.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" Copyright (C) Tom Bjorkholm, Markus Kuhn & David A. Wheeler 1996-1999
.\" and Copyright (C) 2007 Carsten Emde <Carsten.Emde@osadl.org>
.\" and Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
.\" the License, or (at your option) any later version.
.\"
.\" The GNU General Public License's references to "object code"
.\" and "executables" are to be interpreted as the output of any
.\" document formatting or typesetting system, including
.\" intermediate and printed output.
.\"
.\" This manual is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public
.\" License along with this manual; if not, write to the Free
.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
.\" USA.
.\"
.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>
.\"            First version written
.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
.\"            revision
.\" 1999-08-18 David A. Wheeler <dwheeler@ida.org> added Note.
.\" Modified, 25 Jun 2002, Michael Kerrisk <mtk.manpages@gmail.com>
.\"	Corrected description of queue placement by sched_setparam() and
.\"		sched_setscheduler()
.\"	A couple of grammar clean-ups
.\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>
.\" 2005-03-23, mtk, Added description of SCHED_BATCH.
.\" 2007-07-10, Carsten Emde <Carsten.Emde@osadl.org>
.\"     Add text on real-time features that are currently being
.\"     added to the mainline kernel.
.\" 2008-05-07, mtk; Rewrote and restructured various parts of the page to
.\"     improve readability.
.\"
.\" Worth looking at: http://rt.wiki.kernel.org/index.php
.\"
.\" Japanese Version Copyright (c) 1996 Akira Yoshiyama
.\"         all rights reserved.
.\" Translated Thu Jul 11 01:42:52 JST 1996
.\"         by Akira Yoshiyama <yosshy@jedi.seg.kobe-u.ac.jp>
.\" Modified Sun Nov 21 19:36:18 JST 1999
.\"         by HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated Wed Jan  1 JST 2003 by Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2005-02-24, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated & Modified 2005-10-10, Akihiro MOTOKI
.\" Updated 2006-04-16, Akihiro MOTOKI, Catch up to LDP v2.28
.\" Updated 2007-10-13, Akihiro MOTOKI, LDP v2.65
.\" Updated 2008-08-13, Akihiro MOTOKI, LDP v3.05
.\"
.\"WORD:	privileges		ø
.\"WORD:	resource limit		꥽
.\"WORD:	scheduling policy	塼󥰡ݥꥷ
.\"
.TH SCHED_SETSCHEDULER 2 2008-11-06 "Linux" "Linux Programmer's Manual"
.SH ̾
sched_setscheduler, sched_getscheduler \-
塼󥰡ݥꥷȥѥ᡼/
.SH 
.nf
.B #include <sched.h>
.sp
.BI "int sched_setscheduler(pid_t " pid ", int " policy ,
.br
.BI "                       const struct sched_param *" param );
.sp
.BI "int sched_getscheduler(pid_t " pid );
.sp
\fBstruct sched_param {
    ...
    int \fIsched_priority\fB;
    ...
};
.fi
.SH 
.BR sched_setscheduler ()
 \fIpid\fP ǻꤵ줿 ID ĥץΥ塼󥰡ݥꥷ
˴Ϣѥ᡼ꤹ롣\fIpid\fP  0 ξ
ƤӽФץΥ塼󥰡ݥꥷȥѥ᡼ꤵ롣
 \fIparam\fP β򤵤줿ݥꥷˤ롣
ߤΤȤLinux Ǥ
ʲ˼̾(ꥢ륿Ǥʤ) 塼󥰡ݥꥷ
ݡȤƤ롣
.TP 14
.BR SCHED_OTHER
ɸΡ饦ɥӥˤʬ䷿Υ塼󥰡ݥꥷ
.\" 2.6 ͥ륽ǤϡSCHED_OTHER ϼºݤˤ
.\" SCHED_NORMAL ȸƤФƤ롣
.TP
.BR SCHED_BATCH
֥Хå׷ǤΥץμ¹ѡ
.TP
.BR SCHED_IDLE
ˡ㤤ͥ٤ưХå饦ɡѡ
.PP
ɤμ¹Բǽץ򤹤뤫ˤĤơΤɬפȤ
֤󤬸̤ʥץꥱѤȤơ
ʲΡ֥ꥢ륿ץݥꥷ⥵ݡȤƤ롣
.TP 14
.BR SCHED_FIFO
եȥ󡢥եȥȷΥݥꥷ
.TP
.BR SCHED_RR
饦ɥӥ󷿤Υݥꥷ
.PP
ΥݥꥷΤ줾ưˤĤƤϰʲ롣

