2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * The Mach Operating System project at Carnegie-Mellon University.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * from: @(#)vm_pager.c 8.6 (Berkeley) 1/12/94
39 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
40 * All rights reserved.
42 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
44 * Permission to use, copy, modify and distribute this software and
45 * its documentation is hereby granted, provided that both the copyright
46 * notice and this permission notice appear in all copies of the
47 * software, derivative works or modified versions, and any portions
48 * thereof, and that both notices appear in supporting documentation.
50 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
51 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
52 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
54 * Carnegie Mellon requests users of this software to return to
56 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
57 * School of Computer Science
58 * Carnegie Mellon University
59 * Pittsburgh PA 15213-3890
61 * any improvements or extensions that they make and grant Carnegie the
62 * rights to redistribute these changes.
64 * $FreeBSD: src/sys/vm/vm_pager.c,v 1.54.2.2 2001/11/18 07:11:00 dillon Exp $
65 * $DragonFly: src/sys/vm/vm_pager.c,v 1.24 2007/11/06 03:50:01 dillon Exp $
69 * Paging space routine stubs. Emulates a matchmaker-like interface
73 #include <sys/param.h>
74 #include <sys/systm.h>
75 #include <sys/kernel.h>
76 #include <sys/vnode.h>
78 #include <sys/ucred.h>
79 #include <sys/malloc.h>
81 #include <sys/thread2.h>
84 #include <vm/vm_param.h>
85 #include <vm/vm_object.h>
86 #include <vm/vm_page.h>
87 #include <vm/vm_pager.h>
88 #include <vm/vm_extern.h>
92 MALLOC_DEFINE(M_VMPGDATA
, "VM pgdata", "XXX: VM pager private data");
94 extern struct pagerops defaultpagerops
;
95 extern struct pagerops swappagerops
;
96 extern struct pagerops vnodepagerops
;
97 extern struct pagerops devicepagerops
;
98 extern struct pagerops physpagerops
;
100 int cluster_pbuf_freecnt
= -1; /* unlimited to begin with */
102 static int dead_pager_getpage (vm_object_t
, vm_page_t
*, int);
103 static void dead_pager_putpages (vm_object_t
, vm_page_t
*, int, int, int *);
104 static boolean_t
dead_pager_haspage (vm_object_t
, vm_pindex_t
);
105 static void dead_pager_dealloc (vm_object_t
);
108 dead_pager_getpage(vm_object_t obj
, vm_page_t
*mpp
, int seqaccess
)
110 return VM_PAGER_FAIL
;
114 dead_pager_putpages(vm_object_t object
, vm_page_t
*m
, int count
, int flags
,
119 for (i
= 0; i
< count
; i
++) {
120 rtvals
[i
] = VM_PAGER_AGAIN
;
125 dead_pager_haspage(vm_object_t object
, vm_pindex_t pindex
)
131 dead_pager_dealloc(vm_object_t object
)
133 KKASSERT(object
->swblock_count
== 0);
137 static struct pagerops deadpagerops
= {
144 struct pagerops
*pagertab
[] = {
145 &defaultpagerops
, /* OBJT_DEFAULT */
146 &swappagerops
, /* OBJT_SWAP */
147 &vnodepagerops
, /* OBJT_VNODE */
148 &devicepagerops
, /* OBJT_DEVICE */
149 &physpagerops
, /* OBJT_PHYS */
150 &deadpagerops
/* OBJT_DEAD */
153 int npagers
= sizeof(pagertab
) / sizeof(pagertab
[0]);
156 * Kernel address space for mapping pages.
157 * Used by pagers where KVAs are needed for IO.
159 * XXX needs to be large enough to support the number of pending async
160 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
161 * (MAXPHYS == 64k) if you want to get the most efficiency.
163 #define PAGER_MAP_SIZE (8 * 1024 * 1024)
165 int pager_map_size
= PAGER_MAP_SIZE
;
166 struct vm_map pager_map
;
168 static int bswneeded
;
169 static vm_offset_t swapbkva
; /* swap buffers kva */
170 static TAILQ_HEAD(swqueue
, buf
) bswlist
;
171 static struct spinlock bswspin
= SPINLOCK_INITIALIZER(&bswspin
);
174 vm_pager_init(void *arg __unused
)
177 * Initialize the swap buffer list.
179 TAILQ_INIT(&bswlist
);
181 SYSINIT(vm_mem
, SI_BOOT1_VM
, SI_ORDER_SECOND
, vm_pager_init
, NULL
)
184 vm_pager_bufferinit(void)
190 * Reserve KVM space for pbuf data.
