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SCHED_SETPARAM

Section: Linux Programmer's Manual (2)
Updated: 2017-09-15
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NAME

sched_setparam, sched_getparam - set and get scheduling parameters

SYNOPSIS

#include <sched.h>

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

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

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 calling process are set. The interpretation of the argument param depends on the scheduling policy of the process identified by pid. See sched(7) for a description of the scheduling policies supported under Linux.

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

sched_setparam() checks the validity of param for the scheduling policy of the thread. The value param->sched_priority must lie within the range given by sched_get_priority_min(2) and sched_get_priority_max(2).

For a discussion of the privileges and resource limits related to scheduling priority and policy, see sched(7).

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, and errno is set appropriately.

ERRORS

EINVAL: Invalid arguments: param is NULL or pid is negative
EINVAL: (sched_setparam()) The argument param does not make sense for the current scheduling policy.
EPERM: (sched_setparam()) 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.1-2001, POSIX.1-2008.

NOTES

Scheduling parameters are in fact per-thread attributes on Linux; see sched(7).

COLOPHON

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