1fa9e4066Sahrens /* 2fa9e4066Sahrens * CDDL HEADER START 3fa9e4066Sahrens * 4fa9e4066Sahrens * The contents of this file are subject to the terms of the 5ea8dc4b6Seschrock * Common Development and Distribution License (the "License"). 6ea8dc4b6Seschrock * You may not use this file except in compliance with the License. 7fa9e4066Sahrens * 8fa9e4066Sahrens * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9fa9e4066Sahrens * or http://www.opensolaris.org/os/licensing. 10fa9e4066Sahrens * See the License for the specific language governing permissions 11fa9e4066Sahrens * and limitations under the License. 12fa9e4066Sahrens * 13fa9e4066Sahrens * When distributing Covered Code, include this CDDL HEADER in each 14fa9e4066Sahrens * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15fa9e4066Sahrens * If applicable, add the following below this CDDL HEADER, with the 16fa9e4066Sahrens * fields enclosed by brackets "[]" replaced with your own identifying 17fa9e4066Sahrens * information: Portions Copyright [yyyy] [name of copyright owner] 18fa9e4066Sahrens * 19fa9e4066Sahrens * CDDL HEADER END 20fa9e4066Sahrens */ 21fa9e4066Sahrens /* 2287db74c1Sek * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 23fa9e4066Sahrens * Use is subject to license terms. 24fa9e4066Sahrens */ 25fa9e4066Sahrens 26fa9e4066Sahrens #include <sys/zfs_context.h> 27fa9e4066Sahrens #include <sys/spa.h> 28fa9e4066Sahrens #include <sys/vdev_impl.h> 29fa9e4066Sahrens #include <sys/zio.h> 3087db74c1Sek #include <sys/kstat.h> 31fa9e4066Sahrens 32fa9e4066Sahrens /* 33fa9e4066Sahrens * Virtual device read-ahead caching. 34fa9e4066Sahrens * 35fa9e4066Sahrens * This file implements a simple LRU read-ahead cache. When the DMU reads 36fa9e4066Sahrens * a given block, it will often want other, nearby blocks soon thereafter. 37fa9e4066Sahrens * We take advantage of this by reading a larger disk region and caching 3887db74c1Sek * the result. In the best case, this can turn 128 back-to-back 512-byte 3987db74c1Sek * reads into a single 64k read followed by 127 cache hits; this reduces 40fa9e4066Sahrens * latency dramatically. In the worst case, it can turn an isolated 512-byte 4187db74c1Sek * read into a 64k read, which doesn't affect latency all that much but is 42fa9e4066Sahrens * terribly wasteful of bandwidth. A more intelligent version of the cache 43fa9e4066Sahrens * could keep track of access patterns and not do read-ahead unless it sees 44fdb2e906Sek * at least two temporally close I/Os to the same region. Currently, only 45fdb2e906Sek * metadata I/O is inflated. A futher enhancement could take advantage of 46fdb2e906Sek * more semantic information about the I/O. And it could use something 47fdb2e906Sek * faster than an AVL tree; that was chosen solely for convenience. 48fa9e4066Sahrens * 49fa9e4066Sahrens * There are five cache operations: allocate, fill, read, write, evict. 50fa9e4066Sahrens * 51fa9e4066Sahrens * (1) Allocate. This reserves a cache entry for the specified region. 