1/*- 2 * See the file LICENSE for redistribution information. 3 * 4 * Copyright (c) 1996,2008 Oracle. All rights reserved. 5 * 6 * $Id: mp_trickle.c,v 12.20 2008/01/08 20:58:42 bostic Exp $ 7 */ 8 9#include "db_config.h" 10 11#include "db_int.h" 12#include "dbinc/log.h" 13#include "dbinc/mp.h" 14 15static int __memp_trickle __P((ENV *, int, int *)); 16 17/* 18 * __memp_trickle_pp -- 19 * ENV->memp_trickle pre/post processing. 20 * 21 * PUBLIC: int __memp_trickle_pp __P((DB_ENV *, int, int *)); 22 */ 23int 24__memp_trickle_pp(dbenv, pct, nwrotep) 25 DB_ENV *dbenv; 26 int pct, *nwrotep; 27{ 28 DB_THREAD_INFO *ip; 29 ENV *env; 30 int ret; 31 32 env = dbenv->env; 33 34 ENV_REQUIRES_CONFIG(env, 35 env->mp_handle, "memp_trickle", DB_INIT_MPOOL); 36 37 ENV_ENTER(env, ip); 38 REPLICATION_WRAP(env, (__memp_trickle(env, pct, nwrotep)), 0, ret); 39 ENV_LEAVE(env, ip); 40 return (ret); 41} 42 43/* 44 * __memp_trickle -- 45 * ENV->memp_trickle. 46 */ 47static int 48__memp_trickle(env, pct, nwrotep) 49 ENV *env; 50 int pct, *nwrotep; 51{ 52 DB_MPOOL *dbmp; 53 MPOOL *c_mp, *mp; 54 u_int32_t clean, dirty, i, need_clean, total, dtmp, wrote; 55 int ret; 56 57 dbmp = env->mp_handle; 58 mp = dbmp->reginfo[0].primary; 59 60 if (nwrotep != NULL) 61 *nwrotep = 0; 62 63 if (pct < 1 || pct > 100) { 64 __db_errx(env, 65 "DB_ENV->memp_trickle: %d: percent must be between 1 and 100", 66 pct); 67 return (EINVAL); 68 } 69 70 /* 71 * Loop through the caches counting total/dirty buffers. 72 * 73 * XXX 74 * Using hash_page_dirty is our only choice at the moment, but it's not 75 * as correct as we might like in the presence of pools having more 76 * than one page size, as a free 512B buffer may not be equivalent to 77 * having a free 8KB buffer. 78 */ 79 for (ret = 0, i = dirty = total = 0; i < mp->nreg; ++i) { 80 c_mp = dbmp->reginfo[i].primary; 81 total += c_mp->stat.st_pages; 82 __memp_stat_hash(&dbmp->reginfo[i], c_mp, &dtmp); 83 dirty += dtmp; 84 } 85 86 /* 87 * If there are sufficient clean buffers, no buffers or no dirty 88 * buffers, we're done. 89 */ 90 if (total == 0 || dirty == 0) 91 return (0); 92 93 /* 94 * The total number of pages is an exact number, but the dirty page 95 * count can change while we're walking the hash buckets, and it's 96 * even possible the dirty page count ends up larger than the total 97 * number of pages. 98 */ 99 clean = total > dirty ? total - dirty : 0; 100 need_clean = (total * (u_int)pct) / 100; 101 if (clean >= need_clean) 102 return (0); 103 104 need_clean -= clean; 105 ret = __memp_sync_int(env, NULL, 106 need_clean, DB_SYNC_TRICKLE | DB_SYNC_INTERRUPT_OK, &wrote, NULL); 107 STAT((mp->stat.st_page_trickle += wrote)); 108 if (nwrotep != NULL) 109 *nwrotep = (int)wrote; 110 111 return (ret); 112} 113