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.\" 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
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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.
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.\" 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.
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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
.\" 1999-08-18 David A. Wheeler <dwheeler@ida.org> added Note.
.\"
.\" 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>
.\"
.TH SETSCHEDULER 2 "1999-08-18" "Linux 2.2.11" "Linux Programmer's Manual"
.SH ̾
sched_setscheduler, sched_getscheduler \-
塼󥰡르ꥺȥѥ᡼/
.SH 
.B #include <sched.h>
.sp
\fBint sched_setscheduler(pid_t \fIpid\fB, int \fIpolicy\fB, 
const struct sched_param *\fIp\fB);
.sp
\fBint sched_getscheduler(pid_t \fIpid\fB);
.sp
.nf
.ta 4n
\fBstruct sched_param {
	...
	int \fIsched_priority\fB;
	...
};
.ta
.fi
.SH 
.B sched_setscheduler
 \fIpid\fR ˤäƼ̤ץΥ塼ˤ
˴Ϣѥ᡼ꤹ롣\fIpid\fR ξ
ƤӽФץΥ塼󥰤ꤵ롣
ѥ᡼ \fIp\fR β򤵤줿ˤˤ롣ߡLinux Ǥ
ʲ3ĤΥ塼ˤݡȤƤ:
.IR SCHED_FIFO , 
.IR SCHED_RR ,
.IR SCHED_OTHER ;
줾ˤĤƤϰʲǽҤ٤롣

.B sched_getscheduler
 \fIpid\fR Ǽ̤ץ˸ŬѤƤ
塼ˤҤͤ롣\fIpid\fR ʤСƤӽФ
ץȤΥ塼ˤ֤롣

.SS 塼(scheduling policy)
塼顼(scheduler)Ȥϥͥΰǡ CPU Ǽ¹Ԥ
¹Բǽʥץꤹ롣Linux Υ塼顼ϻĤΰۤä
塼ˤ󶡤ƤꡢĤ̾ΥץΤ
Ĥϥꥢ륿(real-time)ץꥱΤ˻Ȥ롣
Ūͥ(static priority) \fIsched_priority\fR 
ƤΥץ˻ꤵ졢ͤϥƥࡦ̤ƤΤѹǤ롣
\fIsched_priority\fR  0  99 ϰϤͤ뤳ȤǤ
塼顼Ϥ \fIsched_priority\fR ͤ줾Ф
¹ԲǽʥץΥꥹȤƤ롣˼¹Ԥץ
ꤹ뤿ˡLinux Υ塼顼Ūͥ٤κǤ⤤
ǤʤꥹȤõơΥꥹȤƬΥץФ
塼ˤϤ줾ΥץƱŪͥ٤
ץΥꥹȤΤɤ졢ΥꥹȤɤΤ褦
ư뤫ꤹ롣

\fISCHED_OTHER\fR ϥǥեȤΰŪʻʬ䷿塼ˤǡ
¿ΥץˤäƻѤ롣\fISCHED_FIFO\fR \fISCHED_RR\fR
Ϥɤμ¹Բǽץ򤹤뤫ˤĤơΤɬפȤ
֤󤬸üʥץꥱΤΤΤǤ롣
\fISCHED_OTHER\fR ǥ塼󥰤ƤץŪͥ
Ȥ 0 ꤵʤФʤ餺\fISCHED_FIFO\fR  \fISCHED_RR\fR
ǥ塼󥰤Ƥץ 1  99 ϰϤ
Ūͥ٤뤳ȤǤ롣
ѡ桼øĥץΤߤ 0 礭Ūͥ٤
뤳ȤǤ\fISCHED_FIFO\fR  \fISCHED_RR\fR ǥ塼
Ǥ롣\fBsched_get_priority_min\fR  \fBsched_get_priority_max\fR
ƥࡦѤ뤳ȤƤ POSIX.1b ߴƥ
ܿǽˡͭͥ٤ϰϤ뤳ȤǤ롣

ƤΥ塼󥰤ϥץꥨץƥ(preemptive)Ǥ: 
⤤ͥ٤Υץμ¹ԤνǤȡߤΥץ
ͥŪʤΤ֤(preempt)ԤꥹȤᤵ롣
塼ˤƱŪͥ٤ļ¹Բǽʥץ
ꥹȤǽ֤Τߤꤹ롣

.SS SCHED_FIFO: եȥ󡦥եȥȡ塼
\fISCHED_FIFO\fR  0 礭Ūͥ٤ǤΤ߻ѤǤ
\fISCHED_FIFO\fR ץ¹Բǽˤʤä硢ˡ
߼¹ԤƤ̤ \fISCHED_OTHER\fR ץ֤
\fISCHED_FIFO\fR ϻʬΤʤñʥ塼󥰡르ꥺǤ롣
\fISCHED_FIFO\fR ˤǥ塼󥰤Ƥץˤϰʲ
§ŬѤ: ⤤ͥ٤¾Υץˤä֤줿
\fISCHED_FIFO\fR ץϤͥ٤ΥꥹȤƬαޤ³
⤤ͥ٤ΥץƤ(block)ˤϺƤӼ¹Ԥ³롣
\fISCHED_FIFO\fR ץ¹Բǽˤʤäͥ٤ΥꥹȤκǸ
롣\fBsched_setscheduler\fR  \fBsched_setparam\fR 
\fIpid\fR ǻꤵ줿 \fISCHED_FIFO\fR ץ¹Բǽʾ硢
ꥹȤκǸ֤\fBsched_yield\fR ƤӽФץϥꥹȤ
Ǹ֤롣¾Υ٥Ȥˤä \fISCHED_FIFO\fR ˤ
塼󥰤ץƱͥ٤μ¹Բǽʥץ
ԤꥹȤư뤳ȤϤʤ\fISCHED_FIFO\fR ץ
I/O ׵ˤäߤ뤫⤤ͥ٤Υץˤä֤
뤫\fBsched_yield\fR ƤӽФޤǼ¹Ԥ³롣

