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[thirdparty/man-pages.git] / man3 / pthread_attr_setschedparam.3

.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH PTHREAD_ATTR_SETSCHEDPARAM 3 2021-03-22 "Linux" "Linux Programmer's Manual"
.SH NAME
pthread_attr_setschedparam, pthread_attr_getschedparam \- set/get
scheduling parameter attributes in thread attributes object
.SH LIBRARY
POSIX threads library
.RI ( libpthread ", " \-lpthread )
.SH SYNOPSIS
.nf
.B #include <pthread.h>
.PP
.BI "int pthread_attr_setschedparam(pthread_attr_t *restrict " attr ,
.BI "                              const struct sched_param *restrict " param );
.BI "int pthread_attr_getschedparam(const pthread_attr_t *restrict " attr ,
.BI "                              struct sched_param *restrict " param );
.fi
.SH DESCRIPTION
The
.BR pthread_attr_setschedparam ()
function sets the scheduling parameter attributes of the
thread attributes object referred to by
.I attr
to the values specified in the buffer pointed to by
.IR param .
These attributes determine the scheduling parameters of
a thread created using the thread attributes object
.IR attr .
.PP
The
.BR pthread_attr_getschedparam ()
returns the scheduling parameter attributes of the thread attributes object
.I attr
in the buffer pointed to by
.IR param .
.PP
Scheduling parameters are maintained in the following structure:
.PP
.in +4n
.EX
struct sched_param {
    int sched_priority;     /* Scheduling priority */
};
.EE
.in
.PP
As can be seen, only one scheduling parameter is supported.
For details of the permitted ranges for scheduling priorities
in each scheduling policy, see
.BR sched (7).
.PP
In order for the parameter setting made by
.BR pthread_attr_setschedparam ()
to have effect when calling
.BR pthread_create (3),
the caller must use
.BR pthread_attr_setinheritsched (3)
to set the inherit-scheduler attribute of the attributes object
.I attr
to
.BR PTHREAD_EXPLICIT_SCHED .
.SH RETURN VALUE
On success, these functions return 0;
on error, they return a nonzero error number.
.SH ERRORS
.BR pthread_attr_setschedparam ()
can fail with the following error:
.TP
.B EINVAL
The priority specified in
.I param
does not make sense for the current scheduling policy of
.IR attr .
.PP
POSIX.1 also documents an
.B ENOTSUP
error for
.BR pthread_attr_setschedparam ().
This value is never returned on Linux
(but portable and future-proof applications should nevertheless
handle this error return value).
.\" .SH VERSIONS
.\" Available since glibc 2.0.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR pthread_attr_setschedparam (),
.BR pthread_attr_getschedparam ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
.SH NOTES
See
.BR pthread_attr_setschedpolicy (3)
for a list of the thread scheduling policies supported on Linux.
.SH EXAMPLES
See
.BR pthread_setschedparam (3).
.SH SEE ALSO
.ad l
.nh
.BR sched_get_priority_min (2),
.BR pthread_attr_init (3),
.BR pthread_attr_setinheritsched (3),
.BR pthread_attr_setschedpolicy (3),
.BR pthread_create (3),
.BR pthread_setschedparam (3),
.BR pthread_setschedprio (3),
.BR pthreads (7),
.BR sched (7)