sys/sys/blist.h

   1 /*
   2  * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  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
  16  *    distribution.
  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.
  20  *
  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
  32  * SUCH DAMAGE.
  33  *
  34  * Implements bitmap resource lists.
  35  *
  36  *      Usage:
  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)
  43  *
  44  *
  45  *      Notes:
  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()
  49  *              ops.
  50  *
  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.
  56  *
  57  * $FreeBSD: src/sys/sys/blist.h,v 1.2.2.1 2003/01/12 09:23:12 dillon Exp $
  58  * $DragonFly: src/sys/sys/blist.h,v 1.7 2008/08/10 22:09:51 dillon Exp $
  59  */
  60
  61 #ifndef _SYS_BLIST_H_
  62 #define _SYS_BLIST_H_
  63
  64 #ifndef _SYS_TYPES_H_
  65 #include <sys/types.h>
  66 #endif
  67
  68 #define SWBLK_BITS      64
  69 typedef int64_t         swblk_t;
  70 typedef u_int64_t       u_swblk_t;
  71
  72 /*
  73  * note: currently use SWAPBLK_NONE as an absolute value rather then
  74  * a flag bit.
  75  */
  76 #define SWAPBLK_MASK    ((swblk_t)((u_swblk_t)-1 >> 1))         /* mask */
  77 #define SWAPBLK_NONE    ((swblk_t)((u_swblk_t)SWAPBLK_MASK + 1))/* flag */
  78
  79 /*
  80  * blmeta and bl_bitmap_t MUST be a power of 2 in size.
  81  */
  82
  83 typedef struct blmeta {
  84         union {
  85             swblk_t     bmu_avail;      /* space available under us     */
  86             u_swblk_t   bmu_bitmap;     /* bitmap if we are a leaf      */
  87         } u;
  88         swblk_t         bm_bighint;     /* biggest contiguous block hint*/
  89 } blmeta_t;
  90
  91 typedef struct blist {
  92         swblk_t         bl_blocks;      /* area of coverage             */
  93         int64_t         bl_radix;       /* coverage radix               */
  94         swblk_t         bl_skip;        /* starting skip                */
  95         swblk_t         bl_free;        /* number of free blocks        */
  96         blmeta_t        *bl_root;       /* root of radix tree           */
  97         swblk_t         bl_rootblks;    /* swblk_t blks allocated for tree */
  98 } *blist_t;
  99
 100 #define BLIST_META_RADIX        (sizeof(u_swblk_t)*8/2) /* 2 bits per */
 101 #define BLIST_BMAP_RADIX        (sizeof(u_swblk_t)*8)   /* 1 bit per */
 102
 103 /*
 104  * The radix may exceed the size of a 64 bit signed (or unsigned) int
 105  * when the maximal number of blocks is allocated.  With a 32-bit swblk_t
 106  * this corresponds to ~1G x PAGE_SIZE = 4096GB.  The swap code usually
 107  * divides this by 4, leaving us with a capability of up to four 1TB swap
 108  * devices.
 109  *
 110  * With a 64-bit swblk_t the limitation is some insane number.
 111  *
 112  * NOTE: For now I don't trust that we overflow-detect properly so we divide
 113  *       out to ensure that no overflow occurs.
 114  */
 115
 116 #if SWBLK_BITS == 64
 117 #define BLIST_MAXBLKS           (0x4000000000000000LL /         \
 118                                  (BLIST_BMAP_RADIX / BLIST_META_RADIX))
 119 #else
 120 #define BLIST_MAXBLKS           (0x40000000 /           \
 121                                  (BLIST_BMAP_RADIX / BLIST_META_RADIX))
 122 #endif
 123
 124 #define BLIST_MAX_ALLOC         BLIST_BMAP_RADIX
 125
 126 extern blist_t blist_create(swblk_t blocks);
 127 extern void blist_destroy(blist_t blist);
 128 extern swblk_t blist_alloc(blist_t blist, swblk_t count);
 129 extern swblk_t blist_allocat(blist_t blist, swblk_t count, swblk_t blkat);
 130 extern void blist_free(blist_t blist, swblk_t blkno, swblk_t count);
 131 extern swblk_t blist_fill(blist_t blist, swblk_t blkno, swblk_t count);
 132 extern void blist_print(blist_t blist);
 133 extern void blist_resize(blist_t *pblist, swblk_t count, int freenew);
 134
 135 #endif  /* _SYS_BLIST_H_ */