472351e13d
.In header.h instead of .Fd #include \*[Lt]header.h\*[Gt] Much easier to read and write, and supported by groff for ages. Okayed by ross.
97 lines
3.4 KiB
Groff
97 lines
3.4 KiB
Groff
.\" $NetBSD: cpu_idle.9,v 1.3 2003/04/16 13:35:26 wiz Exp $
|
|
.\"
|
|
.\" Copyright (c) 2002 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to The NetBSD Foundation
|
|
.\" by Gregory McGarry.
|
|
.\"
|
|
.\" 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.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the NetBSD
|
|
.\" Foundation, Inc. and its contributors.
|
|
.\" 4. Neither the name of The NetBSD Foundation nor the names of its
|
|
.\" contributors may be used to endorse or promote products derived
|
|
.\" from this software without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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 September 21, 2002
|
|
.Dt CPU_IDLE 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm cpu_idle
|
|
.Nd idle CPU while waiting for work
|
|
.Sh SYNOPSIS
|
|
.In sys/proc.h
|
|
.Ft void
|
|
.Fn cpu_idle "void"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn cpu_idle
|
|
function is invoked to idle the current CPU while waiting for work to be done.
|
|
It is primarily called by the scheduler if no processes are
|
|
available on the system run queue.
|
|
The
|
|
.Fn cpu_idle
|
|
function is a machine-dependent implementations in order to permit
|
|
low-level CPU control.
|
|
.Pp
|
|
The
|
|
.Fn cpu_idle
|
|
function must be called with the scheduler lock held
|
|
.P see Xr SCHED_LOCK 9
|
|
and at the
|
|
.Xr splsched 9
|
|
interrupt protection level.
|
|
It performs the following operations:
|
|
.Bl -bullet
|
|
.It
|
|
Release the scheduler lock.
|
|
.It
|
|
Lower the current interrupt priority level to permit interrupts to be
|
|
taken that will eventually cause processes to appear again on the
|
|
system run queue.
|
|
.It
|
|
Try to zero some pages for the virtual memory system.
|
|
.It
|
|
Perform any CPU or system power control.
|
|
.It
|
|
Wait until a process appears on the system run queue.
|
|
.It
|
|
Acquire the scheduler lock.
|
|
.El
|
|
.Pp
|
|
For CPUs which don't support an idle operation, the CPU must spin
|
|
until a process appears on the system run queue.
|
|
Generally, this is done by checking if the
|
|
.Va sched_whichqs
|
|
variable in the scheduler is not zero.
|
|
See
|
|
.Xr setrunqueue 9
|
|
for further details.
|
|
.Sh SEE ALSO
|
|
.Xr mi_switch 9 ,
|
|
.Xr scheduler 9 ,
|
|
.Xr setrunqueue 9 ,
|
|
.Xr spl 9 ,
|
|
.Xr uvm 9
|