swap_pager.h revision 42957 
1/*
2 * Copyright (c) 1990 University of Utah.
3 * Copyright (c) 1991 The Regents of the University of California.
4 * All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * the Systems Programming Group of the University of Utah Computer
8 * Science Department.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by the University of
21 *	California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 *	from: @(#)swap_pager.h	7.1 (Berkeley) 12/5/90
39 *	$Id: swap_pager.h,v 1.22 1998/07/10 21:50:17 alex Exp $
40 */
41
42/*
43 * Modifications to the block allocation data structure by John S. Dyson
44 * 18 Dec 93.
45 */
46
47#ifndef	_SWAP_PAGER_
48#define	_SWAP_PAGER_	1
49
50/*
51 * SWB_NPAGES can be set to any value from 1 to 16 pages per allocation,
52 * however, due to the allocation spilling into non-swap pager backed memory,
53 * suggest keeping SWB_NPAGES small (1-4).  If high performance is mandatory
54 * perhaps up to 8 pages might be in order????
55 * Above problem has been fixed, now we support 16 pages per block.  Unused
56 * space is recovered by the swap pager now...
57 */
58#if !defined(SWB_NPAGES)
59#define SWB_NPAGES 8
60#endif
61
62/*
63 * Piecemeal swap metadata structure.  Swap is stored in a radix tree.
64 *
65 * If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix
66 * is basically 8.  Assuming PAGE_SIZE == 4096, one tree level represents
67 * 32K worth of data, two levels represent 256K, three levels represent
68 * 2 MBytes.   This is acceptable.
69 *
70 * Overall memory utilization is about the same as the old swap structure.
71 */
72
73#define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
74
75#define SWAP_META_PAGES		(SWB_NPAGES * 2)
76#define SWAP_META_MASK		(SWAP_META_PAGES - 1)
77
78struct swblock {
79	struct swblock	*swb_hnext;
80	vm_object_t	swb_object;
81	int		swb_index;
82	int		swb_count;
83	daddr_t		swb_pages[SWAP_META_PAGES];
84};
85
86#ifdef KERNEL
87extern struct pagerlst swap_pager_un_object_list;
88extern int swap_pager_full;
89extern struct blist *swapblist;
90
91int swap_pager_putpages __P((vm_object_t, vm_page_t *, int, boolean_t, int *));
92boolean_t swap_pager_haspage __P((vm_object_t object, vm_pindex_t pindex, int *before, int *after));
93
94int swap_pager_swp_alloc __P((vm_object_t, int));
95void swap_pager_copy __P((vm_object_t, vm_object_t, vm_pindex_t, int));
96void swap_pager_freespace __P((vm_object_t, vm_pindex_t, vm_size_t));
97void swap_pager_dmzspace __P((vm_object_t, vm_pindex_t, vm_size_t));
98void swap_pager_swap_init __P((void));
99
100/*
101 * newswap functions
102 */
103
104void swap_pager_page_removed __P((vm_page_t, vm_object_t));
105
106#endif
107
108#endif				/* _SWAP_PAGER_ */
109