.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" Copyright (C) Tom Bjorkholm, Markus Kuhn & David A. Wheeler 1996-1999
.\"
.\" 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.
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.\" 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@gmx.net>
.\"	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@gmx.net>
.\" 2005-03-23, mtk, Added description of SCHED_BATCH.
.\"
.\" 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
.\"
.\"WORD:	privileges		ø
.\"
.TH SETSCHEDULER 2 2006-03-23 "Linux 2.6.16" "Linux Programmer's Manual"
.SH ̾
sched_setscheduler, sched_getscheduler \-
塼󥰡르ꥺȥѥ᡼/
.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 ˤäƼ̤ץΥ塼ˤ
˴Ϣѥ᡼ꤹ롣\fIpid\fP  0 ξ
ƤӽФץΥ塼󥰤ꤵ롣
ѥ᡼ \fIparam\fP β򤵤줿ˤˤ롣
ߤΤȤLinux Ǥ
.IR SCHED_FIFO , 
.IR SCHED_RR ,
.IR SCHED_OTHER ,
.\" 2.6 ͥ륽ǤϡSCHED_OTHER ϼºݤˤ
.\" SCHED_NORMAL ȸƤФƤ롣
.I SCHED_BATCH
Υ塼ˤݡȤƤ롣
줾ˤĤƤϰʲǽҤ٤롣

.BR sched_getscheduler ()
 \fIpid\fP Ǽ̤ץ˸ŬѤƤ
塼ˤҤͤ롣\fIpid\fP  0 ʤСƤӽФ
ץȤΥ塼ˤ֤롣
.SS 塼 (scheduling policy)
塼 (scheduler) Ȥϥͥΰǡ CPU Ǽ¹Ԥ
¹ԲǽʥץꤹΤǤ롣
Linux Υ塼顼ϻĤΰۤʤ륹塼ˤ󶡤Ƥꡢ
Ĥ̾ΥץѡĤϥꥢ륿ࡦץꥱѤǤ롣
ƤΥץˤ
Ūͥ (static priority) \fIsched_priority\fP Ƥ졢
ͤϥƥࡦ̤ƤΤѹǤ롣
\fIsched_priority\fP  0  99 ϰϤͤ뤳ȤǤ
塼Ϥ \fIsched_priority\fP ͤ줾Ф
¹ԲǽʥץΥꥹȤƤ롣˼¹Ԥץ
ꤹ뤿ˡLinux Υ塼Ūͥ٤κǤ⤤
ǤʤꥹȤõơΥꥹȤƬΥץФ
塼ˤϤ줾ΥץƱŪͥ٤
ץΥꥹȤΤɤ졢ΥꥹȤɤΤ褦
ư뤫ꤹ롣

\fISCHED_OTHER\fP ϥǥեȤΰŪʻʬ䷿塼ˤǡ
¿ΥץˤäƻѤ롣
\fISCHED_BATCH\fP ϥץΡ֥Хåץפμ¹ԤŪ
ΤǤ롣 
\fISCHED_FIFO\fP \fISCHED_RR\fP Ϥɤμ¹Բǽץ򤹤뤫
ˤĤơΤɬפȤ֤󤬸ü
ץꥱΤΤΤǤ롣

\fISCHED_OTHER\fP  \fISCHED_BATCH\fP ǥ塼󥰤Ƥ
ץŪͥ٤Ȥ 0 ꤵʤФʤʤ
\fISCHED_FIFO\fP  \fISCHED_RR\fP
ǥ塼󥰤Ƥץ 1  99 ϰϤ
Ūͥ٤뤳ȤǤ롣
\fBsched_get_priority_min\fP()  \fBsched_get_priority_max\fP()
ƥࡦѤ뤳ȤƤ POSIX.1-2001 ߴƥ
ܿǽˡͭͥ٤ϰϤ뤳ȤǤ롣

