FreeBSD-5.3/share/man/man9/vm_page_io.9

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.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
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.\" $FreeBSD: src/share/man/man9/vm_page_io.9,v 1.4 2004/05/05 10:01:06 hmp Exp $
.\"
.Dd July 17, 2001
.Dt VM_PAGE_IO_START 9
.Os
.Sh NAME
.Nm vm_page_io_start ,
.Nm vm_page_io_finish
.Nd "ready or unready a page for I/O"
.Sh SYNOPSIS
.In sys/param.h
.In vm/vm.h
.In vm/vm_page.h
.Ft void
.Fn vm_page_io_start "vm_page_t m"
.Ft void
.Fn vm_page_io_finish "vm_page_t m"
.Sh DESCRIPTION
The
.Fn vm_page_io_start
function prepares the page for I/O by incrementing its busy flag by one.
.Pp
The
.Fn vm_page_io_finish
function lowers the busy count on the page by one, if the resulting busy
count is zero, a
.Xr wakeup 9
will be issued if the page has been marked
.Dv PG_WANTED .
A page is typically marked
.Dv PG_WANTED
by a thread to register its interest in
the page to either complete I/O or becoming available for general use.
.Sh AUTHORS
.An -nosplit
This man page was written by
.An Chad David Aq davidc@acns.ab.ca
and
.An Alfred Perlstein Aq alfred@FreeBSD.org .