192 swapbkva
= kmem_alloc_pageable(&pager_map
, nswbuf
* MAXPHYS
);
194 panic("Not enough pager_map VM space for physical buffers");
197 * Initial pbuf setup.
200 for (i
= 0; i
< nswbuf
; ++i
, ++bp
) {
201 bp
->b_kvabase
= (caddr_t
)((intptr_t)i
* MAXPHYS
) + swapbkva
;
202 bp
->b_kvasize
= MAXPHYS
;
203 TAILQ_INSERT_HEAD(&bswlist
, bp
, b_freelist
);
209 * Allow the clustering code to use half of our pbufs.
211 cluster_pbuf_freecnt
= nswbuf
/ 2;
215 vm_pager_deallocate(vm_object_t object
)
217 (*pagertab
[object
->type
]->pgo_dealloc
) (object
);
221 * vm_pager_get_pages() - inline, see vm/vm_pager.h
222 * vm_pager_put_pages() - inline, see vm/vm_pager.h
223 * vm_pager_has_page() - inline, see vm/vm_pager.h
224 * vm_pager_page_inserted() - inline, see vm/vm_pager.h
225 * vm_pager_page_removed() - inline, see vm/vm_pager.h
232 * Called by pageout daemon before going back to sleep.
233 * Gives pagers a chance to clean up any completed async pageing
239 struct pagerops
**pgops
;
241 for (pgops
= pagertab
; pgops
< &pagertab
[npagers
]; pgops
++)
242 if (pgops
&& ((*pgops
)->pgo_sync
!= NULL
))
243 (*(*pgops
)->pgo_sync
) ();
249 * Initialize a physical buffer.
252 initpbuf(struct buf
*bp
)
254 bp
->b_qindex
= 0; /* BQUEUE_NONE */
255 bp
->b_data
= bp
->b_kvabase
;
256 bp
->b_flags
= B_PAGING
;
257 bp
->b_cmd
= BUF_CMD_DONE
;
260 bp
->b_bufsize
= MAXPHYS
;
262 xio_init(&bp
->b_xio
);
263 BUF_LOCK(bp
, LK_EXCLUSIVE
);
267 * Allocate a physical buffer
269 * There are a limited number (nswbuf) of physical buffers. We need
270 * to make sure that no single subsystem is able to hog all of them,
271 * so each subsystem implements a counter which is typically initialized
272 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and
273 * increments it on release, and blocks if the counter hits zero. A
274 * subsystem may initialize the counter to -1 to disable the feature,
275 * but it must still be sure to match up all uses of getpbuf() with
276 * relpbuf() using the same variable.
278 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
279 * relatively soon when the rest of the subsystems get smart about it. XXX
284 getpbuf(int *pfreecnt
)
288 spin_lock_wr(&bswspin
);
292 while (*pfreecnt
== 0)
293 ssleep(pfreecnt
, &bswspin
, 0, "wswbuf0", 0);
296 /* get a bp from the swap buffer header pool */
297 if ((bp
= TAILQ_FIRST(&bswlist
)) != NULL
)
300 ssleep(&bswneeded
, &bswspin
, 0, "wswbuf1", 0);
301 /* loop in case someone else grabbed one */
303 TAILQ_REMOVE(&bswlist
, bp
, b_freelist
);
307 spin_unlock_wr(&bswspin
);
314 * Allocate a physical buffer, if one is available.
316 * Note that there is no NULL hack here - all subsystems using this
317 * call understand how to use pfreecnt.
322 trypbuf(int *pfreecnt
)
326 spin_lock_wr(&bswspin
);
328 if (*pfreecnt
== 0 || (bp
= TAILQ_FIRST(&bswlist
)) == NULL
) {
329 spin_unlock_wr(&bswspin
);
332 TAILQ_REMOVE(&bswlist
, bp
, b_freelist
);
335 spin_unlock_wr(&bswspin
);
343 * Release a physical buffer
345 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
346 * relatively soon when the rest of the subsystems get smart about it. XXX
351 relpbuf(struct buf
*bp
, int *pfreecnt
)
354 int wake_freecnt
= 0;
356 KKASSERT(bp
->b_flags
& B_PAGING
);
358 spin_lock_wr(&bswspin
);
361 TAILQ_INSERT_HEAD(&bswlist
, bp
, b_freelist
);
367 if (++*pfreecnt
== 1)
371 spin_unlock_wr(&bswspin
);