1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
| 1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
|
22 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
| 22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
|
23 * Use is subject to license terms.
24 */
25
26#include <sys/zfs_context.h>
27#include <sys/spa.h>
28#include <sys/vdev_impl.h>
29#include <sys/zio.h>
30#include <sys/kstat.h>
31
32/*
33 * Virtual device read-ahead caching.
34 *
35 * This file implements a simple LRU read-ahead cache. When the DMU reads
36 * a given block, it will often want other, nearby blocks soon thereafter.
37 * We take advantage of this by reading a larger disk region and caching
38 * the result. In the best case, this can turn 128 back-to-back 512-byte
39 * reads into a single 64k read followed by 127 cache hits; this reduces
40 * latency dramatically. In the worst case, it can turn an isolated 512-byte
41 * read into a 64k read, which doesn't affect latency all that much but is
42 * terribly wasteful of bandwidth. A more intelligent version of the cache
43 * could keep track of access patterns and not do read-ahead unless it sees
44 * at least two temporally close I/Os to the same region. Currently, only
45 * metadata I/O is inflated. A futher enhancement could take advantage of
46 * more semantic information about the I/O. And it could use something
47 * faster than an AVL tree; that was chosen solely for convenience.
48 *
49 * There are five cache operations: allocate, fill, read, write, evict.
50 *
51 * (1) Allocate. This reserves a cache entry for the specified region.
52 * We separate the allocate and fill operations so that multiple threads
53 * don't generate I/O for the same cache miss.
54 *
55 * (2) Fill. When the I/O for a cache miss completes, the fill routine
56 * places the data in the previously allocated cache entry.
57 *
58 * (3) Read. Read data from the cache.
59 *
60 * (4) Write. Update cache contents after write completion.
61 *
62 * (5) Evict. When allocating a new entry, we evict the oldest (LRU) entry
63 * if the total cache size exceeds zfs_vdev_cache_size.
64 */
65
66/*
67 * These tunables are for performance analysis.
68 */
69/*
70 * All i/os smaller than zfs_vdev_cache_max will be turned into
71 * 1<<zfs_vdev_cache_bshift byte reads by the vdev_cache (aka software
72 * track buffer). At most zfs_vdev_cache_size bytes will be kept in each
73 * vdev's vdev_cache.
74 */
75int zfs_vdev_cache_max = 1<<14; /* 16KB */
76int zfs_vdev_cache_size = 10ULL << 20; /* 10MB */
77int zfs_vdev_cache_bshift = 16;
78
79#define VCBS (1 << zfs_vdev_cache_bshift) /* 64KB */
80
81SYSCTL_DECL(_vfs_zfs_vdev);
82SYSCTL_NODE(_vfs_zfs_vdev, OID_AUTO, cache, CTLFLAG_RW, 0, "ZFS VDEV Cache");
83TUNABLE_INT("vfs.zfs.vdev.cache.max", &zfs_vdev_cache_max);
84SYSCTL_INT(_vfs_zfs_vdev_cache, OID_AUTO, max, CTLFLAG_RDTUN,
85 &zfs_vdev_cache_max, 0, "Maximum I/O request size that increase read size");
86TUNABLE_INT("vfs.zfs.vdev.cache.size", &zfs_vdev_cache_size);
87SYSCTL_INT(_vfs_zfs_vdev_cache, OID_AUTO, size, CTLFLAG_RDTUN,
88 &zfs_vdev_cache_size, 0, "Size of VDEV cache");
89TUNABLE_INT("vfs.zfs.vdev.cache.bshift", &zfs_vdev_cache_bshift);
90SYSCTL_INT(_vfs_zfs_vdev_cache, OID_AUTO, bshift, CTLFLAG_RDTUN,
91 &zfs_vdev_cache_bshift, 0, "Turn too small requests into 1 << this value");
92
93kstat_t *vdc_ksp = NULL;
94
95typedef struct vdc_stats {
96 kstat_named_t vdc_stat_delegations;
97 kstat_named_t vdc_stat_hits;
98 kstat_named_t vdc_stat_misses;
99} vdc_stats_t;
100
101static vdc_stats_t vdc_stats = {
102 { "delegations", KSTAT_DATA_UINT64 },
103 { "hits", KSTAT_DATA_UINT64 },
104 { "misses", KSTAT_DATA_UINT64 }
105};
106
107#define VDCSTAT_BUMP(stat) atomic_add_64(&vdc_stats.stat.value.ui64, 1);
108
109static int
110vdev_cache_offset_compare(const void *a1, const void *a2)
111{
112 const vdev_cache_entry_t *ve1 = a1;
113 const vdev_cache_entry_t *ve2 = a2;
114
115 if (ve1->ve_offset < ve2->ve_offset)
116 return (-1);
117 if (ve1->ve_offset > ve2->ve_offset)
118 return (1);
119 return (0);
120}
121
122static int
123vdev_cache_lastused_compare(const void *a1, const void *a2)
124{
125 const vdev_cache_entry_t *ve1 = a1;
126 const vdev_cache_entry_t *ve2 = a2;
127
128 if (ve1->ve_lastused < ve2->ve_lastused)
129 return (-1);
130 if (ve1->ve_lastused > ve2->ve_lastused)
131 return (1);
132
133 /*
134 * Among equally old entries, sort by offset to ensure uniqueness.
