PTHREAD_GETSCHEDPARAM(3P)				     POSIX Programmer's Manual					 PTHREAD_GETSCHEDPARAM(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       pthread_getschedparam, pthread_setschedparam - dynamic thread scheduling parameters access (REALTIME THREADS)

SYNOPSIS

       #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 shall, respectively, get and set the scheduling policy and parameters	of
       individual  threads  within  a multi-threaded process to be retrieved and set. For SCHED_FIFO and SCHED_RR, the only required member of the
       sched_param structure is the priority sched_priority. For SCHED_OTHER, the affected scheduling parameters are implementation-defined.

       The pthread_getschedparam() function shall retrieve the scheduling policy and scheduling parameters for the thread whose thread ID is given
       by thread and shall store those values in policy and param, respectively. The priority value returned from pthread_getschedparam() shall be
       the value specified by the most recent pthread_setschedparam(), pthread_setschedprio(),	or  pthread_create()  call  affecting  the  target
       thread.	It  shall  not reflect any temporary adjustments to its priority as a result of any priority inheritance or ceiling functions. The
       pthread_setschedparam() function shall set 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.

       The  policy  parameter  may  have  the value SCHED_OTHER, SCHED_FIFO, or SCHED_RR. The scheduling parameters for the SCHED_OTHER policy are
       implementation-defined. The SCHED_FIFO and SCHED_RR policies shall have a single scheduling parameter, priority.

       If _POSIX_THREAD_SPORADIC_SERVER is defined, then the policy argument may have  the  value  SCHED_SPORADIC,  with  the  exception  for  the
       pthread_setschedparam() function that if the scheduling policy was not SCHED_SPORADIC at the time of the call, it is implementation-defined
       whether the function is supported; in other words, the implementation need not allow the application to dynamically change  the	scheduling
       policy  to SCHED_SPORADIC. The sporadic server scheduling policy has the associated parameters sched_ss_low_priority, sched_ss_repl_period,
       sched_ss_init_budget, sched_priority, and sched_ss_max_repl. The specified sched_ss_repl_period shall be greater than or equal to the spec-
       ified sched_ss_init_budget for the function to succeed; if it is not, then the function shall fail. The value of sched_ss_max_repl shall be
       within the inclusive range [1, {SS_REPL_MAX}] for the function to succeed; if not, the function shall fail.

       If the pthread_setschedparam() function fails, the scheduling parameters shall not be changed for the target thread.

RETURN VALUE

       If successful, the pthread_getschedparam() and pthread_setschedparam() functions shall return zero; otherwise, an  error  number  shall	be
       returned to indicate the error.

ERRORS

       The pthread_getschedparam() function may fail if:

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

       The pthread_setschedparam() function may fail if:

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

       ENOTSUP
	      An attempt was made to set the policy or scheduling parameters to an unsupported value.

       ENOTSUP
	      An  attempt  was	made  to  dynamically change the scheduling policy to SCHED_SPORADIC, and the implementation does not support this
	      change.

       EPERM  The caller does not have the appropriate permission to set either the scheduling parameters or the scheduling policy of  the  speci-
	      fied thread.

       EPERM  The implementation does not allow the application to modify one of the parameters to the value specified.

       ESRCH  The value specified by thread does not refer to a existing thread.

       These functions shall not return an error code of [EINTR].

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       pthread_setschedprio(), sched_getparam(), sched_getscheduler(), the Base Definitions volume of IEEE Std 1003.1-2001, <pthread.h>, <sched.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- 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_GETSCHEDPARAM(3P)