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PTHREAD_GETSCHEDPARAM(3P) POSIX Programmer's ManualPTHREAD_GETSCHEDPARAM(3P)
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.
pthread_getschedparam, pthread_setschedparam — dynamic thread
scheduling parameters access (REALTIME THREADS)
#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);
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.
If successful, the pthread_getschedparam() and
pthread_setschedparam() functions shall return zero; otherwise, an
error number shall be returned to indicate the error.
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.
None.
None.
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.
None.
pthread_setschedprio(3p), sched_getparam(3p), sched_getscheduler(3p)
The Base Definitions volume of POSIX.1‐2008, pthread.h(0p),
sched.h(0p)
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)
Pages that refer to this page: pthread.h(0p), pthread_setschedparam(3p), pthread_setschedprio(3p)