NetBSD/share/man/man9/cpu_idle.9

.\"	$NetBSD: cpu_idle.9,v 1.9 2007/04/20 13:45:43 yamt Exp $
.\"
.\" Copyright (c)2007 YAMAMOTO Takashi,
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.\" ------------------------------------------------------------
.Dd April 20, 2007
.Dt CPU_IDLE 9
.Os
.\" ------------------------------------------------------------
.Sh NAME
.Nm cpu_idle
.Nd machine-dependent processor idling interface
.\" ------------------------------------------------------------
.Sh SYNOPSIS
.In sys/cpu.h
.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
.Ft void
.Fn cpu_idle \
"void"
.\" ------------------------------------------------------------
.Sh DESCRIPTION
.Fn cpu_idle
is called by machine-independent code when the processor has
nothing to do.
It can be used to conserve the processor power, for example.
.Pp
.Fn cpu_idle
returns immediately if
.Fn cpu_need_resched
has been called for the processor after
the last call of
.Fn cpu_idle
or
.Fn cpu_did_resched
on the processor.
.Fn cpu_idle
returns as soon as possible when
.Fn cpu_need_resched
is called for the processor.
Otherwise, it returns whenever it likes.
.Pp
.Fn cpu_idle
is called at
.Dv IPL_NONE ,
without any locks held.
.\" ------------------------------------------------------------
.Sh EXAMPLES
The simplest (and, in some cases, the best) implementation of
.Fn cpu_idle
is the following.
.Bd -literal
	void
	cpu_idle(void)
	{
		/* nothing */
	}
.Ed
.\" ------------------------------------------------------------
.Sh SEE ALSO
.Xr cpu_need_resched 9 ,
.Xr cpu_switchto 9 ,
.Xr intro 9 ,
.Xr spl 9