.BR sched_getscheduler ()
 \fIpid\fP Ǽ̤ץ˸ŬѤƤ
塼󥰡ݥꥷҤͤ롣\fIpid\fP  0 ʤСƤӽФ
ץȤΥ塼󥰡ݥꥷ֤롣
.\"
.SS 塼󥰡ݥꥷ (scheduling policy)
塼 (scheduler) ȤϥͥιǤǡ
 CPU Ǽ¹Ԥ¹ԲǽʥץꤹΤǤ롣
ơΥץˤϡ塼󥰡ݥꥷ
Ūפʥ塼ͥ \fIsched_priority\fP бդ졢

.BR sched_setscheduler ()
ѹǤ롣
塼ϡƥץΥ塼󥰡ݥꥷ
Ūͥ٤˴ؤμ˴ŤƷԤ

̾Υ塼󥰡ݥꥷ
(\fBSCHED_OTHER\fP, \fBSCHED_IDLE\fP, \fBSCHED_BATCH\fP)
βǥ塼󥰤ץǤϡ
\fIsched_priority\fP ϥ塼󥰤η˻Ѥʤ
(\fIsched_priority\fP ˤ 0 ꤷʤФʤʤ)

ꥢ륿ࡦ塼󥰡ݥꥷ (\fBSCHED_FIFO\fP, \fBSCHED_RR\fP)
βǥ塼󥰤ץϡ
\fIsched_priority\fP ͤ 1 ()  99 (ǹ) ϰϤȤʤ
(ʬ褦ˡꥢ륿ࡦץϾ̾Υץ
⤤ͥ٤)
դ٤ʤΤϡPOSIX.1-2001 ׵ᤷƤΤϡ
ꥢ륿ࡦݥꥷμˤƺ 32 ΰۤʤͥ٥٥뤬
ݡȤ뤳ȤǤꡢĤΥƥǤϤκ¤ο
ͥ٤󶡤ƤʤȤȤǤ롣
ܿɬפʥץǤϡ
.BR sched_get_priority_min (2)

