freebsd-dev/share/man/man9/sleep.9

.\"
.\" Copyright (c) 1996 Joerg Wunsch
.\"
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\" $FreeBSD$
.\" "
.Dd December 17, 1998
.Os
.Dt SLEEP 9
.Sh NAME
.Nm sleep ,
.Nm msleep ,
.Nm tsleep ,
.Nm wakeup
.Nd wait for events
.Sh SYNOPSIS
.In sys/param.h
.In sys/systm.h
.In sys/proc.h
.Ft int
.Fn tsleep "void *ident" "int priority" "const char *wmesg" "int timo"
.Ft int
.Fn msleep "void *ident" "struct mtx *mtx" "int priority" "const char *wmesg" "int timo"
.Ft void
.Fn wakeup "void *ident"
.Ft void
.Fn wakeup_one "void *ident"
.Sh DESCRIPTION
The functions
.Fn tsleep
and
.Fn wakeup
handle event-based process blocking.  If a process must wait for an
external event, it is put on sleep by
.Nm tsleep .
The parameter
.Ar ident
is an arbitrary address that uniquely identifies the event on which
the process is being asleep.  All processes sleeping on a single
.Ar ident
are woken up later by
.Nm wakeup ,
often called from inside an interrupt routine, to indicate that the
resource the process was blocking on is available now.
.Pp
The parameter
.Ar wmesg
is a string describing the sleep condition for tools like
.Xr ps 1 .
Due to the limited space of those programs to display arbitrary strings,
this message should not be longer than 6 characters.
.Pp
The
.Fn wakeup_one
function is used to make the first process in the queue that is
sleeping on the parameter
.Fa ident
runnable.  This can prevent the system from becoming saturated
when a large number of processes are sleeping on the same address,
but only one of them can actually do any useful work when made
runnable.
.Pp
.Nm Tsleep
is the general sleep call.  Suspends the current process until a wakeup is
performed on the specified identifier.  The process will then be made
runnable with the specified
.Ar priority .
Sleeps at most
.Ar timo
\&/ hz seconds (0 means no timeout).  If
.Ar pri
includes the
.Dv PCATCH
flag, signals are checked before and after sleeping, else signals are
not checked.  Returns 0 if awakened,
.Er EWOULDBLOCK
if the timeout expires.  If
.Dv PCATCH
is set and a signal needs to be delivered,
.Er ERESTART
is returned if the current system call should be restarted if
possible, and
.Er EINTR
is returned if the system call should be interrupted by the signal
(return
.Er EINTR ) .
.Pp
.Nm Msleep
is a variation on tsleep.  The parameter
.Ar mtx
is a mutex, which will be exited before sleeping, and entered before
.Nm msleep
returns.  If
.Ar pri
includes the
.Dv PDROP
flag, the
.Ar mtx
parameter will not be entered before returning.  The mutex is
used to ensure that a condition can be checked atomically, and
that the current process can be suspended without missing a
change to the condition, or an associated wakeup.
.Sh RETURN VALUES
See above.
.Sh SEE ALSO
.Xr ps 1 ,
.Xr malloc 9 ,
.Xr mi_switch 9
.Sh HISTORY
The sleep/wakeup process synchronization mechanism is very old.  It
appeared in a very early version of
.Ux .
.Pp
.Nm Tsleep
appeared in
.Bx 4.4 .
.Pp
.Nm Sleep
used to be the traditional form.  It doesn't let you specify a timeout or a
.Ar wmesg ,
hence it has been discontinued.
.Sh AUTHORS
.An -nosplit
This man page was written by
.An J\(:org Wunsch .
