.\" Page by b.hubert - may be freely modified and distributed
.\"
.\" Niki A. Rahimi (LTC Security Development, narahimi@us.ibm.com)
.\" added ERRORS section.
.\"
.\" Modified 2004-06-17 mtk
.\" Modified 2004-10-07 aeb, added FUTEX_REQUEUE, FUTEX_CMP_REQUEUE
.\"
.\" FIXME
.\" 2.6.14 adds FUTEX_WAKE_OP
.\" 2.6.18 adds (Ingo Molnar) priority inheritance support:
.\" FUTEX_LOCK_PI, FUTEX_UNLOCK_PI, and FUTEX_TRYLOCK_PI.  These need
.\" to be documented in the manual page.  Probably there is sufficient
.\" material in the kernel source file Documentation/pi-futex.txt.
.\" 2.6.25 adds FUTEX_WAKE_BITSET, FUTEX_WAIT_BITSET
.\"
.\" Japanese Version Copyright(C) 2003 Suzuki Takashi
.\"         all rights reserved.
.\" Translated Fri Oct 24 10:37:10 JST 2003
.\"         by Suzuki Takashi.
.\" Updated & Modified Sat Feb  5 14:28:53 JST 2005
.\"         by Yuichi SATO <ysato444@yahoo.co.jp>, LDP v2.01
.\" Updated & Modified Wed Jan  3 04:51:22 JST 2007 by Yuichi SATO, LDP v2.43
.\"
.\"WORD: integer                int ѿ
.\"WORD: sleep                  Ԥ
.\"WORD: wake                   
.\"WORD: wake up                
.\"
.TH FUTEX 2 2008-11-27 "Linux" "Linux Programmer's Manual"
.SH ̾
futex \- ®桼֥åΥƥॳ
.SH 
.nf
.sp
.B "#include <linux/futex.h>"
.B "#include <sys/time.h>"
.sp
.BI "int futex(int *" uaddr ", int " op ", int " val \
", const struct timespec *" timeout ,
.br
.BI "          int *" uaddr2 ", int " val3 );
.\" int *? void *? u32 *?
.fi
.SH 
.PP
.BR futex ()
ƥॳϡ
ꤷɥ쥹ͤѹΤץबԤļʤ
Υɥ쥹ФԵΥץ wake () ʤ󶡤
(ץۤʤƱФ륢ɥ쥹ƱǤϤʤ⤷ʤ
ͥϰۤʤ֤˥ޥåפ줿Ʊ
.BR futex ()
ǻȤ褦ǥޥåפ)
ŵŪˤϡfutex 
.BR futex (7)
˵Ƥ褦ˡ
ͭΥå礹νΤѤ롣
.PP
.BR futex (7)
桼֤Ƕʤλʤä硢
ͥۤ뤿˥ƥॳƤɬפ롣
ۤȤΤϡƤӽФץ sleep (Ԥ) ꡢȿФ
Ԥץ wake ꤹ뤳Ȥ̣롣
.PP
δؿƤӽФץ
.BR futex (7)
˵ҤƤ륻ޥƥ¤Ǥ뤳Ȥ׵ᤵ롣
ΥޥƥˤϰܿԲǽʥ֥̿񤯤Ȥޤޤ롣
ΤȤϸ futex Υ桼ΤۤȤɤϼºݤϥ饤֥κԤǤꡢ
̥ץꥱγȯԤǤϤʤȤȤǤ롣
.PP
.I uaddr
ϡ󥿤Ǽ롢
饤Ȥ·ä int ѿؤƤɬפ롣
¹Ԥ
.I op
𤷤ơ
.I val
ȤȤϤ롣
.PP
ߤΤȤ 5 ĤƤ:
.TP
.B FUTEX_WAIT
 futex ɥ쥹
.I uaddr
˻ꤵ줿
.I val
ޤǼƤ뤫ɤԲʬǸڤ
sleep ֤
 futex ɥ쥹Ф
.B FUTEX_WAKE
¹ԤΤԤġ
.I timeout
 NULL Ǥʤ硢Ƥ
Ԥ֤κͤɽNULL ξ̵ɽ

.I uaddr2

.I val3
̵뤵롣

.BR futex (7)
˾Ȥ餷碌ȡθƤӽФ
ȤΥǥȤ (ɽ) ˤʤä˼¹Ԥ졢
̤Υץ futex 
.B FUTEX_WAKE
¹Ԥޤ sleep 롣
.TP
.B FUTEX_WAKE
Ǥϻꤷ futex ɥ쥹ФԤ֤
(ʤ
.B FUTEX_WAIT
)  \fIval\fP ĤΥץ wake 롣

.IR timeout ,
.IR uaddr2 ,
.I val3
̵뤵롣

\fBfutex\fR(4) ˾Ȥ餷碌ȡ

ȤΥ󥯥ȤԤץȽ
futex ͤ 1 ꤵ줿 (ѲǽǤ뤳Ȥɽ) ˼¹Ԥ롣
.TP
.BR FUTEX_FD " (Linux 2.6.25 )"
Ʊ wake б뤿ᡢϥեǥץ futex 
ϢŤ롣
.\" .BR poll (2)
.\" ŬƤ롣
̤Υץ
.B FUTEX_WAKE
¹Ԥȡץ
.I val
Ϥ줿ʥֹΥʥ롣
ƤӽФץϻѸ塢֤줿եǥץ
ʤФʤʤ

