103 lines
3.3 KiB
Groff
103 lines
3.3 KiB
Groff
.\"
|
|
.\" 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 13, 2001
|
|
.Dt VM_PAGE_ALLOC 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm vm_page_alloc
|
|
.Nd "allocate a page for a"
|
|
.Vt vm_object
|
|
.Sh SYNOPSIS
|
|
.In sys/param.h
|
|
.In vm/vm.h
|
|
.In vm/vm_page.h
|
|
.Ft vm_page_t
|
|
.Fn vm_page_alloc "vm_object_t object" "vm_pindex_t pindex" "int page_req"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn vm_page_alloc
|
|
function allocates a page at
|
|
.Fa pindex
|
|
within
|
|
.Fa object .
|
|
It is assumed that a page has not already been allocated at
|
|
.Fa pindex .
|
|
The page returned is inserted into the object, but is not inserted
|
|
into the pmap.
|
|
.Pp
|
|
.Fn vm_page_alloc
|
|
will not block.
|
|
.Pp
|
|
Its arguments are:
|
|
.Bl -tag -width ".Fa page_req"
|
|
.It Fa object
|
|
The VM object to allocate the page for.
|
|
.It Fa pindex
|
|
The index into the object at which the page should be inserted.
|
|
.It Fa page_req
|
|
A flag indicating how the page should be allocated.
|
|
.Bl -tag -width ".Dv VM_ALLOC_INTERRUPT"
|
|
.It Dv VM_ALLOC_NORMAL
|
|
The page should be allocated with no special treatment.
|
|
.It Dv VM_ALLOC_SYSTEM
|
|
The page can be allocated if the cache queue is empty and the free
|
|
page count is above the interrupt reserved water mark.
|
|
If
|
|
.Dv VM_ALLOC_INTERRUPT
|
|
is set, the page can be allocated as long as the free page count is
|
|
greater than zero.
|
|
This flag should be used only when the system really needs the page.
|
|
.It Dv VM_ALLOC_INTERRUPT
|
|
.Fn vm_page_alloc
|
|
is being called during an interrupt and therefore the cache cannot
|
|
be accessed.
|
|
The page will only be returned successfully if the free count is greater
|
|
than zero.
|
|
.It Dv VM_ALLOC_ZERO
|
|
The same as
|
|
.Dv VM_ALLOC_NORMAL
|
|
except the page returned is zeroed.
|
|
.El
|
|
.El
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Vt vm_page_t
|
|
that was allocated is returned if successful; otherwise,
|
|
.Dv NULL
|
|
is returned.
|
|
.Sh NOTES
|
|
The pager process is always upgraded to
|
|
.Dv VM_ALLOC_SYSTEM
|
|
unless
|
|
.Dv VM_ALLOC_INTERRUPT
|
|
is set.
|
|
.Sh AUTHORS
|
|
This man page was written by
|
|
.An Chad David Aq davidc@acns.ab.ca .
|