ƤΥ塼󥰤ϥץꥨץƥ (preemptive) Ǥ: 
⤤ͥ٤Υץμ¹ԤνǤȡߤΥץ
ͥŪʤΤ֤ (preempted)ԤꥹȤᤵ롣
塼ˤƱŪͥ٤ļ¹Բǽʥץ
ꥹȤǽ֤Τߤꤹ롣
.SS SCHED_FIFO: եȥ󡦥եȥȡ塼
\fISCHED_FIFO\fP  0 礭Ūͥ٤ǤΤ߻ѤǤ
\fISCHED_FIFO\fP ץ¹Բǽˤʤä硢ˡ߼¹ԤƤ
\fISCHED_OTHER\fP  \fISCHED_BATCH\fP ץ֤롣
\fISCHED_FIFO\fP ϻʬΤʤñʥ塼󥰡르ꥺǤ롣
\fISCHED_FIFO\fP ˤǥ塼󥰤Ƥץˤϰʲ
§ŬѤ: ⤤ͥ٤¾Υץˤä֤줿
\fISCHED_FIFO\fP ץϤͥ٤ΥꥹȤƬαޤ³
⤤ͥ٤ΥץƤ (block) ˤϺƤӼ¹Ԥ³롣
\fISCHED_FIFO\fP ץ¹Բǽˤʤäͥ٤ΥꥹȤκǸ
롣\fBsched_setscheduler\fP()  \fBsched_setparam\fP() 
\fIpid\fP ǻꤵ줿 \fISCHED_FIFO\fP (ޤ \fISCHED_RR\fP) ץ
¹Բǽʾ硢ꥹȤκǽ֤
̤Ȥơ⤷ץ饤ƥƱä硢
߼¹Υץ󤸤뤫⤷ʤ
(POSIX.1-2001 ǤϥץϥꥹȤκǸ˹Ԥ٤ȵꤵƤ롣)
\fBsched_yield\fP() ƤӽФץϥꥹȤ
Ǹ֤롣¾Υ٥Ȥˤä \fISCHED_FIFO\fP ˤ
塼󥰤ץƱͥ٤μ¹Բǽʥץ
ԤꥹȤư뤳ȤϤʤ\fISCHED_FIFO\fP ץ
I/O ׵ˤäߤ뤫⤤ͥ٤Υץˤä֤
뤫\fBsched_yield\fP() ƤӽФޤǼ¹Ԥ³롣
.SS SCHED_RR: 饦ɡӥ (round robin) 塼
\fISCHED_RR\fP  \fISCHED_FIFO\fP ñʳĥǤ롣
Ҥ줿 \fISCHED_FIFO\fP ˴ؤ뵭Ҥ \fISCHED_RR\fP 
ŬѤǤ롣ۤʤΤϤ줾ΥץϺñ̤ޤǤ¹ԤǤʤ
ȤȤǤ롣\fISCHED_RR\fP ץñ̤Ʊ
Ĺּ¹Ԥȡͥ٤ΥꥹȤκǸ֤롣
⤤ͥ٤Υץˤä֤졢θ¹ԤƳ
\fISCHED_RR\fP ץϡΥ饦ɡӥñ̤˻Ȥڤ
ޤǼ¹Ԥ롣λñ̤Ĺ \fBsched_rr_get_interval\fP(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
\fISCHED_OTHER\fP Ūͥ 0 ǤΤ߻ѤǤ롣
\fISCHED_OTHER\fP  Linux ɸλʬ䥹塼ǡ
üŪͥ٤ꥢ롦ൡɬפȤƤʤƤ
ץǻѤ롣¹ԤץŪͥ 0 ΥꥹȤ
Τߤ顢ưŪͥ (dynamic priority) ˴𤤤Ʒꤵ롣
ưŪͥ٤ (\fBnice\fP(2)  \fBsetpriority\fP(2) ˤäꤵ)
nice ٥˴ŤƤ롣ͤϥץμ¹ԽǤƤꡢ
塼ˤäƼ¹ԤݤƤ֡ñ̤Ȥ˥󥯥
롣Ƥ \fISCHED_OTHER\fP ץ˸ʿǤ뤳Ȥݾڤ롣
.SS SCHED_BATCH: ХåץΥ塼
(Linux 2.6.16 ʹ)
\fISCHED_BATCH\fP Ūͥ 0 ǤΤ߻ѤǤ롣
ˤ \fISCHED_OTHER\fP ȻƤ뤬ˤǤϥ塼餬
ץ CPU ٤Τ (CPU-intensive) ԤȲꤹ
ۤʤ롣̤Ȥơ塼ϤΥץ˥塼󥰾
Υڥʥƥ򾯤ݤΥץϥ塼󥰤ηǼ㴳
褦ˤʤ롣
.\" The following paragraph is drawn largely from the text that 
.\" accompanied Ingo Molnar's patch for the implementation of 
.\" SCHED_BATCH.
ˤϡŪʽ nice ͤ򲼤ʤ䡢
(Υ֤) ;פʥ֤θȤŪʽʤ
Ū (deterministic) 塼ˤŬѤ
ФͭǤ롣
.SS øȥ꥽
.\" FIXME make some general statement about Unix implementations
.\" .B sched_setscheduler
.\" ƤӽФץϡμ¸桼 ID 
.\" .I pid
.\" ǻꤵ줿ץμ¥桼 ID ¸桼 ID ȰפƤ뤫
.\" ⤷ø
.\" .RB ( CAP_SYS_NICE
.\" ѥӥƥ) äƤʤФʤʤ
2.6.12 ΥС Linux ͥǤϡ
øץ
.RB ( CAP_SYS_NICE
ѥӥƥĥץ) 
0 ʳŪͥ٤ꤹ뤳ȤǤ롣
øץǤѹ
.B SCHED_OTHER
ˤꤹ뤳ȤǤꡢˤѹԤΤ
.BR sched_setscheduler ()
θƤӽФμ¸桼 ID ˤѹоݥץ
.RI ( pid
ǻꤵ줿ץ) μ¥桼 ID ¸桼 ID 
פǤ롣

