pthread_getschedparam

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 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.1‐2008, <pthread.h>, <sched.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group.  (This is
       POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .



IEEE/The Open Group                  2013            PTHREAD_GETSCHEDPARAM(3P)