sbin/hammer/cache.c

   1 /*
   2  * Copyright (c) 2008 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  * $DragonFly: src/sbin/hammer/cache.c,v 1.5 2008/05/16 18:39:03 dillon Exp $
  35  */
  36
  37 #include "hammer_util.h"
  38
  39 static int CacheUse;
  40 static int CacheMax = 16 * 1024 * 1024;
  41 static int NCache;
  42 static TAILQ_HEAD(, cache_info) CacheList = TAILQ_HEAD_INITIALIZER(CacheList);
  43
  44 int
  45 hammer_parse_cache_size(const char *arg)
  46 {
  47         char *ptr;
  48         int size = strtol(arg, &ptr, 0);
  49
  50         switch(*ptr) {
  51         case 'm':
  52         case 'M':
  53                 size *= 1024;
  54                 /* fall through */
  55         case 'k':
  56         case 'K':
  57                 size *= 1024;
  58                 ++ptr;
  59                 break;
  60         case '\0':
  61         case ':':
  62                 /* bytes if no suffix */
  63                 break;
  64         default:
  65                 return(-1);
  66         }
  67
  68         if (*ptr == ':') {
  69                 UseReadAhead = strtol(ptr + 1, NULL, 0);
  70                 UseReadBehind = -UseReadAhead;
  71         }
  72         if (size < 1024 * 1024)
  73                 size = 1024 * 1024;
  74         if (UseReadAhead < 0)
  75                 return(-1);
  76         if (UseReadAhead * HAMMER_BUFSIZE / size / 16) {
  77                 UseReadAhead = size / 16 / HAMMER_BUFSIZE;
  78                 UseReadBehind = -UseReadAhead;
  79         }
  80
  81         CacheMax = size;
  82         return(0);
  83 }
  84
  85 void
  86 hammer_cache_add(struct cache_info *cache)
  87 {
  88         TAILQ_INSERT_HEAD(&CacheList, cache, entry);
  89         CacheUse += HAMMER_BUFSIZE;
  90         ++NCache;
  91 }
  92
  93 void
  94 hammer_cache_del(struct cache_info *cache)
  95 {
  96         TAILQ_REMOVE(&CacheList, cache, entry);
  97         CacheUse -= HAMMER_BUFSIZE;
  98         --NCache;
  99 }
 100
 101 void
 102 hammer_cache_used(struct cache_info *cache)
 103 {
 104         TAILQ_REMOVE(&CacheList, cache, entry);
 105         TAILQ_INSERT_TAIL(&CacheList, cache, entry);
 106 }
 107
 108 void
 109 hammer_cache_flush(void)
 110 {
 111         struct cache_info *cache;
 112         struct cache_info *p = NULL;
 113         int target;
 114         int count = 0;
 115
 116         if (CacheUse >= CacheMax) {
 117                 target = CacheMax / 2;
 118                 while ((cache = TAILQ_FIRST(&CacheList)) != NULL) {
 119                         if (cache == p)
 120                                 break;  /* seen this before */
 121                         ++count;
 122                         if (cache->refs) {
 123                                 if (p == NULL)
 124                                         p = cache;
 125                                 hammer_cache_used(cache);
 126                                 continue;
 127                         }
 128                         if (count >= NCache) {
 129                                 CacheMax += 8 * 1024 * 1024;
 130                                 target = CacheMax / 2;
 131                                 count = 1;
 132                         }
 133                         cache->refs = 1;
 134                         cache->delete = 1;
 135                         --count;
 136                         rel_buffer((struct buffer_info*)cache);
 137
 138                         if (CacheUse < target)
 139                                 break;
 140                 }
 141         }
 142 }
 143