.SS SCHED_RR: 饦ɡӥ(round robin)塼
\fISCHED_RR\fR  \fISCHED_FIFO\fR ñʳĥǤ롣
Ҥ줿 \fISCHED_FIFO\fR ˴ؤ뵭Ҥ \fISCHED_RR\fR 
ŬѤǤ롣㳰Ϥ줾ΥץϺñ̤ޤǤ¹ԤǤʤ
ȤȤǤ롣\fISCHED_RR\fR ץñ̤Ʊ
Ĺּ¹Ԥȡͥ٤ΥꥹȤκǸ֤롣

⤤ͥ٤Υץˤä֤졢θ¹ԤƳ
 \fISCHED_RR\fR ץϤΥ饦ɡӥñ̤˻Ȥڤ
ޤǼ¹Ԥ롣λñ̤Ĺ \fBsched_rr_get_interval\fR 
äƼǤ롣

.SS SCHED_OTHER: Linux ΥǥեȤλʬ䥹塼
\fISCHED_OTHER\fR Ūͥ 0 ǤΤ߻ѤǤ롣
\fISCHED_OTHER\fR  Linux ɸλʬ䥹塼顼ǡ
üŪͥ٤ꥢ롦ൡɬפȤƤʤƤ
ץǻѤ롣¹ԤץŪͥ 0 ΥꥹȤ
Τߤ顢ưŪͥ(dynamic priority)˴𤤤Ʒꤵ롣
ưŪͥ٤(\fBnice\fR  \fBsetpriority\fR ƥࡦ
äꤵ) nice ٥˴ŤƤ롣ͤϥץ
¹ԽǤƤꡢ塼顼ˤäƼ¹ԤݤƤ֡
ñ̤Ȥ˥󥯥Ȥ롣Ƥ \fISCHED_OTHER\fR 
ץ˸ʿǤ뤳Ȥݾڤ롣

.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

ꥢ롦ࡦץ񡢥ڡ󥰤Ԥ֤򤱤뤿
.B mlock 

.BR mlockall
Ȥäƥꡦå򤷤ʤФʤʤ

\fISCHED_FIFO\fR  \fISCHED_RR\fR ǥ塼󥰤
ץߤ̵¥롼פԤʤ¾ƤΤ㤤ͥ٤Υץ
ʵפ(block)ϡեȥȯԤϥ󥽡Υ
Ūͥ٤ƥȤ륢ץꥱ˹⤯ݤĤ٤Ǥ롣
ˤäƴ̤ߤ꽪λꤷʤꥢ롦ࡦ
ץꥱ۵޽λ뤳Ȥǽˤʤ롣
\fISCHED_FIFO\fR  \fISCHED_RR\fR ץϡʵפ¾Υץ
ͥ褹뤳ȤǤ롢 Linux ǤϤˤϥ롼ȤΥץ
ΤߤͿ뤳ȤǤ롣

POSIX ƥǤ <unistd.h> 
.I _POSIX_PRIORITY_SCHEDULING
ƤˤΤ
.B sched_setscheduler

.B sched_getscheduler
ѤǤ롣

.SH ֤
硢
.BR sched_setscheduler
ϥ֤
硢
.BR sched_getscheduler
ϸߤΤΥץ()֤
顼ξ硢\-1 ֤졢
.I errno
Ŭڤꤵ롣
.SH 顼
.TP
.B ESRCH
ID \fIpid\fR ΥץĤʤ
.TP
.B EPERM
ƤӽФץŬڤøäƤʤ롼ȤΥץΤߤ
\fISCHED_FIFO\fR  \fISCHED_RR\fR ˤͿ뤳ȤǤ롣
.BR sched_setscheduler
ƤӽФץϼ¸桼ID 
.IR pid 
ǻꤷץμ¸桼ID桼ID
ѡ桼ΥץǤʤФʤʤ
.TP
.B EINVAL
塼 \fIpolicy\fR ְäƤ뤫
ѥ᡼ \fIp\fR ˤǰ̣ʤʤ
.SH 
POSIX.1b ( POSIX.4)
.SH Х
linux-1.3.81 ˤơ\fISCHED_RR\fR ϤۤǫˤϥƥȤ
ʤᡢ Τˤ POSIX.1b ˵Ҥ׵ᤵ褦ư򤷤Ƥ
ʤ⤷ʤ
.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) Τ褦ʥꥢ륿ĥ줿 
Linux 丷ꥢ롦ॢץꥱѤ߷פ줿
¾ OS λѤθ٤Ǥ롣
.SH Ϣ
.BR sched_setparam (2), 
.BR sched_getparam (2), 
.BR sched_yield (2), 
.BR sched_get_priority_max (2), 
.BR sched_get_priority_min (2), 
.BR nice (2), 
.BR setpriority (2), 
.BR getpriority (2), 
.BR mlockall (2), 
.BR munlockall (2), 
.BR mlock (2), 
.BR munlock (2).
.PP
.I Programming for the real world \- POSIX.4
by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0
.br
.I IEEE Std 1003.1b-1993
(POSIX.1b )
.br
.I ISO/IEC 9945-1:1996
\- Ͽ POSIX.1 1996ǯǤǤꡢ
POSIX.1(1990), POSIX.1b(1993), POSIX.1c(1995), POSIX.1i(1995)
ƤεʤޤǤ롣