.BR sched_get_priority_max (2)
ȤäơݥꥷݡȤͥ٤ϰϤĴ٤٤Ǥ롣

ǰȤƤϡ
塼Ϥ \fIsched_priority\fP ͤ줾Ф
¹ԲǽʥץΥꥹȤƤ롣
ɤΥץ򼡤˼¹Ԥ뤫ꤹ뤿ˡ
塼Ūͥ٤κǤ⤤ǤʤꥹȤõơ
ΥꥹȤƬΥץ򤹤롣

ƥץΥ塼󥰡ݥꥷϡ
ΥץƱŪͥ٤ĥץΥꥹȤΤɤ졢
ΥꥹȤɤΤ褦˰ư뤫ꤹ롣

ƤΥ塼󥰤ϥץꥨץƥ (preemptive) Ǥ:
⤤ͥ٤Υץ¹Բǽˤʤȡ߼¹Υץϼ¹Ը
夲 (preempted)ΥץŪͥ٥٥ԤꥹȤ
ᤵ롣塼󥰡ݥꥷƱŪͥ٤ļ¹Բǽ
ץΥꥹȤǽ֤Τߤꤹ롣
.SS SCHED_FIFO: եȥ󡦥եȥȡ塼
\fBSCHED_FIFO\fP  0 礭Ūͥ٤ǤΤ߻ѤǤ롣ΥݥꥷǤϡ
\fBSCHED_FIFO\fP ץ¹Բǽˤʤä硢
Υݥꥷ \fBSCHED_OTHER\fP \fBSCHED_BATCH\fP \fBSCHED_IDLE\fP 
߼¹Υץľ˼¹Ը夲롣
\fBSCHED_FIFO\fP ϻʬΤʤñʥ塼󥰡르ꥺǤ롣
\fBSCHED_FIFO\fP ݥꥷǥ塼󥰤Ƥץˤϰʲ
롼뤬ŬѤ:
.IP * 3
⤤ͥ٤¾ΥץˤäƼä줿
\fBSCHED_FIFO\fP ץϤͥ٤ΥꥹȤƬαޤ³
⤤ͥ٤ΥץƤ (block) ˼¹ԤƳ롣
.IP *
\fBSCHED_FIFO\fP ץ¹Բǽˤʤäͥ٤ΥꥹȤκǸ
롣
.IP *
.BR sched_setscheduler ()

.BR sched_setparam (2)

\fIpid\fP ǻꤵ줿 \fBSCHED_FIFO\fP (ޤ \fBSCHED_RR\fP) ץ
¹Բǽʾ硢ꥹȤκǽ֤
̤Ȥơ⤷ͥ٤Ʊä硢
߼¹Υץ󤸤뤫⤷ʤ
(POSIX.1-2001 ǤϥץϥꥹȤκǸ˹Ԥ٤ȵꤵƤ롣)
.\" In 2.2.x and 2.4.x, the process is placed at the front of the queue
.\" In 2.0.x, the Right Thing happened: the process went to the back -- MTK
.IP *
.BR sched_yield (2)
ƤӽФץϥꥹȤκǸ֤롣
.PP
¾Υ٥Ȥˤä \fBSCHED_FIFO\fP ݥꥷ
塼󥰤ץƱͥ٤μ¹Բǽ
ץԤꥹȤư뤳ȤϤʤ

\fBSCHED_FIFO\fP ץ I/O ׵ˤäߤ뤫
⤤ͥ٤Υץˤä֤뤫
.BR sched_yield (2)
ƤӽФޤǼ¹Ԥ³롣
.SS SCHED_RR: 饦ɡӥ (round robin) 塼
\fBSCHED_RR\fP  \fBSCHED_FIFO\fP ñʳĥǤ롣
Ҥ줿 \fBSCHED_FIFO\fP ˴ؤ뵭Ҥ \fBSCHED_RR\fP 
ŬѤǤ롣ۤʤΤϤ줾ΥץϺñ̤ޤǤ¹ԤǤʤ
ȤȤǤ롣\fBSCHED_RR\fP ץñ̤Ʊ
Ĺּ¹Ԥȡͥ٤ΥꥹȤκǸ֤롣
⤤ͥ٤Υץˤä֤졢θ¹ԤƳ
\fBSCHED_RR\fP ץϡΥ饦ɡӥñ̤˻Ȥڤ
ޤǼ¹Ԥ롣λñ̤Ĺ
.BR sched_rr_get_interval (2)
ȤäƼǤ롣
.\" On Linux 2.4, the length of the RR interval is influenced
.\" by the process nice value -- MTK
.\"
.SS SCHED_OTHER: Linux ΥǥեȤλʬ䥹塼
\fBSCHED_OTHER\fP Ūͥ 0 ǤΤ߻ѤǤ롣
\fBSCHED_OTHER\fP  Linux ɸλʬ䥹塼ǡ
̤ʥꥢ륿ൡɬפȤƤʤƤΥץǻѤ롣
¹ԤץϡŪͥ 0 ΥꥹȤ顢ΥꥹȤ
ꤵưŪʡͥ (dynamic priority) ˴𤤤Ʒꤵ롣
ưŪͥ٤
.RB ( nice (2)

