kernel - simplify vm pager ops, add pre-faulting for zero-fill pages.
[dragonfly.git] / sys / vm / phys_pager.c
CommitLineData
984263bc
MD
1/*
2 * Copyright (c) 2000 Peter Wemm
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 *
25 * $FreeBSD: src/sys/vm/phys_pager.c,v 1.3.2.3 2000/12/17 02:05:41 alfred Exp $
57f7b636 26 * $DragonFly: src/sys/vm/phys_pager.c,v 1.5 2006/03/27 01:54:18 dillon Exp $
984263bc
MD
27 */
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/linker_set.h>
32#include <sys/conf.h>
33#include <sys/mman.h>
34#include <sys/sysctl.h>
35
36#include <vm/vm.h>
37#include <vm/vm_object.h>
38#include <vm/vm_page.h>
39#include <vm/vm_pager.h>
40#include <vm/vm_zone.h>
41
654a39f0
MD
42#include <sys/thread2.h>
43
984263bc
MD
44/* list of device pager objects */
45static struct pagerlst phys_pager_object_list;
46
47static int phys_pager_alloc_lock, phys_pager_alloc_lock_want;
48
49static void
50phys_pager_init(void)
51{
52
53 TAILQ_INIT(&phys_pager_object_list);
54}
55
56static vm_object_t
57f7b636 57phys_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
984263bc
MD
58{
59 vm_object_t object;
60
61 /*
62 * Offset should be page aligned.
63 */
64 if (foff & PAGE_MASK)
65 return (NULL);
66
67 size = round_page(size);
68
69 if (handle != NULL) {
70 /*
71 * Lock to prevent object creation race condition.
72 */
73 while (phys_pager_alloc_lock) {
74 phys_pager_alloc_lock_want++;
377d4740 75 tsleep(&phys_pager_alloc_lock, 0, "ppall", 0);
984263bc
MD
76 phys_pager_alloc_lock_want--;
77 }
78 phys_pager_alloc_lock = 1;
79
80 /*
81 * Look up pager, creating as necessary.
82 */
83 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
84 if (object == NULL) {
85 /*
86 * Allocate object and associate it with the pager.
87 */
88 object = vm_object_allocate(OBJT_PHYS,
89 OFF_TO_IDX(foff + size));
90 object->handle = handle;
91 TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
92 pager_object_list);
93 } else {
94 /*
95 * Gain a reference to the object.
96 */
97 vm_object_reference(object);
98 if (OFF_TO_IDX(foff + size) > object->size)
99 object->size = OFF_TO_IDX(foff + size);
100 }
101 phys_pager_alloc_lock = 0;
102 if (phys_pager_alloc_lock_want)
103 wakeup(&phys_pager_alloc_lock);
104 } else {
105 object = vm_object_allocate(OBJT_PHYS,
106 OFF_TO_IDX(foff + size));
107 }
108
109 return (object);
110}
111
112static void
113phys_pager_dealloc(vm_object_t object)
114{
115
116 if (object->handle != NULL)
117 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
118}
119
120static int
1b9d3514 121phys_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
984263bc 122{
1b9d3514 123 vm_page_t m = *mpp;
984263bc 124
654a39f0 125 crit_enter();
1b9d3514
MD
126 if ((m->flags & PG_ZERO) == 0)
127 vm_page_zero_fill(m);
128 vm_page_flag_set(m, PG_ZERO);
129 /* Switch off pv_entries */
130 vm_page_unmanage(m);
131 m->valid = VM_PAGE_BITS_ALL;
132 m->dirty = 0;
654a39f0 133 crit_exit();
984263bc
MD
134
135 return (VM_PAGER_OK);
136}
137
138static void
1b9d3514
MD
139phys_pager_putpages(vm_object_t object, vm_page_t *m, int count,
140 boolean_t sync, int *rtvals)
984263bc
MD
141{
142
143 panic("phys_pager_putpage called");
144}
145
146/*
147 * Implement a pretty aggressive clustered getpages strategy. Hint that
148 * everything in an entire 4MB window should be prefaulted at once.
149 *
150 * XXX 4MB (1024 slots per page table page) is convenient for x86,
151 * but may not be for other arches.
152 */
153#ifndef PHYSCLUSTER
154#define PHYSCLUSTER 1024
155#endif
1b9d3514 156
984263bc 157static boolean_t
1b9d3514 158phys_pager_haspage(vm_object_t object, vm_pindex_t pindex)
984263bc 159{
984263bc
MD
160 return (TRUE);
161}
162
163struct pagerops physpagerops = {
164 phys_pager_init,
165 phys_pager_alloc,
166 phys_pager_dealloc,
1b9d3514 167 phys_pager_getpage,
984263bc
MD
168 phys_pager_putpages,
169 phys_pager_haspage,
170 NULL
171};