More updates from Chad.

Submitted by: Chad David <davidc@acns.ab.ca>
Reviewed by: sheldonh

1 files changed, 98 insertions, 0 deletions

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+.\"
+.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. 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(s), this list of conditions and the following disclaimer as
+.\"    the first lines of this file unmodified other than the possible
+.\"    addition of one or more copyright notices.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice(s), 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 COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd July 24, 2001
+.Dt VM_PAGE_FREE 9
+.Os
+.Sh NAME
+.Nm vm_page_free
+.Nm vm_page_free_toq
+.Nm vm_page_free_zero
+.Nm vm_page_try_to_free
+.Nd "free a page"
+.Sh SYNOPSIS
+.In sys/param.h
+.In vm/vm.h
+.In vm/vm_page.h
+.Ft void
+.Fn vm_page_free "vm_page_t m"
+.Ft void
+.Fn vm_page_free_toq "vm_page_t m"
+.Ft void
+.Fn vm_page_free_zero "vm_page_t m"
+.Ft int
+.Fn vm_page_try_to_free "vm_page_t m"
+.Sh DESCRIPTION
+The
+.Fn vm_page_free_toq
+function moves a page into the free queue, and disassociates it from
+its object.
+If the page is held, wired, already free, or its busy count is not
+zero the system will panic.
+If the
+.Dv PG_ZERO
+flag is set on the page is it placed at the end of the free queue;
+otherwise, it is placed at the front.
+.Pp
+If the page's object is of type
+.Dv OBJT_VNODE
+and it is the last page associated with the object the underlying
+vnode may be freed.
+.Pp
+The
+.Fn vm_page_free
+and
+.Fn vm_page_free_zero
+functions both call
+.Fn vm_page_free_toq
+to actually free page, but
+.Fn vm_page_free_zero 
+sets the
+.Dv PG_ZERO
+flag and
+.Fn vm_page_free
+clears the
+.Dv PG_ZERO
+flag prior to the call to
+.Fn vm_page_free_toq .
+.Pp
+The
+.Fn vm_page_try_to_free
+function verifies that the page is not held, wired, busy or dirty, and
+if so marks the page as busy, drops any protection that may be set on
+the page, and frees it.
+.Sh RETURN VALUES
+.Fn vm_page_try_to_free
+returns 1 if it is able to free the page; otherwise, 0 is returned.
+.Sh SEE ALSO
+.Xr vm_page_busy 9 ,
+.Xr vm_page_hold 9 ,
+.Xr vm_page_wire 9
+.Sh AUTHORS
+This manual page was written by
+.An Chad David Aq davidc@acns.ab.ca .