Linux 2.6.12 ʹߤǤϡ꥽
.B RLIMIT_RTPRIO
Ƥꡢ
塼ˤ
.B SCHED_RR

.B SCHED_FIFO
ξΡøץͥ٤ξ¤Ƥ롣
øץ 0 ʳ
.B RLIMIT_RTPRIO
եȡߥåȤꤵƤ硢
øץϤΥץΥ塼󥰤ˤͥ٤
ѹǤ뤬ͥ٤
.B RLIMIT_RTPRIO
եȡߥåȤ⤤ͤǤʤȤ¤ݤ롣
.B RLIMIT_RTPRIO
եȡߥåȤ 0 ξ硢ͥ٤򲼤ѹĤʤ
øץ̤ΥץФƤѹԤݤˤ⡢
Ʊ롼뤬ŬѤ롣ѹԤΤϡѹԤȤץ
μ¸桼 ID ѹоݤΥץμ¥桼 ID ¸桼 ID 
פƤ˸¤롣
.B RLIMIT_RTPRIO
˴ؤäȾܤ
.BR getrlimit (2)
򻲾ȤΤȡ
øץ
.RB ( CAP_SYS_NICE
ѥӥƥĥץ) ξ硢¤̵뤵;
ŤͥƱ褦ˡ塼ˤͥ٤Ф
ǤդѹԤȤǤ롣
.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 ()
κݤ˿ƥץΥ塼󥰡르ꥺѾ롣
.BR execve (2)
ǡ塼󥰡르ꥺȥѥ᡼ݻ롣

ꥢ롦ࡦץ񡢥ڡ󥰤Ԥ֤򤱤뤿
.BR mlock ()

.BR mlockall ()
Ȥäƥꡦå򤷤ʤФʤʤ

\fISCHED_FIFO\fP  \fISCHED_RR\fP ǥ塼󥰤
ץߤ̵¥롼פˤȡ
¾ƤΤ㤤ͥ٤Υץʵפ (block) ƤޤΤǡ
եȥȯԤϥ󥽡ΥŪͥ٤ƥȤ
ץꥱ˹⤯ݤĤ٤Ǥ롣
ˤäƴ̤ߤ꽪λꤷʤꥢ롦ࡦ
ץꥱ۵޽λ뤳Ȥǽˤʤ롣

POSIX ƥǤ <unistd.h> 
.I _POSIX_PRIORITY_SCHEDULING
ƤˤΤ
.BR sched_setscheduler ()

.BR sched_getscheduler ()
ѤǤ롣
.SH ֤
硢
.BR sched_setscheduler ()
 0 ֤
硢
.BR sched_getscheduler ()
ϸߤΤΥץ () ֤
顼ξ硢\-1 ֤졢
.I errno
Ŭڤꤵ롣
.SH 顼
.TP
.B EINVAL
塼 \fIpolicy\fP ְäƤ뤫
ѥ᡼ \fIparam\fP ˤǤϰ̣ʤʤ
.TP
.B EPERM
ƤӽФץŬڤøäƤʤ
.TP
.B ESRCH
ID \fIpid\fP ΥץĤʤ
.SH 
POSIX.1-2001.
\fISCHED_BATCH\fP ˤ Linux ͭǤ롣
.SH 
ɸŪ Linux ϰŪΥڥ졼ƥ󥰥ƥʤΤǡ
Хå饦ɡץ䡢Ūץꥱ
եȡꥢ륿(soft real-time)ץꥱ
(̤Υߥ󥰤α (deadline) ɬפʥץꥱ) 򰷤롣
.PP
ɸŪ Linux  (Ф 1ðʲ) ¤ݾڤɬפäꡢ
ԤŪʻ֤ϡɡꥢ륿 (hard real-time)
ץꥱ򥵥ݡȤ褦ˤ
.I ߷פƤʤ
¾ƤΰŪΥڥ졼ƥ󥰥ƥƱͤ Linux 
ǰΥѥեޥ󥹤ǤϤʤ
ʿŪʥѥեޥ󥹤粽褦˥ǥ󤵤Ƥ롣
Linux κǰξγ߽ʿŪʾ٤礭äƤ롣
(SMP ΤΥåΤ褦) ޤޤʥͥåĹĹԤ
ޤʿѻ֤򸺤餹˳ȯ줿¿Υѥեޥ
ɵѤˤäƺǰλ֤ä롣
¿ξǤϤ줬ʤ˾ư⤷
ϡɡꥢ륿ࡦץꥱȯƤˤ
RTLinux (http://www.rtlinux.org)  RTAI (http://www.rtai.org)
Τ褦ʥꥢ륿ĥ줿
Linux 丷ꥢ롦ॢץꥱѤ߷פ줿
¾ OS λѤθ٤Ǥ롣
.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)
.PP
.I Programming for the real world \- POSIX.4
by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0