.BR setpriority (2)
ˤꤵ) nice ͤ˴ŤƷꤵΤǡ
ñ̻ˡץ¹Բǽ塼ˤ¹Ԥݤ줿
˥󥯥Ȥ롣
ˤꡢƤ \fBSCHED_OTHER\fP ץǤθʿݾڤ롣
.\"
.SS SCHED_BATCH: ХåץΥ塼
(Linux 2.6.16 ʹ)
\fBSCHED_BATCH\fP Ūͥ 0 ǤΤ߻ѤǤ롣
Υݥꥷ (nice ͤ˴Ť) ưŪͥ٤ˤäƥץ
塼󥰤ԤȤǡ\fBSCHED_OTHER\fP ˻Ƥ롣
ۤʤΤϡΥݥꥷǤϡץ CPU ٤Τ (CPU-intensive)
Ԥȡ塼餬ꤹǤ롣
塼ϥץƤӵˤΥץ˥塼󥰾
ڥʥƥ򾯤ݤη̡Υץϥ塼󥰤η
㴳褦ˤʤ롣

.\" The following paragraph is drawn largely from the text that
.\" accompanied Ingo Molnar's patch for the implementation of
.\" SCHED_BATCH.
ΥݥꥷϡŪʽ nice ͤ򲼤ʤ䡢
(Υ֤) ;פʥ֤θȤŪʽʤ
Ū (deterministic) 塼󥰡ݥꥷŬѤ
ФͭǤ롣
.\"
.SS SCHED_IDLE: ͥ٤㤤֤Υ塼
(Linux 2.6.23 ʹ)
\fBSCHED_IDLE\fP Ūͥ 0 ǤΤ߻ѤǤ롣
ΥݥꥷǤϥץ nice ͤϥ塼󥰤˱ƶͿʤ

㤤ͥ٤ǤΥ֤μ¹ԤŪȤΤǤ
(㤤ͥ٤Ȥϡݥꥷ
.B SCHED_OTHER

.B SCHED_BATCH
Ǥ nice  +19 ꤵ㤤ͥ٤Ǥ)
.\"
.SS øȥ꥽
2.6.12 ΥС Linux ͥǤϡ
øץ
.RB ( CAP_SYS_NICE
ѥӥƥĥץ)  0 ʳŪͥ٤ꤹ
(ʤꥢ륿ࡦ塼󥰡ݥꥷꤹ) ȤǤ롣
øץǤѹ
.B SCHED_OTHER
ݥꥷꤹ뤳ȤǤꡢˤѹԤΤ
.BR sched_setscheduler ()
θƤӽФμ¸桼 ID ݥꥷѹоݥץ
.RI ( pid
ǻꤵ줿ץ) μ¥桼 ID ¸桼 ID 
פǤ롣

