85 lines
2.9 KiB
Groff
85 lines
2.9 KiB
Groff
.\"
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.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
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.\" Copyright (c) 2013 The FreeBSD Foundation
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.\"
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.\" Portions of this documentation were written by Konstantin Belousov
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.\" under sponsorship from the FreeBSD Foundation.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
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.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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.\" DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd August 23, 2013
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.Dt VM_PAGE_GRAB 9
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.Os
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.Sh NAME
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.Nm vm_page_grab
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.Nd "returns a page from an object"
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.Sh SYNOPSIS
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.In sys/param.h
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.In vm/vm.h
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.In vm/vm_page.h
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.Ft vm_page_t
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.Fn vm_page_grab "vm_object_t object" "vm_pindex_t pindex" "int allocflags"
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.Sh DESCRIPTION
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The
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.Fn vm_page_grab
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function returns the page at
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.Fa pindex
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from the given object.
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If the page exists and is busy,
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.Fn vm_page_grab
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will sleep while waiting for it.
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If the page does not exist, it is allocated.
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The function sleeps until the allocation request can be satisfied.
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.Pp
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The function requires the
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.Fa object
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to be locked on entry, and returns with the object locked.
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If the
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.Fn vm_page_grab
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function sleeps for any reason, the object lock is temporary dropped.
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.Pp
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The
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.Fn vm_page_grab
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supports all of the flags supported by
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.Xr vm_page_alloc .
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In addition,
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.Fn vm_page_grab
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supports the following flags:
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.Bl -tag -width ".Dv VM_ALLOC_IGN_SBUSY"
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.It Dv VM_ALLOC_IGN_SBUSY
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When waiting for the busy state of the existing page to drain,
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only test for exclusive busy; ignore the shared busy counter.
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.El
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.Sh RETURN VALUES
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The
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.Fn vm_page_grab
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always returns the page.
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.Sh SEE ALSO
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.Xr vm_page_alloc 9
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.Sh AUTHORS
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This manual page was written by
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.An Chad David Aq davidc@acns.ab.ca .
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