2004-11-03 13:51:07 +00:00
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.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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.\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996
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.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, write to the Free
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.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
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.\" USA.
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.\"
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.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>
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.\" First version written
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.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
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.\" revision
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2004-11-03 14:43:40 +00:00
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.\" Modified 2004-05-27 by Michael Kerrisk <mtk-manpages@gmx.net>
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2004-11-03 13:51:07 +00:00
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.\"
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.TH SCHED_SETPARAM 2 2004-05-27 "Linux 2.6.6" "Linux Programmer's Manual"
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.SH NAME
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sched_setparam, sched_getparam \- set and get scheduling parameters
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.SH SYNOPSIS
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.B #include <sched.h>
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.sp
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\fBint sched_setparam(pid_t \fIpid\fB, const struct sched_param *\fIp\fB);
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.sp
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\fBint sched_getparam(pid_t \fIpid\fB, struct sched_param *\fIp\fB);
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.sp
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.nf
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.ta 4n
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\fBstruct sched_param {
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...
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int \fIsched_priority\fB;
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...
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};
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.ta
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.fi
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.SH DESCRIPTION
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.B sched_setparam
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sets the scheduling parameters associated with the scheduling policy
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for the process identified by \fIpid\fR. If \fIpid\fR is zero, then
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the parameters of the current process are set. The interpretation of
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the parameter \fIp\fR depends on the selected policy. Currently, the
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following three scheduling policies are supported under Linux:
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.IR SCHED_FIFO ,
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.IR SCHED_RR ,
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and
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2005-07-19 15:36:19 +00:00
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.IR SCHED_OTHER .
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2004-11-03 13:51:07 +00:00
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.B sched_getparam
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retrieves the scheduling parameters for the
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process identified by \fIpid\fR. If \fIpid\fR is zero, then the parameters
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of the current process are retrieved.
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.B sched_setparam
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checks the validity of \fIp\fR for the scheduling policy of the
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process. The parameter \fIp->sched_priority\fR must lie within the
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range given by \fBsched_get_priority_min\fR and
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\fBsched_get_priority_max\fR.
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POSIX systems on which
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.B sched_setparam
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and
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.B sched_getparam
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are available define
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.I _POSIX_PRIORITY_SCHEDULING
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in <unistd.h>.
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.SH "RETURN VALUE"
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On success,
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.BR sched_setparam
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and
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.BR sched_getparam
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return 0.
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On error, \-1 is returned,
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.I errno
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is set appropriately.
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.SH ERRORS
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.TP
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.B EINVAL
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The parameter \fIp\fR does not make sense for the current
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scheduling policy.
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.TP
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.B EPERM
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The calling process does not have appropriate privileges.
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A process calling
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.BR sched_setparam
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needs an effective user ID equal to the user ID or effective user ID
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of the process identified by
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.IR pid ,
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or (Linux) it must have the
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CAP_SYS_NICE
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capability.
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.TP
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.B ESRCH
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The process whose ID is \fIpid\fR could not be found.
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.SH "CONFORMING TO"
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POSIX.1b (formerly POSIX.4)
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.SH "SEE ALSO"
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.BR getpriority (2),
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.BR nice (2),
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.BR sched_get_priority_max (2),
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.BR sched_get_priority_min (2),
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.BR sched_getaffinity (2),
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.BR sched_getscheduler (2),
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.BR sched_setaffinity (2),
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.BR sched_setscheduler (2),
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.BR setpriority (2),
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.BR capabilities (7)
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.PP
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.BR sched_setscheduler (2)
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has a description of the Linux scheduling scheme.
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.PP
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.I Programming for the real world \- POSIX.4
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by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0
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.br
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.I IEEE Std 1003.1b-1993
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(POSIX.1b standard)
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.br
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.I ISO/IEC 9945-1:1996
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