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.
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.
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]
22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
27 * DVA-based Adjustable Replacement Cache
29 * While much of the theory of operation used here is
30 * based on the self-tuning, low overhead replacement cache
31 * presented by Megiddo and Modha at FAST 2003, there are some
32 * significant differences:
34 * 1. The Megiddo and Modha model assumes any page is evictable.
35 * Pages in its cache cannot be "locked" into memory. This makes
36 * the eviction algorithm simple: evict the last page in the list.
37 * This also make the performance characteristics easy to reason
38 * about. Our cache is not so simple. At any given moment, some
39 * subset of the blocks in the cache are un-evictable because we
40 * have handed out a reference to them. Blocks are only evictable
41 * when there are no external references active. This makes
42 * eviction far more problematic: we choose to evict the evictable
43 * blocks that are the "lowest" in the list.
45 * There are times when it is not possible to evict the requested
46 * space. In these circumstances we are unable to adjust the cache
47 * size. To prevent the cache growing unbounded at these times we
48 * implement a "cache throttle" that slows the flow of new data
49 * into the cache until we can make space available.
51 * 2. The Megiddo and Modha model assumes a fixed cache size.
52 * Pages are evicted when the cache is full and there is a cache
53 * miss. Our model has a variable sized cache. It grows with
54 * high use, but also tries to react to memory pressure from the
55 * operating system: decreasing its size when system memory is
58 * 3. The Megiddo and Modha model assumes a fixed page size. All
59 * elements of the cache are therefor exactly the same size. So
60 * when adjusting the cache size following a cache miss, its simply
61 * a matter of choosing a single page to evict. In our model, we
62 * have variable sized cache blocks (rangeing from 512 bytes to
63 * 128K bytes). We therefor choose a set of blocks to evict to make
64 * space for a cache miss that approximates as closely as possible
65 * the space used by the new block.
67 * See also: "ARC: A Self-Tuning, Low Overhead Replacement Cache"
68 * by N. Megiddo & D. Modha, FAST 2003
74 * A new reference to a cache buffer can be obtained in two
75 * ways: 1) via a hash table lookup using the DVA as a key,
76 * or 2) via one of the ARC lists. The arc_read() interface
77 * uses method 1, while the internal arc algorithms for
78 * adjusting the cache use method 2. We therefor provide two
79 * types of locks: 1) the hash table lock array, and 2) the
82 * Buffers do not have their own mutexs, rather they rely on the
83 * hash table mutexs for the bulk of their protection (i.e. most
84 * fields in the arc_buf_hdr_t are protected by these mutexs).
86 * buf_hash_find() returns the appropriate mutex (held) when it
87 * locates the requested buffer in the hash table. It returns
88 * NULL for the mutex if the buffer was not in the table.
90 * buf_hash_remove() expects the appropriate hash mutex to be
91 * already held before it is invoked.
93 * Each arc state also has a mutex which is used to protect the
94 * buffer list associated with the state. When attempting to
95 * obtain a hash table lock while holding an arc list lock you
96 * must use: mutex_tryenter() to avoid deadlock. Also note that
97 * the active state mutex must be held before the ghost state mutex.
99 * Arc buffers may have an associated eviction callback function.
100 * This function will be invoked prior to removing the buffer (e.g.
101 * in arc_do_user_evicts()). Note however that the data associated
102 * with the buffer may be evicted prior to the callback. The callback
103 * must be made with *no locks held* (to prevent deadlock). Additionally,
104 * the users of callbacks must ensure that their private data is
105 * protected from simultaneous callbacks from arc_buf_evict()
106 * and arc_do_user_evicts().
108 * Note that the majority of the performance stats are manipulated
109 * with atomic operations.
111 * The L2ARC uses the l2arc_buflist_mtx global mutex for the following:
113 * - L2ARC buflist creation
114 * - L2ARC buflist eviction
115 * - L2ARC write completion, which walks L2ARC buflists
116 * - ARC header destruction, as it removes from L2ARC buflists
117 * - ARC header release, as it removes from L2ARC buflists
122 #include <sys/zio_checksum.h>
123 #include <sys/zfs_context.h>
125 #include <sys/refcount.h>
126 #include <sys/vdev.h>
128 #include <sys/vmsystm.h>
130 #include <sys/fs/swapnode.h>
131 #include <sys/dnlc.h>
133 #include <sys/callb.h>
134 #include <sys/kstat.h>
136 static kmutex_t arc_reclaim_thr_lock
;
137 static kcondvar_t arc_reclaim_thr_cv
; /* used to signal reclaim thr */
138 static uint8_t arc_thread_exit
;
140 extern int zfs_write_limit_shift
;
141 extern uint64_t zfs_write_limit_max
;
142 extern kmutex_t zfs_write_limit_lock
;
144 #define ARC_REDUCE_DNLC_PERCENT 3
145 uint_t arc_reduce_dnlc_percent
= ARC_REDUCE_DNLC_PERCENT
;
147 typedef enum arc_reclaim_strategy
{
148 ARC_RECLAIM_AGGR
, /* Aggressive reclaim strategy */
149 ARC_RECLAIM_CONS
/* Conservative reclaim strategy */
150 } arc_reclaim_strategy_t
;
152 /* number of seconds before growing cache again */
153 static int arc_grow_retry
= 60;
155 /* shift of arc_c for calculating both min and max arc_p */
156 static int arc_p_min_shift
= 4;
158 /* log2(fraction of arc to reclaim) */
159 static int arc_shrink_shift
= 5;
162 * minimum lifespan of a prefetch block in clock ticks
163 * (initialized in arc_init())
165 static int arc_min_prefetch_lifespan
;
170 * The arc has filled available memory and has now warmed up.
