2), getpriority(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