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  *              (void)  blist_resize(&blist, count, freeextra)
  42  *
  43  *
  44  *      Notes:
  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()
  48  *              ops.
  49  *
  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.
  55  *
  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 $
  58  */
  59
  60 #ifndef _SYS_BLIST_H_
  61 #define _SYS_BLIST_H_
  62
  63 #ifndef _SYS_TYPES_H_
  64 #include <sys/types.h>
  65 #endif
  66
  67 typedef int32_t         swblk_t;
  68 typedef u_int32_t       u_swblk_t;
  69
  70 /*
  71  * blmeta and bl_bitmap_t MUST be a power of 2 in size.
  72  */
  73
  74 typedef struct blmeta {
  75         union {
  76             swblk_t     bmu_avail;      /* space available under us     */
  77             u_swblk_t   bmu_bitmap;     /* bitmap if we are a leaf      */
  78         } u;
  79         swblk_t         bm_bighint;     /* biggest contiguous block hint*/
  80 } blmeta_t;
  81
  82 typedef struct blist {
  83         swblk_t         bl_blocks;      /* area of coverage             */
  84         int64_t         bl_radix;       /* coverage radix               */
  85         swblk_t         bl_skip;        /* starting skip                */
  86         swblk_t         bl_free;        /* number of free blocks        */
  87         blmeta_t        *bl_root;       /* root of radix tree           */
  88         swblk_t         bl_rootblks;    /* swblk_t blks allocated for tree */
  89 } *blist_t;
  90
  91 #define BLIST_META_RADIX        16
  92 #define BLIST_BMAP_RADIX        (sizeof(u_swblk_t)*8)
  93
  94 /*
  95  * The radix can be up to x BLIST_BMAP_RADIX the largest skip,
  96  * based on the initial skip calculation in blist_create().
  97  *
  98  * The radix will exceed the size of a 32 bit signed (or unsigned) int
  99  * when the maximal number of blocks is allocated.  This corresponds
 100  * to ~1G x PAGE_SIZE = 4096GB.  The swap code usually divides this
 101  * by 4, leaving us with a capability of up to four 1TB swap devices.
 102  */
 103 #define BLIST_MAXBLKS           (0x40000000 /           \
 104                                  (BLIST_BMAP_RADIX / BLIST_META_RADIX))
 105
 106 #define BLIST_MAX_ALLOC         BLIST_BMAP_RADIX
 107
 108 extern blist_t blist_create(swblk_t blocks);
 109 extern void blist_destroy(blist_t blist);
 110 extern swblk_t blist_alloc(blist_t blist, swblk_t count);
 111 extern void blist_free(blist_t blist, swblk_t blkno, swblk_t count);
 112 extern void blist_print(blist_t blist);
 113 extern void blist_resize(blist_t *pblist, swblk_t count, int freenew);
 114
 115 #endif  /* _SYS_BLIST_H_ */