52fa9e4066Sahrens * We separate the allocate and fill operations so that multiple threads 53fa9e4066Sahrens * don't generate I/O for the same cache miss. 54fa9e4066Sahrens * 55fa9e4066Sahrens * (2) Fill. When the I/O for a cache miss completes, the fill routine 56fa9e4066Sahrens * places the data in the previously allocated cache entry. 57fa9e4066Sahrens * 58fa9e4066Sahrens * (3) Read. Read data from the cache. 59fa9e4066Sahrens * 60fa9e4066Sahrens * (4) Write. Update cache contents after write completion. 61fa9e4066Sahrens * 62fa9e4066Sahrens * (5) Evict. When allocating a new entry, we evict the oldest (LRU) entry 63614409b5Sahrens * if the total cache size exceeds zfs_vdev_cache_size. 64fa9e4066Sahrens */ 65fa9e4066Sahrens 66614409b5Sahrens /* 67614409b5Sahrens * These tunables are for performance analysis. 68614409b5Sahrens */ 69614409b5Sahrens /* 70614409b5Sahrens * All i/os smaller than zfs_vdev_cache_max will be turned into 71614409b5Sahrens * 1<<zfs_vdev_cache_bshift byte reads by the vdev_cache (aka software 7287db74c1Sek * track buffer). At most zfs_vdev_cache_size bytes will be kept in each 73614409b5Sahrens * vdev's vdev_cache. 74614409b5Sahrens */ 7587db74c1Sek int zfs_vdev_cache_max = 1<<14; /* 16KB */ 7687db74c1Sek int zfs_vdev_cache_size = 10ULL << 20; /* 10MB */ 77614409b5Sahrens int zfs_vdev_cache_bshift = 16; 78614409b5Sahrens 7987db74c1Sek #define VCBS (1 << zfs_vdev_cache_bshift) /* 64KB */ 8087db74c1Sek 8187db74c1Sek kstat_t *vdc_ksp = NULL; 8287db74c1Sek 8387db74c1Sek typedef struct vdc_stats { 8487db74c1Sek kstat_named_t vdc_stat_delegations; 8587db74c1Sek kstat_named_t vdc_stat_hits; 8687db74c1Sek kstat_named_t vdc_stat_misses; 8787db74c1Sek } vdc_stats_t; 8887db74c1Sek 8987db74c1Sek static vdc_stats_t vdc_stats = { 9087db74c1Sek { "delegations", KSTAT_DATA_UINT64 }, 9187db74c1Sek { "hits", KSTAT_DATA_UINT64 }, 9287db74c1Sek { "misses", KSTAT_DATA_UINT64 } 9387db74c1Sek }; 9487db74c1Sek 9587db74c1Sek #define VDCSTAT_BUMP(stat) atomic_add_64(&vdc_stats.stat.value.ui64, 1); 96614409b5Sahrens 97fa9e4066Sahrens static int 98fa9e4066Sahrens vdev_cache_offset_compare(const void *a1, const void *a2) 99fa9e4066Sahrens { 100fa9e4066Sahrens const vdev_cache_entry_t *ve1 = a1; 101fa9e4066Sahrens const vdev_cache_entry_t *ve2 = a2; 102fa9e4066Sahrens 103fa9e4066Sahrens if (ve1->ve_offset < ve2->ve_offset) 104fa9e4066Sahrens return (-1); 105fa9e4066Sahrens if (ve1->ve_offset > ve2->ve_offset) 106fa9e4066Sahrens return (1); 107fa9e4066Sahrens return (0); 108fa9e4066Sahrens } 109fa9e4066Sahrens 110fa9e4066Sahrens static int 111fa9e4066Sahrens vdev_cache_lastused_compare(const void *a1, const void *a2) 112fa9e4066Sahrens { 113fa9e4066Sahrens const vdev_cache_entry_t *ve1 = a1; 114fa9e4066Sahrens const vdev_cache_entry_t *ve2 = a2; 115fa9e4066Sahrens 116fa9e4066Sahrens if (ve1->ve_lastused < ve2->ve_lastused) 117fa9e4066Sahrens return (-1); 118fa9e4066Sahrens if (ve1->ve_lastused > ve2->ve_lastused) 119fa9e4066Sahrens return (1); 120fa9e4066Sahrens 121fa9e4066Sahrens /* 122fa9e4066Sahrens * Among equally old entries, sort by offset to ensure uniqueness. 