1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
|
.\"
.\" 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 February 27, 2010
.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, unless
.Dv VM_ALLOC_NOOBJ
is specified in the
.Fa page_req ,
but is not inserted into a pmap.
The page may exists in the vm object cache, in which case it will
be reactivated instead, moving from the cache into the object page list.
.Pp
.Fn vm_page_alloc
will not sleep.
.Pp
Its arguments are:
.Bl -tag -width ".Fa page_req"
.It Fa object
The VM object to allocate the page for.
The
.Fa object
must be locked if
.Dv VM_ALLOC_NOOBJ
is not specified.
.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
Indicate a preference for a pre-zeroed page.
There is no guarantee that the page thus returned will be zeroed, but
it will be marked by
.Dv PG_ZERO
flag if it is zeroed.
.It Dv VM_ALLOC_NOOBJ
Do not associate the allocated page with a vm object.
The
.Fa object
argument is ignored.
.It Dv VM_ALLOC_NOBUSY
The page returned will not be busied.
.It Dv VM_ALLOC_WIRED
The returned page is wired.
.It Dv VM_ALLOC_IFNOTCACHED
Only allocate the page if it is not cached in the
.Fa object .
If the page at the specified
.Fa pindex
is cached, NULL is returned instead.
.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 manual page was written by
.An Chad David Aq davidc@acns.ab.ca .
|