Linux 2.6.12 ʹߤǤϡ꥽
.B RLIMIT_RTPRIO
Ƥꡢ
塼󥰡ݥꥷ
.B SCHED_RR

.B SCHED_FIFO
ξΡøץŪͥ٤ξ¤Ƥ롣
塼󥰡ݥꥷͥ٤ѹݤΥ롼ϰʲ̤Ǥ롣
.IP * 2
øץ 0 ʳ
.B RLIMIT_RTPRIO
եȡߥåȤꤵƤ硢
øץϤΥץΥ塼󥰡ݥꥷͥ٤
ѹǤ뤬ͥ٤򸽺ߤμȤͥ٤
.B RLIMIT_RTPRIO
եȡߥåȤ礭⤤ͤǤʤȤ¤ݤ롣
.IP *
.B RLIMIT_RTPRIO
եȡߥåȤ 0 ξ硢ͥ٤򲼤뤫
ꥢ륿Ǥʤݥꥷڤؤ뤫ѹĤ롣
.IP *
øץ̤ΥץФƤѹԤݤˤ⡢
Ʊ롼뤬ŬѤ롣ѹԤΤϡѹԤȤץ
μ¸桼 ID ѹоݤΥץμ¥桼 ID ¸桼 ID 
פƤ˸¤롣
.IP *
.B SCHED_IDLE
ˤ̤ʥ롼뤬ŬѤ졢
Υݥꥷβưøץϡ꥽
.B RLIMIT_RTPRIO
ͤˤ餺ȤΥݥꥷѹ뤳ȤǤʤ
.PP
øץ
.RB ( CAP_SYS_NICE
ѥӥƥĥץ) ξ硢
.B RLIMIT_RTPRIO
¤̵뤵;
ŤͥƱ褦ˡ塼󥰡ݥꥷͥ٤Ф
ǤդѹԤȤǤ롣
.B RLIMIT_RTPRIO
˴ؤäȾܤ
.BR getrlimit (2)
򻲾ȤΤȡ
.SS  (response time)
I/O Ԥߤ⤤ͥ٤ΥץϺƤӥ塼󥰤
ˤ餫α֤롣ǥХɥ饤С񤯾ˤ
.\" .BR request_irq (9)
.\" ˵ҤƤ
"slow interrupt" ߥϥɥ顼Ѥ뤳Ȥ
α֤Ū˸뤳ȤǤ롣
.SS ¾
ҥץ
.BR fork (2)
κݤ˿ƥץΥ塼󥰡ݥꥷȥѥ᡼Ѿ롣
.BR execve (2)
ǡ塼󥰡ݥꥷȥѥ᡼ݻ롣

ꥢ륿ࡦץ񡢥ڡ󥰤Ԥ֤򤱤뤿
.BR mlock (2)

.BR mlockall (2)
Ȥäƥꡦå򤷤ʤФʤʤ

\fBSCHED_FIFO\fP  \fBSCHED_RR\fP ǥ塼󥰤
ץߤ̵¥롼פ˴٤ȡ
¾ƤΤ㤤ͥ٤Υץʵפ (block) ƤޤΤǡ
եȥȯԤϥ󥽡ΥŪͥ٤ƥȤ
ץꥱ˹⤯ݤĤ٤Ǥ롣
ˤäƴ̤ߤ꽪λꤷʤꥢ륿ࡦ
ץꥱ۵޽λ뤳Ȥǽˤʤ롣
.BR getrlimit (2)
Υ꥽
.B RLIMIT_RTTIME
⻲ȤΤȡ

POSIX ƥǤ \fI<unistd.h>\fP 
.B _POSIX_PRIORITY_SCHEDULING
ƤˤΤ
.BR sched_setscheduler ()

.BR sched_getscheduler ()
ѤǤ롣
.SH ֤
硢
.BR sched_setscheduler ()
 0 ֤
硢
.BR sched_getscheduler ()
ϸߤΤΥץΥݥꥷ () ֤
顼ξ硢\-1 ֤졢
.I errno
Ŭڤꤵ롣
.SH 顼
.TP
.B EINVAL
塼󥰡ݥꥷ \fIpolicy\fP ְäƤ뤫
\fIparam\fP ΥݥꥷǤϰ̣ʤʤ
.TP
.B EPERM
ƤӽФץŬڤøäƤʤ
.TP
.B ESRCH
ID \fIpid\fP ΥץĤʤ
.SH 
POSIX.1-2001 (âΥХ⻲)
\fBSCHED_BATCH\fP  \fBSCHED_IDLE\fP ݥꥷ Linux ͭǤ롣
.SH 
POSIX.1 ϡøץ
.BR sched_setscheduler ()
ƤӽФɬפʸ¤ξܺ٤ꤷƤ餺
ܺ٤ϥƥˤۤʤ롣
㤨СSolaris 7 Υޥ˥奢ڡǤϡ
ƤӽФץμ¥桼 ID ޤϼ¸桼 ID 
оݤΥץμ¥桼 ID ¸ (save) set-user-ID 
פƤʤФʤʤȤʤäƤ롣
.PP
ȤȤϡɸ Linux ϰŪΥڥ졼ƥ󥰥ƥȤ
߷פƤꡢХå饦ɡץŪץꥱ
ꥢ륿׵᤬ʤꥢ륿ࡦץꥱ
(̤ϥߥ󥰤α (deadline) ɬפ륢ץꥱ)
򰷤ȤǤ
Linux ͥ 2.6 Ǥϡ
ͥΥץꥨץ (֤) ǽǤꡢ
Ƴ줿 O(1) 塼ˤꡢ
ƥ֤ʥο˴ؤ餺塼󥰤ɬפʻ֤
dzŪ (deterministic) Ǥ뤳ȤݾڤƤ롣
ˤؤ餺ͥ 2.6.17 ޤǤ
Υꥢ륿ࡦԥ塼ƥ󥰤ϼ¸Ǥʤä
.SS ή Linux ͥǤΥꥢ륿ൡǽ
.\" FIXME . Probably this text will need some minor tweaking
.\" by about the time of 2.6.30; ask Carsten Emde about this then.
ͥ 2.6.18 鸽ߤޤǡ
Linux Ͻ˥ꥢ륿ൡǽĤĤ뤬
εǽΤۤȤɤϡ
Ingo Molnar, Thomas Gleixner, Steven Rostedt ˤäƳȯ줿

