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



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

NAME
       pthread_getschedparam, pthread_setschedparam - dynamic thread  schedul-
       ing 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 pol-
       icy  and	 scheduling parameters for the thread whose thread ID is given
       by thread and shall store those values in  policy  and  param,  respec-
       tively.	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 speci-
       fied  sched_ss_repl_period shall be greater than or equal to the speci-
       fied 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  suc-
       ceed; if not, the function shall fail.

       If  the	pthread_setschedparam() function fails, the scheduling parame-
       ters 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 parame-
	      ters 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
	      specified 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 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_GETSCHEDPARAM(P)
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