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.\"`
			`.\" Copyright (c) 1996 Joerg Wunsch`
			`.\"`
			`.\" All rights reserved.`
			`.\"`
			`.\" Redistribution and use in source and binary forms, with or without`
			`.\" modification, are permitted provided that the following conditions`
			`.\" are met:`
			`.\" 1. Redistributions of source code must retain the above copyright`
			`.\" notice, this list of conditions and the following disclaimer.`
			`.\" 2. Redistributions in binary form must reproduce the above copyright`
			`.\" notice, this list of conditions and the following disclaimer in the`
			`.\" documentation and/or other materials provided with the distribution.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
			`.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES`
			`.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.`
			`.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,`
			`.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT`
			`.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,`
			`.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY`
			`.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT`
			`.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF`
			`.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.`
			`.\"`
$Id$ -> $FreeBSD$ 1999-08-28 00:22:10 +00:00			`.\" $FreeBSD$`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.\" "`
Add manual page for experimental kernel asleep() and await() routines 1998-12-21 10:29:28 +00:00			`.Dd December 17, 1998`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Os`
			`.Dt SLEEP 9`
			`.Sh NAME`
List tsleep & wakeup in the summary line so that they can be found with "man -k". 1996-04-05 21:08:40 +00:00			`.Nm sleep ,`
Add scant documentation for msleep. 2000-09-11 00:52:31 +00:00			`.Nm msleep ,`
List tsleep & wakeup in the summary line so that they can be found with "man -k". 1996-04-05 21:08:40 +00:00			`.Nm tsleep ,`
			`.Nm wakeup`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Nd wait for events`
			`.Sh SYNOPSIS`
mdoc(7) police: Use the new .In macro for #include statements. 2001-10-01 16:09:29 +00:00			`.In sys/param.h`
			`.In sys/systm.h`
			`.In sys/proc.h`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Ft int`
Fixed prototype for tsleep() (const poisoning). 1998-01-16 18:12:57 +00:00			`.Fn tsleep "void ident" "int priority" "const char wmesg" "int timo"`
Add manual page for experimental kernel asleep() and await() routines 1998-12-21 10:29:28 +00:00			`.Ft int`
Replace non-existent 'mtx_t' typedef'd type with 'struct mtx'. 2000-11-10 01:51:55 +00:00			`.Fn msleep "void ident" "struct mtx mtx" "int priority" "const char *wmesg" "int timo"`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Ft void`
			`.Fn wakeup "void *ident"`
Document wakeup_one(). 1997-04-09 05:39:32 +00:00			`.Ft void`
			`.Fn wakeup_one "void *ident"`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Sh DESCRIPTION`
			`The functions`
			`.Fn tsleep`
			`and`
			`.Fn wakeup`
			`handle event-based process blocking. If a process must wait for an`
			`external event, it is put on sleep by`
			`.Nm tsleep .`
			`The parameter`
			`.Ar ident`
			`is an arbitrary address that uniquely identifies the event on which`
Fix a typo. 1996-04-06 13:33:23 +00:00			`the process is being asleep. All processes sleeping on a single`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Ar ident`
			`are woken up later by`
			`.Nm wakeup ,`
			`often called from inside an interrupt routine, to indicate that the`
			`resource the process was blocking on is available now.`
			`.Pp`
			`The parameter`
			`.Ar wmesg`
			`is a string describing the sleep condition for tools like`
			`.Xr ps 1 .`
			`Due to the limited space of those programs to display arbitrary strings,`
			`this message should not be longer than 6 characters.`
			`.Pp`
Document wakeup_one(). 1997-04-09 05:39:32 +00:00			`The`
			`.Fn wakeup_one`
			`function is used to make the first process in the queue that is`
			`sleeping on the parameter`
			`.Fa ident`
Removed whitespace at end-of-line; no content changes. I simply did cd src/share; find man[1-9] -type f\|xargs perl -pi -e 's/[ \t]+$//' BTW, what editors are the culprits? I'm using vim and it shows me whitespace at EOL in troff files with a thick blue block... Reviewed by: Silence from cvs diff -b MFC after: 7 days 2001-07-14 19:41:16 +00:00			`runnable. This can prevent the system from becoming saturated`
