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, enum cache_type type) 52 { 53 TAILQ_INSERT_HEAD(&CacheList, cache, entry); 54 cache->type = type; 55 CacheUse += HAMMER_BUFSIZE; 56 ++NCache; 57 } 58 59 void 60 hammer_cache_del(struct cache_info *cache) 61 { 62 TAILQ_REMOVE(&CacheList, cache, entry); 63 CacheUse -= HAMMER_BUFSIZE; 64 --NCache; 65 } 66 67 void 68 hammer_cache_used(struct cache_info *cache) 69 { 70 TAILQ_REMOVE(&CacheList, cache, entry); 71 TAILQ_INSERT_TAIL(&CacheList, cache, entry); 72 } 73 74 void 75 hammer_cache_flush(void) 76 { 77 struct cache_info *cache; 78 struct cache_info *p = NULL; 79 int target; 80 int count = 0; 81 int ncache = NCache; 82 83 if (CacheUse >= CacheMax) { 84 target = CacheMax / 2; 85 while ((cache = TAILQ_FIRST(&CacheList)) != NULL) { 86 if (cache == p) 87 break; /* seen this before */ 88 ++count; 89 if (cache->refs) { 90 if (p == NULL) 91 p = cache; 92 hammer_cache_used(cache); 93 continue; 94 } 95 if (count >= NCache) { 96 CacheMax += 8 * 1024 * 1024; 97 target = CacheMax / 2; 98 count = 1; 99 } 100 cache->refs = 1; 101 cache->delete = 1; 102 --count; 103 104 switch(cache->type) { 105 case ISVOLUME: 106 rel_volume(cache->u.volume); 107 break; 108 case ISBUFFER: 109 rel_buffer(cache->u.buffer); 110 break; 111 default: 112 errx(1, "hammer_cache_flush: unknown type: %d", 113 (int)cache->type); 114 /* not reached */ 115 break; 116 } 117 /* structure was freed */ 118 if (CacheUse < target) 119 break; 120 } 121 if (DebugOpt > 1) 122 fprintf(stderr, "hammer_cache_flush: free %d/%d cache\n", 123 ncache - NCache, ncache); 124 } 125 } 126 127