.I realtime-preempt
ѥåΤΤǤ롣
ΥѥåήΥͥ˴˥ޡޤǤ
(ޡδλϥͥ 2.6.30 ͽ)
ǹΥꥢ륿ǽãˤ realtime-preempt ѥå
Ȥ߹ޤʤФʤʤ
Υѥå
.in +4n
.nf

patch-\fIkernelversion\fP-rt\fIpatchversion\fP
.fi
.in
Ȥ̾ǡ
.I http://www.kernel.org/pub/linux/kernel/projects/rt/
ɤǤ롣

ΥѥåŬѤ줺ĥѥåƤήΥͥؤΥޡ
λޤǤϡͥǤ
.BR CONFIG_PREEMPT_NONE ,
.BR CONFIG_PREEMPT_VOLUNTARY ,
.B CONFIG_PREEMPT_DESKTOP
 3ĤΥץꥨץ󡦥饹 (preemption class) 󶡤롣
Υ饹ǤϡǰξΥ塼ٱ䤬줾
ʤ餫롢ʤ긺롣

ѥåŬѤ줿硢ޤϥѥåƤήΥͥؤΥޡ
λǤϡ嵭˲äܤȤ
.B CONFIG_PREEMPT_RT
Ѳǽˤʤ롣ιܤ򤹤ȡ
Linux ̾Υꥢ륿ࡦڥ졼ƥ󥰥ƥѿȤ롣
ξˤϡ
.BR sched_setscheduler ()
Ǥ FIFO  RR Υ塼󥰡ݥꥷϡ
Υꥢ륿ͥ٤ĥץǰξΥ塼ٱ䤬
ǾȤʤĶư뤿˻Ȥ뤳Ȥˤʤ롣
.SH Х
POSIX Ǥϡ
.BR sched_setscheduler ()
ľΥ塼󥰡ݥꥷ֤٤ȤƤ롣
Linux 
.BR sched_setscheduler ()
Ϥ׵ͤ˽򤷤Ƥ餺
ˤϾ 0 ֤
.SH Ϣ
.BR getpriority (2),
.BR mlock (2),
.BR mlockall (2),
.BR munlock (2),
.BR munlockall (2),
.BR nice (2),
.BR sched_get_priority_max (2),
.BR sched_get_priority_min (2),
.BR sched_getaffinity (2),
.BR sched_getparam (2),
.BR sched_rr_get_interval (2),
.BR sched_setaffinity (2),
.BR sched_setparam (2),
.BR sched_yield (2),
.BR setpriority (2),
.BR capabilities (7),
.BR cpuset (7)
.PP
.I Programming for the real world \- POSIX.4
by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0
.PP
ͥ롦Υե
.I Documentation/scheduler/sched-rt-group.txt
(ͥ 2.6.25 ʹ)