document kpreempt_disable, kpreempt_enable, and kpreempt_disabled.

share/man/man9/Makefile

@@ -1,4 +1,4 @@
-#       $NetBSD: Makefile,v 1.262 2008/05/03 09:43:40 plunky Exp $
+#       $NetBSD: Makefile,v 1.263 2008/05/06 08:34:35 yamt Exp $
 
 #	Makefile for section 9 (kernel function and variable) manual pages.
 
@@ -304,6 +304,10 @@ MLINKS+=isapnp.9 isapnp_devmatch.9 \
 	isapnp.9 isapnp_unconfig.9
 MLINKS+=knote.9 KNOTE.9 \
 	kfilter_register.9 kfilter_unregister.9
+MAN+=	kpreempt.9
+MLINKS+=kpreempt.9 kpreempt_disable.9 \
+	kpreempt.9 kpreempt_disabled.9 \
+	kpreempt.9 kpreempt_enable.9
 MLINKS+=kprintf.9 printf.9 kprintf.9 printf_nolog.9 kprintf.9 sprintf.9 \
 	kprintf.9 snprintf.9 kprintf.9 vprintf.9 kprintf.9 vsprintf.9 \
 	kprintf.9 vsnprintf.9 kprintf.9 uprintf.9 kprintf.9 ttyprintf.9 \

share/man/man9/kpreempt.9

@@ -0,0 +1,79 @@
+.\"	$NetBSD: kpreempt.9,v 1.1 2008/05/06 08:34:35 yamt Exp $
+.\"
+.\" Copyright (c)2008 YAMAMOTO Takashi,
+.\" 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 AUTHOR AND CONTRIBUTORS ``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 AUTHOR OR CONTRIBUTORS 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.
+.\"
+.\" ------------------------------------------------------------
+.Dd May 6, 2008
+.Dt KPREEMPT 9
+.Os
+.\" ------------------------------------------------------------
+.Sh NAME
+.Nm kpreempt
+.Nd control kernel preemption
+.\" ------------------------------------------------------------
+.Sh SYNOPSIS
+.In sys/systm.h
+.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+.Ft void
+.Fn kpreempt_disable \
+"void"
+.Ft void
+.Fn kpreempt_enable \
+"void"
+.Ft bool
+.Fn kpreempt_disabled \
+"void"
+.\" ------------------------------------------------------------
+.Sh DESCRIPTION
+These functions are used to control kernel preemption of the calling LWP.
+.Pp
+Kernel preemption is currently disabled by default.
+It can be enabled by tweaking kern.sched.kpreempt_pri sysctl.
+.Pp
+.Fn kpreempt_disable
+disables kernel preemption of the calling LWP.
+Note that disabling kernel preemption can prevent LWPs with higher priorities
+from running.
+.Pp
+.Fn kpreempt_enable
+enables kernel preemption of the calling LWP, which was previously disabled by
+.Fn kpreempt_disable .
+.Pp
+.Fn kpreempt_disable
+and
+.Fn kpreempt_enable
+can be nested.
+.Pp
+.Fn kpreempt_disabled
+returns
+.Dv true
+if preemption of the calling LWP is disabled.
+It's for diagnostic purpose.
+.\" ------------------------------------------------------------
+.\" .Sh RETURN VALUES
+.\" ------------------------------------------------------------
+.Sh SEE ALSO
+.Xr intro 9 ,
+.Xr spl 9