Document wakeup_one(). 1997-04-09 05:39:32 +00:00			`when a large number of processes are sleeping on the same address,`
			`but only one of them can actually do any useful work when made`
			`runnable.`
			`.Pp`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Nm Tsleep`
			`is the general sleep call. Suspends the current process until a wakeup is`
			`performed on the specified identifier. The process will then be made`
			`runnable with the specified`
			`.Ar priority .`
			`Sleeps at most`
			`.Ar timo`
			`\&/ hz seconds (0 means no timeout). If`
			`.Ar pri`
			`includes the`
.Ql --> .Dv Submitted by: wollman 1996-04-05 23:23:25 +00:00			`.Dv PCATCH`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`flag, signals are checked before and after sleeping, else signals are`
			`not checked. Returns 0 if awakened,`
mdoc(7) police: Er macro usage cleanup. 2000-11-22 16:11:48 +00:00			`.Er EWOULDBLOCK`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`if the timeout expires. If`
.Ql --> .Dv Submitted by: wollman 1996-04-05 23:23:25 +00:00			`.Dv PCATCH`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`is set and a signal needs to be delivered,`
mdoc(7) police: Er macro usage cleanup. 2000-11-22 16:11:48 +00:00			`.Er ERESTART`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`is returned if the current system call should be restarted if`
			`possible, and`
mdoc(7) police: Er macro usage cleanup. 2000-11-22 16:11:48 +00:00			`.Er EINTR`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`is returned if the system call should be interrupted by the signal`
mdoc(7) police: Avoid using parenthesis enclosure macros (.Pq and .Po/.Pc) with plain text. Not only this slows down the mdoc(7) processing significantly, but it also has an undesired (in this case) effect of disabling hyphenation within the entire enclosed block. 2001-08-07 15:48:51 +00:00			`(return`
			`.Er EINTR ) .`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Pp`
Add scant documentation for msleep. 2000-09-11 00:52:31 +00:00			`.Nm Msleep`
			`is a variation on tsleep. The parameter`
			`.Ar mtx`
			`is a mutex, which will be exited before sleeping, and entered before`
			`.Nm msleep`
			`returns. If`
			`.Ar pri`
			`includes the`
			`.Dv PDROP`
			`flag, the`
			`.Ar mtx`
			`parameter will not be entered before returning. The mutex is`
Fix speling errur. 2001-12-05 02:55:23 +00:00			`used to ensure that a condition can be checked atomically, and`
Add scant documentation for msleep. 2000-09-11 00:52:31 +00:00			`that the current process can be suspended without missing a`
			`change to the condition, or an associated wakeup.`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Sh RETURN VALUES`
			`See above.`
			`.Sh SEE ALSO`
update asleep/await sections 1998-12-23 00:24:59 +00:00			`.Xr ps 1 ,`
Improve the cross-references. 2000-08-15 15:14:13 +00:00			`.Xr malloc 9 ,`
			`.Xr mi_switch 9`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Sh HISTORY`
Fix some typos. 1996-04-07 08:37:54 +00:00			`The sleep/wakeup process synchronization mechanism is very old. It`
mdoc(7) police: macroize UNIX. 2002-03-18 10:43:49 +00:00			`appeared in a very early version of`
			`.Ux .`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Pp`
			`.Nm Tsleep`
			`appeared in`
			`.Bx 4.4 .`
update HISTORY section 1998-12-21 10:34:53 +00:00			`.Pp`
Move the description of the traditional sleep() form out into the history section, we no longer have it. Fix mdoc style violations caused by a previous committer. 1999-11-03 10:39:54 +00:00			`.Nm Sleep`
Small grammar gnit. 2000-05-09 20:35:13 +00:00			`used to be the traditional form. It doesn't let you specify a timeout or a`
Move the description of the traditional sleep() form out into the history section, we no longer have it. Fix mdoc style violations caused by a previous committer. 1999-11-03 10:39:54 +00:00			`.Ar wmesg ,`
			`hence it has been discontinued.`
Populate this. :) Add a man page for tsleep()/wakeup(). 1996-04-03 07:41:27 +00:00			`.Sh AUTHORS`
mdoc(7) police: do not split author names in the AUTHORS section. 2000-11-22 09:35:58 +00:00			`.An -nosplit`
Fix grammar and a function name. 2000-08-15 15:09:13 +00:00			`This man page was written by`
Avoid use of direct troff requests in mdoc(7) manual pages. 2000-11-10 17:46:15 +00:00			`.An J\(:org Wunsch .`