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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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PTHREAD...HEDPARAM(3P) POSIX Programmer's Manual PTHREAD...HEDPARAM(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.1‐2017, pthread.h(0p),
sched.h(0p)
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 .
IEEE/The Open Group 2017 PTHREAD...HEDPARAM(3P)
Pages that refer to this page: pthread.h(0p), pthread_setschedparam(3p), pthread_setschedprio(3p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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