pthread_setscheduler(3thr)pthread_setscheduler(3thr)Namepthread_setscheduler - Changes the current scheduling policy and prior‐
ity of a thread.
Syntax
#include <pthread.h>
int pthread_setscheduler (thread, scheduler, priority)
pthread_t thread;
int scheduler;
int priority;
Arguments
thread Thread whose scheduling policy is to be changed.
scheduler
New scheduling policy value for the thread specified in thread.
(Policies listed on the same line are equivalent.) Valid values
are as follows:
SCHED_FIFO
SCHED_RR
SCHED_FG_NP or SCHED_OTHER
SCHED_BG_NP
priority
New priority value of the thread specified in thread. The pri‐
ority attribute is dependent upon scheduling policy. Valid
values fall within one of the following three ranges.
Low High
PRI_FIFO_MIN PRI_FIFO_MAX
PRI_RR_MIN PRI_RR_MAX
PRI_OTHER_MIN PRI_OTHER_MAX
PRI_FG_MIN_NP PRI_FG_MAX_NP
PRI_BG_MIN_NP PRI_BG_MAX_NP
If you create a new thread without specifying a threads attributes
object that contains a changed priority attribute, the default priority
of the newly created thread is the midpoint between PRI_OTHER_MIN and
PRI_OTHER_MAX (the midpoint between the minimum and the maximum for the
SCHED_OTHER policy).
Description
This routine changes the current scheduling policy and priority of a
thread. Call this routine to change both the priority and scheduling
policy of a thread at the same time. To change only the priority, call
the pthread_setprio routine.
A thread changes its own scheduling policy and priority by using the
identifier returned by pthread_self. Changing the scheduling policy or
priority, or both, of a thread can cause it to start executing or to be
preempted by another thread.
This routine is different from pthread_attr_setprio and
pthread_attr_setsched because those routines set the priority and
scheduling policy attributes that are used to establish the priority
and scheduling policy of a new thread when it is created. This rou‐
tine, however, changes the priority and scheduling policy of an exist‐
ing thread.
Return Values
If an error condition occurs, this routine returns -1 and sets errno to
the corresponding error value. Possible return values are as follows.
Return Error Description
0 Successful comple‐
tion.
-1 [EINVAL] The value specified
by thread is
invalid.
-1 [ENOTSUP] An attempt is made
to set the policy
to an unsupported
value.
-1 [ESRCH] The value specified
by thread does not
refer to an exist‐
ing thread.
-1 [EPERM] The caller does not
have the appropri‐
ate privileges to
set the priority of
the specified
thread.
pthread_setscheduler(3thr)