123fa9e4066Sahrens */ 124fa9e4066Sahrens return (vdev_cache_offset_compare(a1, a2)); 125fa9e4066Sahrens } 126fa9e4066Sahrens 127fa9e4066Sahrens /* 128fa9e4066Sahrens * Evict the specified entry from the cache. 129fa9e4066Sahrens */ 130fa9e4066Sahrens static void 131fa9e4066Sahrens vdev_cache_evict(vdev_cache_t *vc, vdev_cache_entry_t *ve) 132fa9e4066Sahrens { 133fa9e4066Sahrens ASSERT(MUTEX_HELD(&vc->vc_lock)); 134fa9e4066Sahrens ASSERT(ve->ve_fill_io == NULL); 135fa9e4066Sahrens ASSERT(ve->ve_data != NULL); 136fa9e4066Sahrens 137fa9e4066Sahrens avl_remove(&vc->vc_lastused_tree, ve); 138fa9e4066Sahrens avl_remove(&vc->vc_offset_tree, ve); 139614409b5Sahrens zio_buf_free(ve->ve_data, VCBS); 140fa9e4066Sahrens kmem_free(ve, sizeof (vdev_cache_entry_t)); 141fa9e4066Sahrens } 142fa9e4066Sahrens 143fa9e4066Sahrens /* 144fa9e4066Sahrens * Allocate an entry in the cache. At the point we don't have the data, 145fa9e4066Sahrens * we're just creating a placeholder so that multiple threads don't all 146fa9e4066Sahrens * go off and read the same blocks. 147fa9e4066Sahrens */ 148fa9e4066Sahrens static vdev_cache_entry_t * 149fa9e4066Sahrens vdev_cache_allocate(zio_t *zio) 150fa9e4066Sahrens { 151fa9e4066Sahrens vdev_cache_t *vc = &zio->io_vd->vdev_cache; 152614409b5Sahrens uint64_t offset = P2ALIGN(zio->io_offset, VCBS); 153fa9e4066Sahrens vdev_cache_entry_t *ve; 154fa9e4066Sahrens 155fa9e4066Sahrens ASSERT(MUTEX_HELD(&vc->vc_lock)); 156fa9e4066Sahrens 157614409b5Sahrens if (zfs_vdev_cache_size == 0) 158fa9e4066Sahrens return (NULL); 159fa9e4066Sahrens 160fa9e4066Sahrens /* 161fa9e4066Sahrens * If adding a new entry would exceed the cache size, 162fa9e4066Sahrens * evict the oldest entry (LRU). 163fa9e4066Sahrens */ 164614409b5Sahrens if ((avl_numnodes(&vc->vc_lastused_tree) << zfs_vdev_cache_bshift) > 165614409b5Sahrens zfs_vdev_cache_size) { 166fa9e4066Sahrens ve = avl_first(&vc->vc_lastused_tree); 167*e14bb325SJeff Bonwick if (ve->ve_fill_io != NULL) 168fa9e4066Sahrens return (NULL); 169fa9e4066Sahrens ASSERT(ve->ve_hits != 0); 170fa9e4066Sahrens vdev_cache_evict(vc, ve); 171fa9e4066Sahrens } 172fa9e4066Sahrens 173fa9e4066Sahrens ve = kmem_zalloc(sizeof (vdev_cache_entry_t), KM_SLEEP); 174fa9e4066Sahrens ve->ve_offset = offset; 175fa9e4066Sahrens ve->ve_lastused = lbolt; 176614409b5Sahrens ve->ve_data = zio_buf_alloc(VCBS); 177fa9e4066Sahrens 178fa9e4066Sahrens avl_add(&vc->vc_offset_tree, ve); 179fa9e4066Sahrens avl_add(&vc->vc_lastused_tree, ve); 180fa9e4066Sahrens 181fa9e4066Sahrens return (ve); 182fa9e4066Sahrens } 183fa9e4066Sahrens 184fa9e4066Sahrens static void 185fa9e4066Sahrens vdev_cache_hit(vdev_cache_t *vc, vdev_cache_entry_t *ve, zio_t *zio) 186fa9e4066Sahrens { 187614409b5Sahrens uint64_t cache_phase = P2PHASE(zio->io_offset, VCBS); 188fa9e4066Sahrens 189fa9e4066Sahrens ASSERT(MUTEX_HELD(&vc->vc_lock)); 190fa9e4066Sahrens ASSERT(ve->ve_fill_io == NULL); 191fa9e4066Sahrens 192fa9e4066Sahrens if (ve->ve_lastused != lbolt) { 193fa9e4066Sahrens avl_remove(&vc->vc_lastused_tree, ve); 194fa9e4066Sahrens ve->ve_lastused = lbolt; 195fa9e4066Sahrens avl_add(&vc->vc_lastused_tree, ve); 