PTHREAD_SETSCHEDPRIO(P) POSIX Programmer's Manual PTHREAD_SETSCHEDPRIO(P)
pthread_setschedprio - dynamic thread scheduling parameters access (REALTIME THREADS)
int pthread_setschedprio(pthread_t thread, int prio);
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.
If successful, the pthread_setschedprio() function shall return zero; otherwise, an error
number shall be returned to indicate the error.
The pthread_setschedprio() function may fail if:
EINVAL The value of prio is invalid for the scheduling policy of the specified thread.
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
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.
The pthread_setschedprio() function provides a way for an application to temporarily raise
its priority and then lower it again, without having the undesired side effect of yielding
to other threads of the same priority. This is necessary if the application is to imple-
ment its own strategies for bounding priority inversion, such as priority inheritance 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 supported it is needed if the application is to bound priority inheri-
tance 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. There-
fore, this new function was introduced.
Scheduling Policies , pthread_getschedparam() , the Base Definitions volume of
IEEE Std 1003.1-2001, <pthread.h>
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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 PTHREAD_SETSCHEDPRIO(P)