.\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996

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.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>

.\"            First version written

.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>

.\"            revision

.\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>

.\"

.TH SCHED_SETPARAM 2 2017-09-15 "Linux" "Linux Programmer's Manual"

.SH NAME

sched_setparam, sched_getparam \- set and get scheduling parameters

.SH SYNOPSIS

.nf

.B #include <sched.h>

.PP

.BI "int sched_setparam(pid_t " pid ", const struct sched_param *" param );

.PP

.BI "int sched_getparam(pid_t " pid ", struct sched_param *" param );

.PP

\fBstruct sched_param {

    ...

    int \fIsched_priority\fB;

    ...

};

.fi

.SH DESCRIPTION

.BR sched_setparam ()

sets the scheduling parameters associated with the scheduling policy

for the process identified by \fIpid\fP.

If \fIpid\fP is zero, then

the parameters of the calling process are set.

The interpretation of

the argument \fIparam\fP depends on the scheduling

policy of the process identified by

.IR pid .

See

.BR sched (7)

for a description of the scheduling policies supported under Linux.

.PP

.BR sched_getparam ()

retrieves the scheduling parameters for the

process identified by \fIpid\fP.

If \fIpid\fP is zero, then the parameters

of the calling process are retrieved.

.PP

.BR sched_setparam ()

checks the validity of \fIparam\fP for the scheduling policy of the

thread.

The value \fIparam\->sched_priority\fP must lie within the

range given by

.BR sched_get_priority_min (2)

and

.BR sched_get_priority_max (2).

.PP

For a discussion of the privileges and resource limits related to

scheduling priority and policy, see

.BR sched (7).

.PP

POSIX systems on which

.BR sched_setparam ()

and

.BR sched_getparam ()

are available define

.B _POSIX_PRIORITY_SCHEDULING

in \fI<unistd.h>\fP.

.SH RETURN VALUE

On success,

.BR sched_setparam ()

and

.BR sched_getparam ()

return 0.

On error, \-1 is returned, and

.I errno

is set appropriately.

.SH ERRORS

.TP

.B EINVAL

Invalid arguments:

.I param

is NULL or

.I pid

is negative

.TP

.B EINVAL

.RB ( sched_setparam ())

The argument \fIparam\fP does not make sense for the current

scheduling policy.

.TP

.B EPERM

.RB ( sched_setparam ())

The calling process does not have appropriate privileges

(Linux: does not have the

.B CAP_SYS_NICE

capability).

.TP

.B ESRCH

The process whose ID is \fIpid\fP could not be found.

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008.

.SH NOTES

.PP

Scheduling parameters are in fact per-thread

attributes on Linux;

see

.BR sched (7).

.SH SEE ALSO

.ad l

.nh

.BR getpriority (2),

.BR nice (2),

.BR sched_get_priority_max (2),

.BR sched_get_priority_min (2),

.BR sched_getaffinity (2),

.BR sched_getscheduler (2),

.BR sched_setaffinity (2),

.BR sched_setattr (2),

.BR sched_setscheduler (2),

.BR setpriority (2),

.BR capabilities (7),

.BR sched (7)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.