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 = HAMMER_BUFSIZE * 1024;
  41 static TAILQ_HEAD(, cache_info) CacheList = TAILQ_HEAD_INITIALIZER(CacheList);
  42
  43 int
  44 hammer_parse_cache_size(const char *arg)
  45 {
  46         char *ptr;
  47         int size = strtol(arg, &ptr, 0);
  48
  49         switch(*ptr) {
  50         case 'm':
  51         case 'M':
  52                 size *= 1024;
  53                 /* fall through */
  54         case 'k':
  55         case 'K':
  56                 size *= 1024;
  57                 ++ptr;
  58                 break;
  59         case '\0':
  60         case ':':
  61                 /* bytes if no suffix */
  62                 break;
  63         default:
  64                 return(-1);
  65         }
  66
  67         if (*ptr == ':') {
  68                 UseReadAhead = strtol(ptr + 1, NULL, 0);
  69                 UseReadBehind = -UseReadAhead;
  70         }
  71         if (size < 1024 * 1024)
  72                 size = 1024 * 1024;
  73         if (UseReadAhead < 0)
  74                 return(-1);
  75         if (UseReadAhead * HAMMER_BUFSIZE / size / 16) {
  76                 UseReadAhead = size / 16 / HAMMER_BUFSIZE;
  77                 UseReadBehind = -UseReadAhead;
  78         }
  79
  80         CacheMax = size;
  81         return(0);
  82 }
  83
  84 void
  85 hammer_cache_add(struct cache_info *cache)
  86 {
  87         TAILQ_INSERT_HEAD(&CacheList, cache, entry);
  88         CacheUse += HAMMER_BUFSIZE;
  89 }
  90
  91 void
  92 hammer_cache_del(struct cache_info *cache)
  93 {
  94         TAILQ_REMOVE(&CacheList, cache, entry);
  95         CacheUse -= HAMMER_BUFSIZE;
  96 }
  97
  98 void
  99 hammer_cache_used(struct cache_info *cache)
 100 {
 101         TAILQ_REMOVE(&CacheList, cache, entry);
 102         TAILQ_INSERT_TAIL(&CacheList, cache, entry);
 103 }
 104
 105 void
 106 hammer_cache_flush(void)
 107 {
 108         struct cache_info *cache;
 109         struct cache_info *first = NULL;
 110         int count = 0;
 111
 112         if (CacheUse >= CacheMax)
 113                 while ((cache = TAILQ_FIRST(&CacheList)) != NULL) {
 114                         if (cache == first)
 115                                 break; /* seen this ref'd before */
 116
 117                         if (cache->refs) {
 118                                 if (first == NULL)
 119                                         first = cache;
 120                                 hammer_cache_used(cache);
 121                                 count++;
 122                                 continue;
 123                         }
 124                         if (count >= (CacheUse / HAMMER_BUFSIZE)) {
 125                                 CacheMax += HAMMER_BUFSIZE * 512;
 126                                 count = 0;
 127                         }
 128
 129                         cache->refs = 1;
 130                         cache->delete = 1;
 131                         rel_buffer((struct buffer_info*)cache);
 132
 133                         if (CacheUse < CacheMax / 2)
 134                                 break;
 135                 }
 136 }
 137