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 * nblks = blist_fill(blist, blkno, count)
42 * (void) blist_resize(&blist, count, freeextra)
46 * on creation, the entire list is marked reserved. You should
47 * first blist_free() the sections you want to make available
48 * for allocation before doing general blist_alloc()/free()
51 * SWAPBLK_NONE is returned on failure. This module is typically
52 * capable of managing up to (2^31) blocks per blist, though
53 * the memory utilization would be insane if you actually did
54 * that. Managing something like 512MB worth of 4K blocks
55 * eats around 32 KBytes of memory.
57 * $FreeBSD: src/sys/sys/blist.h,v 1.2.2.1 2003/01/12 09:23:12 dillon Exp $
64 #include <sys/types.h>
68 typedef int64_t swblk_t;
69 typedef u_int64_t u_swblk_t;
72 * note: currently use SWAPBLK_NONE as an absolute value rather then
75 #define SWAPBLK_MASK ((swblk_t)((u_swblk_t)-1 >> 1)) /* mask */
76 #define SWAPBLK_NONE ((swblk_t)((u_swblk_t)SWAPBLK_MASK + 1))/* flag */
79 * blmeta and bl_bitmap_t MUST be a power of 2 in size.
82 typedef struct blmeta {
84 swblk_t bmu_avail; /* space available under us */
85 u_swblk_t bmu_bitmap; /* bitmap if we are a leaf */
87 swblk_t bm_bighint; /* biggest contiguous block hint*/
90 typedef struct blist {
91 swblk_t bl_blocks; /* area of coverage */
92 int64_t bl_radix; /* coverage radix */
93 swblk_t bl_skip; /* starting skip */
94 swblk_t bl_free; /* number of free blocks */
95 blmeta_t *bl_root; /* root of radix tree */
96 swblk_t bl_rootblks; /* swblk_t blks allocated for tree */
99 #define BLIST_META_RADIX (sizeof(u_swblk_t)*8/2) /* 2 bits per */
100 #define BLIST_BMAP_RADIX (sizeof(u_swblk_t)*8) /* 1 bit per */
103 * The radix may exceed the size of a 64 bit signed (or unsigned) int
104 * when the maximal number of blocks is allocated. With a 32-bit swblk_t
105 * this corresponds to ~1G x PAGE_SIZE = 4096GB. The swap code usually
106 * divides this by 4, leaving us with a capability of up to four 1TB swap
109 * With a 64-bit swblk_t the limitation is some insane number.
111 * NOTE: For now I don't trust that we overflow-detect properly so we divide
112 * out to ensure that no overflow occurs.
116 #define BLIST_MAXBLKS (0x4000000000000000LL / \
117 (BLIST_BMAP_RADIX / BLIST_META_RADIX))
119 #define BLIST_MAXBLKS (0x40000000 / \
120 (BLIST_BMAP_RADIX / BLIST_META_RADIX))
123 #define BLIST_MAX_ALLOC BLIST_BMAP_RADIX
125 blist_t blist_create(swblk_t);
126 void blist_destroy(blist_t);
127 swblk_t blist_alloc(blist_t, swblk_t);
128 swblk_t blist_allocat(blist_t, swblk_t, swblk_t);
129 void blist_free(blist_t, swblk_t, swblk_t);
130 swblk_t blist_fill(blist_t, swblk_t, swblk_t);
131 void blist_print(blist_t);
132 void blist_resize(blist_t *, swblk_t, int);
134 #endif /* _SYS_BLIST_H_ */