PTHREAD_SETSCHEDPRIO(P)    POSIX Programmer's Manual   PTHREAD_SETSCHEDPRIO(P)



NAME
       pthread_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)