196fa9e4066Sahrens } 197fa9e4066Sahrens 198fa9e4066Sahrens ve->ve_hits++; 199fa9e4066Sahrens bcopy(ve->ve_data + cache_phase, zio->io_data, zio->io_size); 200fa9e4066Sahrens } 201fa9e4066Sahrens 202fa9e4066Sahrens /* 203fa9e4066Sahrens * Fill a previously allocated cache entry with data. 204fa9e4066Sahrens */ 205fa9e4066Sahrens static void 206fa9e4066Sahrens vdev_cache_fill(zio_t *zio) 207fa9e4066Sahrens { 208fa9e4066Sahrens vdev_t *vd = zio->io_vd; 209fa9e4066Sahrens vdev_cache_t *vc = &vd->vdev_cache; 210fa9e4066Sahrens vdev_cache_entry_t *ve = zio->io_private; 211fa9e4066Sahrens zio_t *dio; 212fa9e4066Sahrens 213614409b5Sahrens ASSERT(zio->io_size == VCBS); 214fa9e4066Sahrens 215fa9e4066Sahrens /* 216fa9e4066Sahrens * Add data to the cache. 217fa9e4066Sahrens */ 218fa9e4066Sahrens mutex_enter(&vc->vc_lock); 219fa9e4066Sahrens 220fa9e4066Sahrens ASSERT(ve->ve_fill_io == zio); 221fa9e4066Sahrens ASSERT(ve->ve_offset == zio->io_offset); 222fa9e4066Sahrens ASSERT(ve->ve_data == zio->io_data); 223fa9e4066Sahrens 224fa9e4066Sahrens ve->ve_fill_io = NULL; 225fa9e4066Sahrens 226fa9e4066Sahrens /* 227fa9e4066Sahrens * Even if this cache line was invalidated by a missed write update, 228fa9e4066Sahrens * any reads that were queued up before the missed update are still 229fa9e4066Sahrens * valid, so we can satisfy them from this line before we evict it. 230fa9e4066Sahrens */ 231fa9e4066Sahrens for (dio = zio->io_delegate_list; dio; dio = dio->io_delegate_next) 232fa9e4066Sahrens vdev_cache_hit(vc, ve, dio); 233fa9e4066Sahrens 234fa9e4066Sahrens if (zio->io_error || ve->ve_missed_update) 235fa9e4066Sahrens vdev_cache_evict(vc, ve); 236fa9e4066Sahrens 237fa9e4066Sahrens mutex_exit(&vc->vc_lock); 238fa9e4066Sahrens 239fa9e4066Sahrens while ((dio = zio->io_delegate_list) != NULL) { 240fa9e4066Sahrens zio->io_delegate_list = dio->io_delegate_next; 241fa9e4066Sahrens dio->io_delegate_next = NULL; 242fa9e4066Sahrens dio->io_error = zio->io_error; 243e05725b1Sbonwick zio_execute(dio); 244fa9e4066Sahrens } 245fa9e4066Sahrens } 246fa9e4066Sahrens 247fa9e4066Sahrens /* 248fa9e4066Sahrens * Read data from the cache. Returns 0 on cache hit, errno on a miss. 249fa9e4066Sahrens */ 250fa9e4066Sahrens int 251fa9e4066Sahrens vdev_cache_read(zio_t *zio) 252fa9e4066Sahrens { 253fa9e4066Sahrens vdev_cache_t *vc = &zio->io_vd->vdev_cache; 254fa9e4066Sahrens vdev_cache_entry_t *ve, ve_search; 255614409b5Sahrens uint64_t cache_offset = P2ALIGN(zio->io_offset, VCBS); 256614409b5Sahrens uint64_t cache_phase = P2PHASE(zio->io_offset, VCBS); 257fa9e4066Sahrens zio_t *fio; 258fa9e4066Sahrens 259fa9e4066Sahrens ASSERT(zio->io_type == ZIO_TYPE_READ); 260fa9e4066Sahrens 261fa9e4066Sahrens if (zio->io_flags & ZIO_FLAG_DONT_CACHE) 262fa9e4066Sahrens return (EINVAL); 263fa9e4066Sahrens 264614409b5Sahrens if (zio->io_size > zfs_vdev_cache_max) 265fa9e4066Sahrens return (EOVERFLOW); 266fa9e4066Sahrens 267fa9e4066Sahrens /* 268fa9e4066Sahrens * If the I/O straddles two or more cache blocks, don't cache it. 269fa9e4066Sahrens */ 270614409b5Sahrens if (P2CROSS(zio->io_offset, zio->io_offset + zio->io_size - 1, VCBS)) 271fa9e4066Sahrens return (EXDEV); 272fa9e4066Sahrens 273614409b5Sahrens ASSERT(cache_phase + zio->io_size <= VCBS); 274fa9e4066Sahrens 275fa9e4066Sahrens mutex_enter(&vc->vc_lock); 276fa9e4066Sahrens 277fa9e4066Sahrens ve_search.ve_offset = cache_offset; 278fa9e4066Sahrens ve = avl_find(&vc->vc_offset_tree, &ve_search, NULL); 279fa9e4066Sahrens 280fa9e4066Sahrens if (ve != NULL) { 281fa9e4066Sahrens if (ve->ve_missed_update) { 282fa9e4066Sahrens mutex_exit(&vc->vc_lock); 283fa9e4066Sahrens return (ESTALE); 284fa9e4066Sahrens } 285fa9e4066Sahrens 286fa9e4066Sahrens if ((fio = ve->ve_fill_io) != NULL) { 287fa9e4066Sahrens zio->io_delegate_next = fio->io_delegate_list; 288fa9e4066Sahrens fio->io_delegate_list = zio; 289fa9e4066Sahrens zio_vdev_io_bypass(zio); 290fa9e4066Sahrens mutex_exit(&vc->vc_lock); 29187db74c1Sek VDCSTAT_BUMP(vdc_stat_delegations); 292fa9e4066Sahrens return (0); 293fa9e4066Sahrens } 294fa9e4066Sahrens 295fa9e4066Sahrens vdev_cache_hit(vc, ve, zio); 296fa9e4066Sahrens zio_vdev_io_bypass(zio); 297fa9e4066Sahrens 298fa9e4066Sahrens mutex_exit(&vc->vc_lock); 299e05725b1Sbonwick zio_execute(zio); 30087db74c1Sek VDCSTAT_BUMP(vdc_stat_hits); 301fa9e4066Sahrens return (0); 302fa9e4066Sahrens } 303fa9e4066Sahrens 304fa9e4066Sahrens ve = vdev_cache_allocate(zio); 305fa9e4066Sahrens 306fa9e4066Sahrens if (ve == NULL) { 307fa9e4066Sahrens mutex_exit(&vc->vc_lock); 308fa9e4066Sahrens return (ENOMEM); 309fa9e4066Sahrens } 310fa9e4066Sahrens 311*e14bb325SJeff Bonwick fio = zio_vdev_delegated_io(zio->io_vd, cache_offset, 312614409b5Sahrens ve->ve_data, VCBS, ZIO_TYPE_READ, ZIO_PRIORITY_CACHE_FILL, 313*e14bb325SJeff Bonwick ZIO_FLAG_DONT_CACHE, vdev_cache_fill, ve); 314fa9e4066Sahrens 315fa9e4066Sahrens ve->ve_fill_io = fio; 316fa9e4066Sahrens fio->io_delegate_list = zio; 317fa9e4066Sahrens zio_vdev_io_bypass(zio); 318fa9e4066Sahrens 319fa9e4066Sahrens mutex_exit(&vc->vc_lock); 320fa9e4066Sahrens zio_nowait(fio); 32187db74c1Sek VDCSTAT_BUMP(vdc_stat_misses); 322fa9e4066Sahrens 323fa9e4066Sahrens return (0); 324fa9e4066Sahrens } 325fa9e4066Sahrens 326fa9e4066Sahrens /* 327fa9e4066Sahrens * Update cache contents upon write completion. 328fa9e4066Sahrens */ 329fa9e4066Sahrens void 330fa9e4066Sahrens vdev_cache_write(zio_t *zio) 331fa9e4066Sahrens { 332fa9e4066Sahrens vdev_cache_t *vc = &zio->io_vd->vdev_cache; 333fa9e4066Sahrens vdev_cache_entry_t *ve, ve_search; 334fa9e4066Sahrens uint64_t io_start = zio->io_offset; 335fa9e4066Sahrens uint64_t io_end = io_start + zio->io_size; 336614409b5Sahrens uint64_t min_offset = P2ALIGN(io_start, VCBS); 337614409b5Sahrens uint64_t max_offset = P2ROUNDUP(io_end, VCBS); 338fa9e4066Sahrens avl_index_t where; 339fa9e4066Sahrens 340fa9e4066Sahrens ASSERT(zio->io_type == ZIO_TYPE_WRITE); 341fa9e4066Sahrens 342fa9e4066Sahrens mutex_enter(&vc->vc_lock); 343fa9e4066Sahrens 344fa9e4066Sahrens ve_search.ve_offset = min_offset; 345fa9e4066Sahrens ve = avl_find(&vc->vc_offset_tree, &ve_search, &where); 346fa9e4066Sahrens 347fa9e4066Sahrens if (ve == NULL) 348fa9e4066Sahrens ve = avl_nearest(&vc->vc_offset_tree, where, AVL_AFTER); 349fa9e4066Sahrens 350fa9e4066Sahrens while (ve != NULL && ve->ve_offset < max_offset) { 351fa9e4066Sahrens uint64_t start = MAX(ve->ve_offset, io_start); 352614409b5Sahrens uint64_t end = MIN(ve->ve_offset + VCBS, io_end); 353fa9e4066Sahrens 354fa9e4066Sahrens if (ve->ve_fill_io != NULL) { 355fa9e4066Sahrens ve->ve_missed_update = 1; 356fa9e4066Sahrens } else { 357fa9e4066Sahrens bcopy((char *)zio->io_data + start - io_start, 358fa9e4066Sahrens ve->ve_data + start - ve->ve_offset, end - start); 359fa9e4066Sahrens } 360fa9e4066Sahrens ve = AVL_NEXT(&vc->vc_offset_tree, ve); 361fa9e4066Sahrens } 362fa9e4066Sahrens mutex_exit(&vc->vc_lock); 363fa9e4066Sahrens } 364fa9e4066Sahrens 3653d7072f8Seschrock void 3663d7072f8Seschrock vdev_cache_purge(vdev_t *vd) 3673d7072f8Seschrock { 3683d7072f8Seschrock vdev_cache_t *vc = &vd->vdev_cache; 3693d7072f8Seschrock vdev_cache_entry_t *ve; 3703d7072f8Seschrock 3713d7072f8Seschrock mutex_enter(&vc->vc_lock); 3723d7072f8Seschrock while ((ve = avl_first(&vc->vc_offset_tree)) != NULL) 3733d7072f8Seschrock vdev_cache_evict(vc, ve); 3743d7072f8Seschrock mutex_exit(&vc->vc_lock); 3753d7072f8Seschrock } 3763d7072f8Seschrock 377fa9e4066Sahrens void 378fa9e4066Sahrens vdev_cache_init(vdev_t *vd) 379fa9e4066Sahrens { 380fa9e4066Sahrens vdev_cache_t *vc = &vd->vdev_cache; 381fa9e4066Sahrens 382fa9e4066Sahrens mutex_init(&vc->vc_lock, NULL, MUTEX_DEFAULT, NULL); 383fa9e4066Sahrens 384fa9e4066Sahrens avl_create(&vc->vc_offset_tree, vdev_cache_offset_compare, 385fa9e4066Sahrens sizeof (vdev_cache_entry_t), 386fa9e4066Sahrens offsetof(struct vdev_cache_entry, ve_offset_node)); 387fa9e4066Sahrens 388fa9e4066Sahrens avl_create(&vc->vc_lastused_tree, vdev_cache_lastused_compare, 389fa9e4066Sahrens sizeof (vdev_cache_entry_t), 390fa9e4066Sahrens offsetof(struct vdev_cache_entry, ve_lastused_node)); 391fa9e4066Sahrens } 392fa9e4066Sahrens 393fa9e4066Sahrens void 394fa9e4066Sahrens vdev_cache_fini(vdev_t *vd) 395fa9e4066Sahrens { 396fa9e4066Sahrens vdev_cache_t *vc = &vd->vdev_cache; 397fa9e4066Sahrens 3983d7072f8Seschrock vdev_cache_purge(vd); 399fa9e4066Sahrens 400fa9e4066Sahrens avl_destroy(&vc->vc_offset_tree); 401fa9e4066Sahrens avl_destroy(&vc->vc_lastused_tree); 402fa9e4066Sahrens 403fa9e4066Sahrens mutex_destroy(&vc->vc_lock); 404fa9e4066Sahrens } 40587db74c1Sek 40687db74c1Sek void 40787db74c1Sek vdev_cache_stat_init(void) 40887db74c1Sek { 40987db74c1Sek vdc_ksp = kstat_create("zfs", 0, "vdev_cache_stats", "misc", 41087db74c1Sek KSTAT_TYPE_NAMED, sizeof (vdc_stats) / sizeof (kstat_named_t), 41187db74c1Sek KSTAT_FLAG_VIRTUAL); 41287db74c1Sek if (vdc_ksp != NULL) { 41387db74c1Sek vdc_ksp->ks_data = &vdc_stats; 41487db74c1Sek kstat_install(vdc_ksp); 41587db74c1Sek } 41687db74c1Sek } 41787db74c1Sek 41887db74c1Sek void 41987db74c1Sek vdev_cache_stat_fini(void) 42087db74c1Sek { 42187db74c1Sek if (vdc_ksp != NULL) { 42287db74c1Sek kstat_delete(vdc_ksp); 42387db74c1Sek vdc_ksp = NULL; 42487db74c1Sek } 42587db74c1Sek } 426