sched_setparam, sched_getparam - set and get scheduling parameters


#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; ... };


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_setscheduler(2) 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 process. 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_setscheduler(2).

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, and errno is set appropriately.


EINVAL The argument param 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.




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)

Programming for the real world - POSIX.4 by Bill O. Gallmeister, O’Reilly & Associates, Inc., ISBN 1-56592-074-0


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