xref: /freebsd/share/man/man9/vm_page_alloc.9 (revision 6484c361f7e7653b251d7e1679bce9fe25bec281)
16484c361SAlfred Perlstein.\"
26484c361SAlfred Perlstein.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
36484c361SAlfred Perlstein.\"
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86484c361SAlfred Perlstein.\"    notice(s), this list of conditions and the following disclaimer as
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116484c361SAlfred Perlstein.\" 2. Redistributions in binary form must reproduce the above copyright
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276484c361SAlfred Perlstein.\" $FreeBSD$
286484c361SAlfred Perlstein.\"
296484c361SAlfred Perlstein.Dd July 13, 2001
306484c361SAlfred Perlstein.Dt VM_PAGE_ALLOC 9
316484c361SAlfred Perlstein.Os
326484c361SAlfred Perlstein.Sh NAME
336484c361SAlfred Perlstein.Nm vm_page_alloc
346484c361SAlfred Perlstein.Nd "allocates a page for the object and index"
356484c361SAlfred Perlstein.Sh SYNOPSIS
366484c361SAlfred Perlstein.In sys/param.h
376484c361SAlfred Perlstein.In vm/vm.h
386484c361SAlfred Perlstein.In vm/vm_page.h
396484c361SAlfred Perlstein.Ft vm_page_t
406484c361SAlfred Perlstein.Fn vm_page_alloc "vm_object_t object" "vm_pindex_t pindex" "int page_req"
416484c361SAlfred Perlstein.Sh DESCRIPTION
426484c361SAlfred PerlsteinThe
436484c361SAlfred Perlstein.Fn vm_page_alloc
446484c361SAlfred Perlsteinfunction allocates a page for
456484c361SAlfred Perlstein.Fa pindex
466484c361SAlfred Perlsteinin the VM object
476484c361SAlfred Perlstein.Fa object .
486484c361SAlfred PerlsteinIt is assumed that a page has not already been allocated for
496484c361SAlfred Perlstein.Fa pindex
506484c361SAlfred Perlsteinand
516484c361SAlfred Perlstein.Fa object .
526484c361SAlfred Perlstein.Pp
536484c361SAlfred PerlsteinThe
546484c361SAlfred Perlstein.Fn vm_page_alloc
556484c361SAlfred Perlsteinfunction will not block.
566484c361SAlfred Perlstein.Pp
576484c361SAlfred PerlsteinIts arguments are:
586484c361SAlfred Perlstein.Bl -tag -width ".Fa page_req"
596484c361SAlfred Perlstein.It Fa object
606484c361SAlfred PerlsteinThe VM object to allocate the page for.
616484c361SAlfred Perlstein.It Fa pindex
626484c361SAlfred PerlsteinThe index of the page that should be allocated.
636484c361SAlfred Perlstein.It Fa page_req
646484c361SAlfred PerlsteinA flag indicating how the page should be allocated.
656484c361SAlfred Perlstein.Bl -tag -width ".Dv VM_ALLOC_INTERRUPT"
666484c361SAlfred Perlstein.It Dv VM_ALLOC_NORMAL
676484c361SAlfred PerlsteinThe page should be allocated with no special treatment.
686484c361SAlfred Perlstein.It Dv VM_ALLOC_SYSTEM
696484c361SAlfred PerlsteinThe page can be allocated even if the buffer cache queue is empty
706484c361SAlfred Perlsteinand the free count is above the interrupt reserved water mark.
716484c361SAlfred PerlsteinThis should be used only when the system really needs the page.
726484c361SAlfred Perlstein.It Dv VM_ALLOC_INTERRUPT
736484c361SAlfred Perlstein.Fn vm_page_alloc
746484c361SAlfred Perlsteinis being called during an interrupt and therefore the cache cannot
756484c361SAlfred Perlsteinbe accessed.
766484c361SAlfred PerlsteinThe page will only be returned successfully if the free count is greater
776484c361SAlfred Perlsteinthan zero.
786484c361SAlfred Perlstein.It Dv VM_ALLOC_ZERO
796484c361SAlfred PerlsteinThe same as
806484c361SAlfred Perlstein.Dv VM_ALLOC_NORMAL
816484c361SAlfred Perlsteinexcept the page returned is zeroed.
826484c361SAlfred Perlstein.El
836484c361SAlfred Perlstein.El
846484c361SAlfred Perlstein.Sh RETURN VALUES
856484c361SAlfred PerlsteinA
866484c361SAlfred Perlstein.Vt vm_page_t
876484c361SAlfred Perlsteinis returned if successful; otherwise,
886484c361SAlfred Perlstein.Dv NULL
896484c361SAlfred Perlsteinis returned.
906484c361SAlfred Perlstein.Sh NOTES
916484c361SAlfred PerlsteinThe pager process is always upgraded to
926484c361SAlfred Perlstein.Dv VM_ALLOC_SYSTEM
936484c361SAlfred Perlsteinunless
946484c361SAlfred Perlstein.Dv VM_ALLOC_INTERRUPT
956484c361SAlfred Perlsteinis set.
966484c361SAlfred Perlstein.Sh AUTHORS
976484c361SAlfred PerlsteinThis man page was written by
986484c361SAlfred Perlstein.An Chad David Aq davidc@acns.ab.ca .
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