.IR timeout ,
.IR uaddr2 ,
.I val3
̵뤵롣

֤ɻߤ뤿ᡢƤӽФץ
.B FUTEX_FD
֤ä
futex  up 줿ɤǧʤФʤʤ

.\" FIXME . Check that this flag does eventually get removed.
.B FUTEX_FD
ϤȤȶ礬䤹äᡢ
Linux 2.6.26 ʹߤǺƤ롣
.TP
.BR FUTEX_REQUEUE " (Linux 2.5.70 ʹ)"
ϡ
.B FUTEX_WAKE
ȤƤơ wake ƤƤΥץ
¾ futex ɬפˡ
ֽäη˽ (thundering herd)׸̤򤱤뤿Ƴ줿
θƤӽФ
.I val
ĤΥץ wake ɥ쥹
.I uaddr2
 futex ԤäƤ¾ƤΥץ٥塼ˤ롣

.I timeout

.I val3
̵뤵롣
.TP
.BR FUTEX_CMP_REQUEUE " (Linux 2.6.7 ʹ)"
ΰդ
.B FUTEX_REQUEUE
Ȥ˶礬뤿ᡢ
.B FUTEX_CMP_REQUEUE
Ƴ줿
.B FUTEX_REQUEUE
ȻƤ뤬
.I uaddr

.I val3
ޤݻƤ뤫ǽ˥å롣
ݻƤʤ硢ϥ顼
.B EAGAIN
ǼԤ롣
.I timeout
̵뤵롣
.SH ֤
.PP
ɤ¹Ԥ줿ˤäơ
֤ͤΰ̣Ѥ롣
.TP
.B FUTEX_WAIT
ץ
.B FUTEX_WAKE
θƤӽФ wake  0 ֤
ॢȤξ硢ϥ顼
.B ETIMEOUT
ǼԤ롣
futex ꤵ줿ͤʤ硢
顼
.B EWOULDBLOCK
ǼԤ롣
ʥ뤫
.RB ( signal (7)
) ¾ε wake äˤϡ顼
.B EINTR
ǼԤ롣
.TP
.B FUTEX_WAKE
wake ץο֤
.TP
.B FUTEX_FD
futex ˴ϢŤ줿ʥեǥץ֤
.TP
.B FUTEX_REQUEUE
wake ץο֤
.TP
.B FUTEX_CMP_REQUEUE
wake ץο֤
.PP
顼ξ硢Ƥ \-1 ֤ꡢ
.I errno
顼Ƥ򼨤ͤꤵ롣
.SH 顼
.TP
.B EACCES
futex ɤ߹ߥʤä
.TP
.B EAGAIN
.B FUTEX_CMP_REQUEUE
ͽʤ futex ͤĤä
(϶򼨤Ƥ뤫⤷ʤ
ξϰ
.B FUTEX_WAKE
Ȥ)
.TP
.B EFAULT
桼֤
.I timeout
ξݤ˥顼ȯ
.TP
.B EINVAL
Ƥʤޤϥڡ饤Ȥǥ顼ȯ
.TP
.B ENFILE
ץ󤵤Ƥեƥ¤ã
.TP
.B ENOSYS
.I op
̵ꤵ줿
.SH С
.PP
ǽ futex б Linux 2.5.7 Ȥ߹ޤ줿
嵭ΥޥƥȤϰۤʤ롣
ǼƤ륻ޥƥ
4 ĤΰΥƥॳϡLinux 2.5.40 Ƴ줿
Linux 2.5.70 Ǥ 1 Ĥΰɲä줿
Linux 2.6.7 Ǥ 6 ܤΰɲä줿
ϱs390 ƥ̤ΤΤǤ롣
.SH 
Υƥॳ Linux ȼǤ롣
.SH 
.PP
֤ futex ϥɥ桼ưפ˻ȤȤΤǤ복ǰȤ
տޤ줿ΤǤϤʤ
(glibc ˤϤΥƥॳФåѡؿϤʤ)
Ԥϡ֥˴Ƥꡢʲ˵󤲤 futex 桼֥饤֥
ɤ߽Ƥ뤳Ȥ׵ᤵ롣
.\" .SH 
.\" .PP
.\" futex  Hubertus Franke (IBM Thomas J. Watson Research Center),
.\" Matthew Kirkwood, Ingo Molnar (Red Hat),
.\" Rusty Russell (IBM Linux Technology Center) ߷פ
.\" Υڡ bert hubert 
.SH Ϣ
.BR futex (7)
.PP
\fIFuss, Futexes and Furwocks: Fast Userlevel Locking in Linux\fP
(proceedings of the Ottawa Linux Symposium 2002),
futex λ饤֥, futex-*.tar.bz2
<URL:ftp://ftp.nl.kernel.org/pub/linux/kernel/people/rusty/>.