2 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * 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
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * Implements bitmap resource lists.
37 * blist = blist_create(blocks)
38 * (void) blist_destroy(blist)
39 * blkno = blist_alloc(blist, count)
40 * (void) blist_free(blist, blkno, count)
41 * (void) blist_resize(&blist, count, freeextra)
45 * on creation, the entire list is marked reserved. You should
46 * first blist_free() the sections you want to make available
47 * for allocation before doing general blist_alloc()/free()
50 * SWAPBLK_NONE is returned on failure. This module is typically
51 * capable of managing up to (2^31) blocks per blist, though
52 * the memory utilization would be insane if you actually did
53 * that. Managing something like 512MB worth of 4K blocks
54 * eats around 32 KBytes of memory.
56 * $FreeBSD: src/sys/sys/blist.h,v 1.2.2.1 2003/01/12 09:23:12 dillon Exp $
57 * $DragonFly: src/sys/sys/blist.h,v 1.7 2008/08/10 22:09:51 dillon Exp $
64 #include <sys/types.h>
67 typedef int32_t swblk_t;
68 typedef u_int32_t u_swblk_t;
71 * note: currently use SWAPBLK_NONE as an absolute value rather then
74 #define SWAPBLK_MASK ((swblk_t)((u_swblk_t)-1 >> 1)) /* mask */
75 #define SWAPBLK_NONE ((swblk_t)((u_swblk_t)SWAPBLK_MASK + 1))/* flag */
78 * blmeta and bl_bitmap_t MUST be a power of 2 in size.
81 typedef struct blmeta {
83 swblk_t bmu_avail; /* space available under us */
84 u_swblk_t bmu_bitmap; /* bitmap if we are a leaf */
86 swblk_t bm_bighint; /* biggest contiguous block hint*/
89 typedef struct blist {
90 swblk_t bl_blocks; /* area of coverage */
91 int64_t bl_radix; /* coverage radix */
92 swblk_t bl_skip; /* starting skip */
93 swblk_t bl_free; /* number of free blocks */
94 blmeta_t *bl_root; /* root of radix tree */
95 swblk_t bl_rootblks; /* swblk_t blks allocated for tree */
98 #define BLIST_META_RADIX 16
99 #define BLIST_BMAP_RADIX (sizeof(u_swblk_t)*8)
102 * The radix can be up to x BLIST_BMAP_RADIX the largest skip,
103 * based on the initial skip calculation in blist_create().
105 * The radix will exceed the size of a 32 bit signed (or unsigned) int
106 * when the maximal number of blocks is allocated. This corresponds
107 * to ~1G x PAGE_SIZE = 4096GB. The swap code usually divides this
108 * by 4, leaving us with a capability of up to four 1TB swap devices.
110 #define BLIST_MAXBLKS (0x40000000 / \
111 (BLIST_BMAP_RADIX / BLIST_META_RADIX))
113 #define BLIST_MAX_ALLOC BLIST_BMAP_RADIX
115 extern blist_t blist_create(swblk_t blocks);
116 extern void blist_destroy(blist_t blist);
117 extern swblk_t blist_alloc(blist_t blist, swblk_t count);
118 extern void blist_free(blist_t blist, swblk_t blkno, swblk_t count);
119 extern void blist_print(blist_t blist);
120 extern void blist_resize(blist_t *pblist, swblk_t count, int freenew);
122 #endif /* _SYS_BLIST_H_ */