pthread_getschedparam

, pthread_setschedparam

- access dynamic thread scheduling parameters

Synopsis

cc –mt [ flag... ] file... [ library... ]
#include <pthread.h>

int pthread_getschedparam(pthread_t thread, int *restrict policy,
     struct sched_param *restrict param);

int pthread_setschedparam(pthread_t thread, int policy,
     const struct sched_param *param);

Description

The pthread_getschedparam() and pthread_setschedparam() functions allow the scheduling policy and scheduling parameters of individual threads within a multithreaded process to be retrieved and set. Supported policies are :

SCHED_OTHER

traditional time-sharing scheduling class

SCHED_FIFO

real-time class: run to completion

SCHED_RR

real-time class: round-robin

SCHED_IA

interactive time-sharing class

SCHED_FSS

fair-share scheduling class

SCHED_FX

fixed priority scheduling class

See pthreads(5). The affected scheduling parameter is the sched_priority member of the sched_param structure.

The pthread_getschedparam() function retrieves the scheduling policy and scheduling parameters for the thread whose thread ID is given by thread and stores those values in policy and param, respectively. The priority value returned from pthread_getschedparam() is the value specified by the most recent pthread_setschedparam() or pthread_create() call affecting the target thread, and does not reflect any temporary adjustments to its priority as a result of any priority inheritance or ceiling functions. The pthread_setschedparam() function sets the scheduling policy and associated scheduling parameters for the thread whose thread ID is given by thread to the policy and associated parameters provided in policy and param, respectively.

If the pthread_setschedparam() function fails, no scheduling parameters will be changed for the target thread.

Return Values

If successful, the pthread_getschedparam() and pthread_setschedparam() functions return 0. Otherwise, an error number is returned to indicate the error.

Errors

The pthread_getschedparam() and pthread_gsetschedparam() functions will fail if:

ESRCH

The value specified by thread does not refer to an existing thread.

The pthread_setschedparam() function will fail if:

EINVAL

The value specified by policy or one of the scheduling parameters associated with the scheduling policy policy is invalid.

EPERM

The caller does not have the appropriate permission to set either the scheduling parameters or the scheduling policy of the specified thread.

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

pthread_attr_init(3C), sched_getparam(3C), sched_get_priority_max(3C)sched_get_priority_max(3C), sched_get_priority_min(3C), sched_setparam(3C), sched_getscheduler(3C), sched_setscheduler(3C), attributes(5), pthreads(5), standards(5)