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.\" 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 2006-03-23 "Linux" "Linux Programmer's Manual"
.SH NAME
sched_setparam, sched_getparam \- set and get scheduling parameters
.SH SYNOPSIS
.nf
.B #include <sched.h>
.sp
.BI "int sched_setparam(pid_t " pid ", const struct sched_param *" param );
.sp
.BI "int sched_getparam(pid_t " pid ", struct sched_param *" param );
.sp
\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_setscheduler (2)
for a description of the scheduling policies supported under Linux.

.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.

.BR sched_setparam ()
checks the validity of \fIparam\fP for the scheduling policy of the
process.
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).

For a discussion of the privileges and resource limits related to
scheduling priority and policy, see
.BR sched_setscheduler (2).

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
The argument \fIparam\fP does not make sense for the current
scheduling policy.
.TP
.B EPERM
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.
.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_setscheduler (2),
.BR setpriority (2),
.BR capabilities (7)
.PP
.I Programming for the real world \- POSIX.4
by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0.
.SH COLOPHON
This page is part of release 3.44 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.