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 void 45 hammer_cache_set(int bytes) 46 { 47 CacheMax = bytes; 48 } 49 50 void 51 hammer_cache_add(struct cache_info *cache) 52 { 53 TAILQ_INSERT_HEAD(&CacheList, cache, entry); 54 CacheUse += HAMMER_BUFSIZE; 55 ++NCache; 56 } 57 58 void 59 hammer_cache_del(struct cache_info *cache) 60 { 61 TAILQ_REMOVE(&CacheList, cache, entry); 62 CacheUse -= HAMMER_BUFSIZE; 63 --NCache; 64 } 65 66 void 67 hammer_cache_used(struct cache_info *cache) 68 { 69 TAILQ_REMOVE(&CacheList, cache, entry); 70 TAILQ_INSERT_TAIL(&CacheList, cache, entry); 71 } 72 73 void 74 hammer_cache_flush(void) 75 { 76 struct cache_info *cache; 77 struct cache_info *p = NULL; 78 int target; 79 int count = 0; 80 81 if (CacheUse >= CacheMax) { 82 target = CacheMax / 2; 83 while ((cache = TAILQ_FIRST(&CacheList)) != NULL) { 84 if (cache == p) 85 break; /* seen this before */ 86 ++count; 87 if (cache->refs) { 88 if (p == NULL) 89 p = cache; 90 hammer_cache_used(cache); 91 continue; 92 } 93 if (count >= NCache) { 94 CacheMax += 8 * 1024 * 1024; 95 target = CacheMax / 2; 96 count = 1; 97 } 98 cache->refs = 1; 99 cache->delete = 1; 100 --count; 101 rel_buffer(cache->buffer); 102 103 if (CacheUse < target) 104 break; 105 } 106 } 107 } 108 109