oracular (3) pthread_getschedparam.3posix.gz

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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  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  specified  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.   It  is  unspecified  whether  the sched_ss_repl_period and sched_ss_init_budget values are
       stored as provided by this function or are rounded to align with the resolution of the clock being used.

       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_setschedparam() function shall fail if:

       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.

       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.

       EPERM  The caller does not have appropriate privileges 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.

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

       The following sections are informative.


EXAMPLES
       None.


APPLICATION USAGE
       None.


RATIONALE
       If an implementation detects use of a thread ID after the end of its lifetime, it is recommended that the
       function should fail and report an [ESRCH] error.


FUTURE DIRECTIONS
       None.


SEE ALSO
       pthread_setschedprio(), sched_getparam(), sched_getscheduler()

       The Base Definitions volume of POSIX.1‐2017, <pthread.h>, <sched.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .