PTHREAD_SETSCHEDPRIO(P) POSIX Programmer's Manual PTHREAD_SETSCHEDPRIO(P)NAMEpthread_setschedprio - dynamic thread scheduling parameters access
(REALTIME THREADS)
SYNOPSIS
#include <pthread.h>
int pthread_setschedprio(pthread_t thread, int prio);
DESCRIPTION
The pthread_setschedprio() function shall set the scheduling priority
for the thread whose thread ID is given by thread to the value given by
prio. See Scheduling Policies for a description on how this function
call affects the ordering of the thread in the thread list for its new
priority.
If the pthread_setschedprio() function fails, the scheduling priority
of the target thread shall not be changed.
RETURN VALUE
If successful, the pthread_setschedprio() function shall return zero;
otherwise, an error number shall be returned to indicate the error.
ERRORS
The pthread_setschedprio() function may fail if:
EINVAL The value of prio is invalid for the scheduling policy of the
specified thread.
ENOTSUP
An attempt was made to set the priority to an unsupported value.
EPERM The caller does not have the appropriate permission to set the
scheduling policy of the specified thread.
EPERM The implementation does not allow the application to modify the
priority to the value specified.
ESRCH The value specified by thread does not refer to an existing
thread.
The pthread_setschedprio() function shall not return an error code of
[EINTR].
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
The pthread_setschedprio() function provides a way for an application
to temporarily raise its priority and then lower it again, without hav‐
ing the undesired side effect of yielding to other threads of the same
priority. This is necessary if the application is to implement its own
strategies for bounding priority inversion, such as priority inheri‐
tance or priority ceilings. This capability is especially important if
the implementation does not support the Thread Priority Protection or
Thread Priority Inheritance options, but even if those options are sup‐
ported it is needed if the application is to bound priority inheritance
for other resources, such as semaphores.
The standard developers considered that while it might be preferable
conceptually to solve this problem by modifying the specification of
pthread_setschedparam(), it was too late to make such a change, as
there may be implementations that would need to be changed. Therefore,
this new function was introduced.
FUTURE DIRECTIONS
None.
SEE ALSO
Scheduling Policies , pthread_getschedparam() , the Base Definitions
volume of IEEE Std 1003.1-2001, <pthread.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 PTHREAD_SETSCHEDPRIO(P)