135 */
136 return (vdev_cache_offset_compare(a1, a2));
137}
138
139/*
140 * Evict the specified entry from the cache.
141 */
142static void
143vdev_cache_evict(vdev_cache_t *vc, vdev_cache_entry_t *ve)
144{
145 ASSERT(MUTEX_HELD(&vc->vc_lock));
146 ASSERT(ve->ve_fill_io == NULL);
147 ASSERT(ve->ve_data != NULL);
148
149 avl_remove(&vc->vc_lastused_tree, ve);
150 avl_remove(&vc->vc_offset_tree, ve);
151 zio_buf_free(ve->ve_data, VCBS);
152 kmem_free(ve, sizeof (vdev_cache_entry_t));
153}
154
155/*
156 * Allocate an entry in the cache. At the point we don't have the data,
157 * we're just creating a placeholder so that multiple threads don't all
158 * go off and read the same blocks.
159 */
160static vdev_cache_entry_t *
161vdev_cache_allocate(zio_t *zio)
162{
163 vdev_cache_t *vc = &zio->io_vd->vdev_cache;
164 uint64_t offset = P2ALIGN(zio->io_offset, VCBS);
165 vdev_cache_entry_t *ve;
166
167 ASSERT(MUTEX_HELD(&vc->vc_lock));
168
169 if (zfs_vdev_cache_size == 0)
170 return (NULL);
171
172 /*
173 * If adding a new entry would exceed the cache size,
174 * evict the oldest entry (LRU).
175 */
176 if ((avl_numnodes(&vc->vc_lastused_tree) << zfs_vdev_cache_bshift) >
177 zfs_vdev_cache_size) {
178 ve = avl_first(&vc->vc_lastused_tree);
179 if (ve->ve_fill_io != NULL)
180 return (NULL);
181 ASSERT(ve->ve_hits != 0);
182 vdev_cache_evict(vc, ve);
183 }
184
185 ve = kmem_zalloc(sizeof (vdev_cache_entry_t), KM_SLEEP);
186 ve->ve_offset = offset;
187 ve->ve_lastused = LBOLT;
188 ve->ve_data = zio_buf_alloc(VCBS);
189
190 avl_add(&vc->vc_offset_tree, ve);
191 avl_add(&vc->vc_lastused_tree, ve);
192
193 return (ve);
194}
195
196static void
197vdev_cache_hit(vdev_cache_t *vc, vdev_cache_entry_t *ve, zio_t *zio)
198{
199 uint64_t cache_phase = P2PHASE(zio->io_offset, VCBS);
200
201 ASSERT(MUTEX_HELD(&vc->vc_lock));
202 ASSERT(ve->ve_fill_io == NULL);
203
204 if (ve->ve_lastused != LBOLT) {
205 avl_remove(&vc->vc_lastused_tree, ve);
206 ve->ve_lastused = LBOLT;
207 avl_add(&vc->vc_lastused_tree, ve);
208 }
209
210 ve->ve_hits++;
211 bcopy(ve->ve_data + cache_phase, zio->io_data, zio->io_size);
212}
213
214/*
215 * Fill a previously allocated cache entry with data.
216 */
217static void
| 23 * Use is subject to license terms.
24 */
25
26#include <sys/zfs_context.h>
27#include <sys/spa.h>
28#include <sys/vdev_impl.h>
29#include <sys/zio.h>
30#include <sys/kstat.h>
31
32/*
33 * Virtual device read-ahead caching.
34 *
35 * This file implements a simple LRU read-ahead cache. When the DMU reads
36 * a given block, it will often want other, nearby blocks soon thereafter.
37 * We take advantage of this by reading a larger disk region and caching
38 * the result. In the best case, this can turn 128 back-to-back 512-byte
39 * reads into a single 64k read followed by 127 cache hits; this reduces
40 * latency dramatically. In the worst case, it can turn an isolated 512-byte
41 * read into a 64k read, which doesn't affect latency all that much but is
42 * terribly wasteful of bandwidth. A more intelligent version of the cache
43 * could keep track of access patterns and not do read-ahead unless it sees
44 * at least two temporally close I/Os to the same region. Currently, only
45 * metadata I/O is inflated. A futher enhancement could take advantage of
46 * more semantic information about the I/O. And it could use something
47 * faster than an AVL tree; that was chosen solely for convenience.
48 *
49 * There are five cache operations: allocate, fill, read, write, evict.
50 *
51 * (1) Allocate. This reserves a cache entry for the specified region.
52 * We separate the allocate and fill operations so that multiple threads
53 * don't generate I/O for the same cache miss.
54 *
55 * (2) Fill. When the I/O for a cache miss completes, the fill routine
56 * places the data in the previously allocated cache entry.
57 *
58 * (3) Read. Read data from the cache.
59 *
60 * (4) Write. Update cache contents after write completion.
61 *
62 * (5) Evict. When allocating a new entry, we evict the oldest (LRU) entry
63 * if the total cache size exceeds zfs_vdev_cache_size.
64 */
65
66/*
67 * These tunables are for performance analysis.
68 */
69/*
70 * All i/os smaller than zfs_vdev_cache_max will be turned into
71 * 1<<zfs_vdev_cache_bshift byte reads by the vdev_cache (aka software
72 * track buffer). At most zfs_vdev_cache_size bytes will be kept in each
73 * vdev's vdev_cache.
74 */
75int zfs_vdev_cache_max = 1<<14; /* 16KB */
76int zfs_vdev_cache_size = 10ULL << 20; /* 10MB */
77int zfs_vdev_cache_bshift = 16;
78
79#define VCBS (1 << zfs_vdev_cache_bshift) /* 64KB */
80
81SYSCTL_DECL(_vfs_zfs_vdev);
82SYSCTL_NODE(_vfs_zfs_vdev, OID_AUTO, cache, CTLFLAG_RW, 0, "ZFS VDEV Cache");
83TUNABLE_INT("vfs.zfs.vdev.cache.max", &zfs_vdev_cache_max);
84SYSCTL_INT(_vfs_zfs_vdev_cache, OID_AUTO, max, CTLFLAG_RDTUN,
85 &zfs_vdev_cache_max, 0, "Maximum I/O request size that increase read size");
86TUNABLE_INT("vfs.zfs.vdev.cache.size", &zfs_vdev_cache_size);
87SYSCTL_INT(_vfs_zfs_vdev_cache, OID_AUTO, size, CTLFLAG_RDTUN,
88 &zfs_vdev_cache_size, 0, "Size of VDEV cache");
89TUNABLE_INT("vfs.zfs.vdev.cache.bshift", &zfs_vdev_cache_bshift);
90SYSCTL_INT(_vfs_zfs_vdev_cache, OID_AUTO, bshift, CTLFLAG_RDTUN,
91 &zfs_vdev_cache_bshift, 0, "Turn too small requests into 1 << this value");
92
93kstat_t *vdc_ksp = NULL;
94
95typedef struct vdc_stats {
96 kstat_named_t vdc_stat_delegations;
97 kstat_named_t vdc_stat_hits;
98 kstat_named_t vdc_stat_misses;
99} vdc_stats_t;
100
101static vdc_stats_t vdc_stats = {
102 { "delegations", KSTAT_DATA_UINT64 },
103 { "hits", KSTAT_DATA_UINT64 },
104 { "misses", KSTAT_DATA_UINT64 }
105};
106
107#define VDCSTAT_BUMP(stat) atomic_add_64(&vdc_stats.stat.value.ui64, 1);
108
109static int
110vdev_cache_offset_compare(const void *a1, const void *a2)
111{
112 const vdev_cache_entry_t *ve1 = a1;
113 const vdev_cache_entry_t *ve2 = a2;
114
115 if (ve1->ve_offset < ve2->ve_offset)
116 return (-1);
117 if (ve1->ve_offset > ve2->ve_offset)
118 return (1);
119 return (0);
120}
121
122static int
123vdev_cache_lastused_compare(const void *a1, const void *a2)
124{
125 const vdev_cache_entry_t *ve1 = a1;
126 const vdev_cache_entry_t *ve2 = a2;
127
128 if (ve1->ve_lastused < ve2->ve_lastused)
129 return (-1);
130 if (ve1->ve_lastused > ve2->ve_lastused)
131 return (1);
132
133 /*
134 * Among equally old entries, sort by offset to ensure uniqueness.
135 */
136 return (vdev_cache_offset_compare(a1, a2));
137}
138
139/*
140 * Evict the specified entry from the cache.
141 */
142static void
143vdev_cache_evict(vdev_cache_t *vc, vdev_cache_entry_t *ve)
144{
145 ASSERT(MUTEX_HELD(&vc->vc_lock));
146 ASSERT(ve->ve_fill_io == NULL);
147 ASSERT(ve->ve_data != NULL);
148
149 avl_remove(&vc->vc_lastused_tree, ve);
150 avl_remove(&vc->vc_offset_tree, ve);
151 zio_buf_free(ve->ve_data, VCBS);
152 kmem_free(ve, sizeof (vdev_cache_entry_t));
153}
154
155/*
156 * Allocate an entry in the cache. At the point we don't have the data,
157 * we're just creating a placeholder so that multiple threads don't all
158 * go off and read the same blocks.
159 */
160static vdev_cache_entry_t *
161vdev_cache_allocate(zio_t *zio)
162{
163 vdev_cache_t *vc = &zio->io_vd->vdev_cache;
164 uint64_t offset = P2ALIGN(zio->io_offset, VCBS);
165 vdev_cache_entry_t *ve;
166
167 ASSERT(MUTEX_HELD(&vc->vc_lock));
168
169 if (zfs_vdev_cache_size == 0)
170 return (NULL);
171
172 /*
173 * If adding a new entry would exceed the cache size,
174 * evict the oldest entry (LRU).
175 */
176 if ((avl_numnodes(&vc->vc_lastused_tree) << zfs_vdev_cache_bshift) >
177 zfs_vdev_cache_size) {
178 ve = avl_first(&vc->vc_lastused_tree);
179 if (ve->ve_fill_io != NULL)
180 return (NULL);
181 ASSERT(ve->ve_hits != 0);
182 vdev_cache_evict(vc, ve);
183 }
184
185 ve = kmem_zalloc(sizeof (vdev_cache_entry_t), KM_SLEEP);
186 ve->ve_offset = offset;
187 ve->ve_lastused = LBOLT;
188 ve->ve_data = zio_buf_alloc(VCBS);
189
190 avl_add(&vc->vc_offset_tree, ve);
191 avl_add(&vc->vc_lastused_tree, ve);
192
193 return (ve);
194}
195
196static void
197vdev_cache_hit(vdev_cache_t *vc, vdev_cache_entry_t *ve, zio_t *zio)
198{
199 uint64_t cache_phase = P2PHASE(zio->io_offset, VCBS);
200
201 ASSERT(MUTEX_HELD(&vc->vc_lock));
202 ASSERT(ve->ve_fill_io == NULL);
203
204 if (ve->ve_lastused != LBOLT) {
205 avl_remove(&vc->vc_lastused_tree, ve);
206 ve->ve_lastused = LBOLT;
207 avl_add(&vc->vc_lastused_tree, ve);
208 }
209
210 ve->ve_hits++;
211 bcopy(ve->ve_data + cache_phase, zio->io_data, zio->io_size);
212}
213
214/*
215 * Fill a previously allocated cache entry with data.
216 */
217static void
|
218vdev_cache_fill(zio_t *zio)
| 218vdev_cache_fill(zio_t *fio)
|
219{
| 219{
|
220 vdev_t *vd = zio->io_vd;
| 220 vdev_t *vd = fio->io_vd;
|
221 vdev_cache_t *vc = &vd->vdev_cache;
| 221 vdev_cache_t *vc = &vd->vdev_cache;
|
222 vdev_cache_entry_t *ve = zio->io_private;
223 zio_t *dio;
| 222 vdev_cache_entry_t *ve = fio->io_private;
223 zio_t *pio;
|
224
| 224
|
225 ASSERT(zio->io_size == VCBS);
| 225 ASSERT(fio->io_size == VCBS);
|
226
227 /*
228 * Add data to the cache.
229 */
230 mutex_enter(&vc->vc_lock);
231
| 226
227 /*
228 * Add data to the cache.
229 */
230 mutex_enter(&vc->vc_lock);
231
|
232 ASSERT(ve->ve_fill_io == zio);
233 ASSERT(ve->ve_offset == zio->io_offset);
234 ASSERT(ve->ve_data == zio->io_data);
| 232 ASSERT(ve->ve_fill_io == fio);
233 ASSERT(ve->ve_offset == fio->io_offset);
234 ASSERT(ve->ve_data == fio->io_data);
|
235
236 ve->ve_fill_io = NULL;
237
238 /*
239 * Even if this cache line was invalidated by a missed write update,
240 * any reads that were queued up before the missed update are still
241 * valid, so we can satisfy them from this line before we evict it.
242 */
| 235
236 ve->ve_fill_io = NULL;
237
238 /*
239 * Even if this cache line was invalidated by a missed write update,
240 * any reads that were queued up before the missed update are still
241 * valid, so we can satisfy them from this line before we evict it.
242 */
|
243 for (dio = zio->io_delegate_list; dio; dio = dio->io_delegate_next)
244 vdev_cache_hit(vc, ve, dio);
| 243 while ((pio = zio_walk_parents(fio)) != NULL)
244 vdev_cache_hit(vc, ve, pio);
|
245
| 245
|
246 if (zio->io_error || ve->ve_missed_update)
| 246 if (fio->io_error || ve->ve_missed_update)
|
247 vdev_cache_evict(vc, ve);
248
249 mutex_exit(&vc->vc_lock);
| 247 vdev_cache_evict(vc, ve);
248
249 mutex_exit(&vc->vc_lock);
|
250
251 while ((dio = zio->io_delegate_list) != NULL) {
252 zio->io_delegate_list = dio->io_delegate_next;
253 dio->io_delegate_next = NULL;
254 dio->io_error = zio->io_error;
255 zio_execute(dio);
256 }
| |
257}
258
259/*
260 * Read data from the cache. Returns 0 on cache hit, errno on a miss.
261 */
262int
263vdev_cache_read(zio_t *zio)
264{
265 vdev_cache_t *vc = &zio->io_vd->vdev_cache;
266 vdev_cache_entry_t *ve, ve_search;
267 uint64_t cache_offset = P2ALIGN(zio->io_offset, VCBS);
268 uint64_t cache_phase = P2PHASE(zio->io_offset, VCBS);
269 zio_t *fio;
270
271 ASSERT(zio->io_type == ZIO_TYPE_READ);
272
273 if (zio->io_flags & ZIO_FLAG_DONT_CACHE)
274 return (EINVAL);
275
276 if (zio->io_size > zfs_vdev_cache_max)
277 return (EOVERFLOW);
278
279 /*
280 * If the I/O straddles two or more cache blocks, don't cache it.
281 */
282 if (P2BOUNDARY(zio->io_offset, zio->io_size, VCBS))
283 return (EXDEV);
284
285 ASSERT(cache_phase + zio->io_size <= VCBS);
286
287 mutex_enter(&vc->vc_lock);
288
289 ve_search.ve_offset = cache_offset;
290 ve = avl_find(&vc->vc_offset_tree, &ve_search, NULL);
291
292 if (ve != NULL) {
293 if (ve->ve_missed_update) {
294 mutex_exit(&vc->vc_lock);
295 return (ESTALE);
296 }
297
298 if ((fio = ve->ve_fill_io) != NULL) {
| 250}
251
252/*
253 * Read data from the cache. Returns 0 on cache hit, errno on a miss.
254 */
255int
256vdev_cache_read(zio_t *zio)
257{
258 vdev_cache_t *vc = &zio->io_vd->vdev_cache;
259 vdev_cache_entry_t *ve, ve_search;
260 uint64_t cache_offset = P2ALIGN(zio->io_offset, VCBS);
261 uint64_t cache_phase = P2PHASE(zio->io_offset, VCBS);
262 zio_t *fio;
263
264 ASSERT(zio->io_type == ZIO_TYPE_READ);
265
266 if (zio->io_flags & ZIO_FLAG_DONT_CACHE)
267 return (EINVAL);
268
269 if (zio->io_size > zfs_vdev_cache_max)
270 return (EOVERFLOW);
271
272 /*
273 * If the I/O straddles two or more cache blocks, don't cache it.
274 */
275 if (P2BOUNDARY(zio->io_offset, zio->io_size, VCBS))
276 return (EXDEV);
277
278 ASSERT(cache_phase + zio->io_size <= VCBS);
279
280 mutex_enter(&vc->vc_lock);
281
282 ve_search.ve_offset = cache_offset;
283 ve = avl_find(&vc->vc_offset_tree, &ve_search, NULL);
284
285 if (ve != NULL) {
286 if (ve->ve_missed_update) {
287 mutex_exit(&vc->vc_lock);
288 return (ESTALE);
289 }
290
291 if ((fio = ve->ve_fill_io) != NULL) {
|
299 zio->io_delegate_next = fio->io_delegate_list;
300 fio->io_delegate_list = zio;
| |
301 zio_vdev_io_bypass(zio);
| 292 zio_vdev_io_bypass(zio);
|
| 293 zio_add_child(zio, fio);
|
302 mutex_exit(&vc->vc_lock);
303 VDCSTAT_BUMP(vdc_stat_delegations);
304 return (0);
305 }
306
307 vdev_cache_hit(vc, ve, zio);
308 zio_vdev_io_bypass(zio);
309
310 mutex_exit(&vc->vc_lock);
| 294 mutex_exit(&vc->vc_lock);
295 VDCSTAT_BUMP(vdc_stat_delegations);
296 return (0);
297 }
298
299 vdev_cache_hit(vc, ve, zio);
300 zio_vdev_io_bypass(zio);
301
302 mutex_exit(&vc->vc_lock);
|
311 zio_execute(zio);
| |
312 VDCSTAT_BUMP(vdc_stat_hits);
313 return (0);
314 }
315
316 ve = vdev_cache_allocate(zio);
317
318 if (ve == NULL) {
319 mutex_exit(&vc->vc_lock);
320 return (ENOMEM);
321 }
322
323 fio = zio_vdev_delegated_io(zio->io_vd, cache_offset,
324 ve->ve_data, VCBS, ZIO_TYPE_READ, ZIO_PRIORITY_CACHE_FILL,
325 ZIO_FLAG_DONT_CACHE, vdev_cache_fill, ve);
326
327 ve->ve_fill_io = fio;
| 303 VDCSTAT_BUMP(vdc_stat_hits);
304 return (0);
305 }
306
307 ve = vdev_cache_allocate(zio);
308
309 if (ve == NULL) {
310 mutex_exit(&vc->vc_lock);
311 return (ENOMEM);
312 }
313
314 fio = zio_vdev_delegated_io(zio->io_vd, cache_offset,
315 ve->ve_data, VCBS, ZIO_TYPE_READ, ZIO_PRIORITY_CACHE_FILL,
316 ZIO_FLAG_DONT_CACHE, vdev_cache_fill, ve);
317
318 ve->ve_fill_io = fio;
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328 fio->io_delegate_list = zio;
| |
329 zio_vdev_io_bypass(zio);
| 319 zio_vdev_io_bypass(zio);
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| 320 zio_add_child(zio, fio);
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330
331 mutex_exit(&vc->vc_lock);
332 zio_nowait(fio);
333 VDCSTAT_BUMP(vdc_stat_misses);
334
335 return (0);
336}
337
338/*
339 * Update cache contents upon write completion.
340 */
341void
342vdev_cache_write(zio_t *zio)
343{
344 vdev_cache_t *vc = &zio->io_vd->vdev_cache;
345 vdev_cache_entry_t *ve, ve_search;
346 uint64_t io_start = zio->io_offset;
347 uint64_t io_end = io_start + zio->io_size;
348 uint64_t min_offset = P2ALIGN(io_start, VCBS);
349 uint64_t max_offset = P2ROUNDUP(io_end, VCBS);
350 avl_index_t where;
351
352 ASSERT(zio->io_type == ZIO_TYPE_WRITE);
353
354 mutex_enter(&vc->vc_lock);
355
356 ve_search.ve_offset = min_offset;
357 ve = avl_find(&vc->vc_offset_tree, &ve_search, &where);
358
359 if (ve == NULL)
360 ve = avl_nearest(&vc->vc_offset_tree, where, AVL_AFTER);
361
362 while (ve != NULL && ve->ve_offset < max_offset) {
363 uint64_t start = MAX(ve->ve_offset, io_start);
364 uint64_t end = MIN(ve->ve_offset + VCBS, io_end);
365
366 if (ve->ve_fill_io != NULL) {
367 ve->ve_missed_update = 1;
368 } else {
369 bcopy((char *)zio->io_data + start - io_start,
370 ve->ve_data + start - ve->ve_offset, end - start);
371 }
372 ve = AVL_NEXT(&vc->vc_offset_tree, ve);
373 }
374 mutex_exit(&vc->vc_lock);
375}
376
377void
378vdev_cache_purge(vdev_t *vd)
379{
380 vdev_cache_t *vc = &vd->vdev_cache;
381 vdev_cache_entry_t *ve;
382
383 mutex_enter(&vc->vc_lock);
384 while ((ve = avl_first(&vc->vc_offset_tree)) != NULL)
385 vdev_cache_evict(vc, ve);
386 mutex_exit(&vc->vc_lock);
387}
388
389void
390vdev_cache_init(vdev_t *vd)
391{
392 vdev_cache_t *vc = &vd->vdev_cache;
393
394 mutex_init(&vc->vc_lock, NULL, MUTEX_DEFAULT, NULL);
395
396 avl_create(&vc->vc_offset_tree, vdev_cache_offset_compare,
397 sizeof (vdev_cache_entry_t),
398 offsetof(struct vdev_cache_entry, ve_offset_node));
399
400 avl_create(&vc->vc_lastused_tree, vdev_cache_lastused_compare,
401 sizeof (vdev_cache_entry_t),
402 offsetof(struct vdev_cache_entry, ve_lastused_node));
403}
404
405void
406vdev_cache_fini(vdev_t *vd)
407{
408 vdev_cache_t *vc = &vd->vdev_cache;
409
410 vdev_cache_purge(vd);
411
412 avl_destroy(&vc->vc_offset_tree);
413 avl_destroy(&vc->vc_lastused_tree);
414
415 mutex_destroy(&vc->vc_lock);
416}
417
418void
419vdev_cache_stat_init(void)
420{
421 vdc_ksp = kstat_create("zfs", 0, "vdev_cache_stats", "misc",
422 KSTAT_TYPE_NAMED, sizeof (vdc_stats) / sizeof (kstat_named_t),
423 KSTAT_FLAG_VIRTUAL);
424 if (vdc_ksp != NULL) {
425 vdc_ksp->ks_data = &vdc_stats;
426 kstat_install(vdc_ksp);
427 }
428}
429
430void
431vdev_cache_stat_fini(void)
432{
433 if (vdc_ksp != NULL) {
434 kstat_delete(vdc_ksp);
435 vdc_ksp = NULL;
436 }
437}
| 321
322 mutex_exit(&vc->vc_lock);
323 zio_nowait(fio);
324 VDCSTAT_BUMP(vdc_stat_misses);
325
326 return (0);
327}
328
329/*
330 * Update cache contents upon write completion.
331 */
332void
333vdev_cache_write(zio_t *zio)
334{
335 vdev_cache_t *vc = &zio->io_vd->vdev_cache;
336 vdev_cache_entry_t *ve, ve_search;
337 uint64_t io_start = zio->io_offset;
338 uint64_t io_end = io_start + zio->io_size;
339 uint64_t min_offset = P2ALIGN(io_start, VCBS);
340 uint64_t max_offset = P2ROUNDUP(io_end, VCBS);
341 avl_index_t where;
342
343 ASSERT(zio->io_type == ZIO_TYPE_WRITE);
344
345 mutex_enter(&vc->vc_lock);
346
347 ve_search.ve_offset = min_offset;
348 ve = avl_find(&vc->vc_offset_tree, &ve_search, &where);
349
350 if (ve == NULL)
351 ve = avl_nearest(&vc->vc_offset_tree, where, AVL_AFTER);
352
353 while (ve != NULL && ve->ve_offset < max_offset) {
354 uint64_t start = MAX(ve->ve_offset, io_start);
355 uint64_t end = MIN(ve->ve_offset + VCBS, io_end);
356
357 if (ve->ve_fill_io != NULL) {
358 ve->ve_missed_update = 1;
359 } else {
360 bcopy((char *)zio->io_data + start - io_start,
361 ve->ve_data + start - ve->ve_offset, end - start);
362 }
363 ve = AVL_NEXT(&vc->vc_offset_tree, ve);
364 }
365 mutex_exit(&vc->vc_lock);
366}
367
368void
369vdev_cache_purge(vdev_t *vd)
370{
371 vdev_cache_t *vc = &vd->vdev_cache;
372 vdev_cache_entry_t *ve;
373
374 mutex_enter(&vc->vc_lock);
375 while ((ve = avl_first(&vc->vc_offset_tree)) != NULL)
376 vdev_cache_evict(vc, ve);
377 mutex_exit(&vc->vc_lock);
378}
379
380void
381vdev_cache_init(vdev_t *vd)
382{
383 vdev_cache_t *vc = &vd->vdev_cache;
384
385 mutex_init(&vc->vc_lock, NULL, MUTEX_DEFAULT, NULL);
386
387 avl_create(&vc->vc_offset_tree, vdev_cache_offset_compare,
388 sizeof (vdev_cache_entry_t),
389 offsetof(struct vdev_cache_entry, ve_offset_node));
390
391 avl_create(&vc->vc_lastused_tree, vdev_cache_lastused_compare,
392 sizeof (vdev_cache_entry_t),
393 offsetof(struct vdev_cache_entry, ve_lastused_node));
394}
395
396void
397vdev_cache_fini(vdev_t *vd)
398{
399 vdev_cache_t *vc = &vd->vdev_cache;
400
401 vdev_cache_purge(vd);
402
403 avl_destroy(&vc->vc_offset_tree);
404 avl_destroy(&vc->vc_lastused_tree);
405
406 mutex_destroy(&vc->vc_lock);
407}
408
409void
410vdev_cache_stat_init(void)
411{
412 vdc_ksp = kstat_create("zfs", 0, "vdev_cache_stats", "misc",
413 KSTAT_TYPE_NAMED, sizeof (vdc_stats) / sizeof (kstat_named_t),
414 KSTAT_FLAG_VIRTUAL);
415 if (vdc_ksp != NULL) {
416 vdc_ksp->ks_data = &vdc_stats;
417 kstat_install(vdc_ksp);
418 }
419}
420
421void
422vdev_cache_stat_fini(void)
423{
424 if (vdc_ksp != NULL) {
425 kstat_delete(vdc_ksp);
426 vdc_ksp = NULL;
427 }
428}
|