172 static boolean_t arc_warm
;
175 * These tunables are for performance analysis.
177 uint64_t zfs_arc_max
;
178 uint64_t zfs_arc_min
;
179 uint64_t zfs_arc_meta_limit
= 0;
180 int zfs_mdcomp_disable
= 0;
181 int zfs_arc_grow_retry
= 0;
182 int zfs_arc_shrink_shift
= 0;
183 int zfs_arc_p_min_shift
= 0;
186 * Note that buffers can be in one of 6 states:
187 * ARC_anon - anonymous (discussed below)
188 * ARC_mru - recently used, currently cached
189 * ARC_mru_ghost - recentely used, no longer in cache
190 * ARC_mfu - frequently used, currently cached
191 * ARC_mfu_ghost - frequently used, no longer in cache
192 * ARC_l2c_only - exists in L2ARC but not other states
193 * When there are no active references to the buffer, they are
194 * are linked onto a list in one of these arc states. These are
195 * the only buffers that can be evicted or deleted. Within each
196 * state there are multiple lists, one for meta-data and one for
197 * non-meta-data. Meta-data (indirect blocks, blocks of dnodes,
198 * etc.) is tracked separately so that it can be managed more
199 * explicitly: favored over data, limited explicitly.
201 * Anonymous buffers are buffers that are not associated with
202 * a DVA. These are buffers that hold dirty block copies
203 * before they are written to stable storage. By definition,
204 * they are "ref'd" and are considered part of arc_mru
205 * that cannot be freed. Generally, they will aquire a DVA
206 * as they are written and migrate onto the arc_mru list.
208 * The ARC_l2c_only state is for buffers that are in the second
209 * level ARC but no longer in any of the ARC_m* lists. The second
210 * level ARC itself may also contain buffers that are in any of
211 * the ARC_m* states - meaning that a buffer can exist in two
212 * places. The reason for the ARC_l2c_only state is to keep the
213 * buffer header in the hash table, so that reads that hit the
214 * second level ARC benefit from these fast lookups.
217 typedef struct arc_state
{
218 list_t arcs_list
[ARC_BUFC_NUMTYPES
]; /* list of evictable buffers */
219 uint64_t arcs_lsize
[ARC_BUFC_NUMTYPES
]; /* amount of evictable data */
220 uint64_t arcs_size
; /* total amount of data in this state */
225 static arc_state_t ARC_anon
;
226 static arc_state_t ARC_mru
;
227 static arc_state_t ARC_mru_ghost
;
228 static arc_state_t ARC_mfu
;
229 static arc_state_t ARC_mfu_ghost
;
230 static arc_state_t ARC_l2c_only
;
232 typedef struct arc_stats
{
233 kstat_named_t arcstat_hits
;
234 kstat_named_t arcstat_misses
;
235 kstat_named_t arcstat_demand_data_hits
;
236 kstat_named_t arcstat_demand_data_misses
;
237 kstat_named_t arcstat_demand_metadata_hits
;
238 kstat_named_t arcstat_demand_metadata_misses
;
239 kstat_named_t arcstat_prefetch_data_hits
;
240 kstat_named_t arcstat_prefetch_data_misses
;
241 kstat_named_t arcstat_prefetch_metadata_hits
;
242 kstat_named_t arcstat_prefetch_metadata_misses
;
243 kstat_named_t arcstat_mru_hits
;
244 kstat_named_t arcstat_mru_ghost_hits
;
245 kstat_named_t arcstat_mfu_hits
;
246 kstat_named_t arcstat_mfu_ghost_hits
;
247 kstat_named_t arcstat_deleted
;
248 kstat_named_t arcstat_recycle_miss
;
249 kstat_named_t arcstat_mutex_miss
;
250 kstat_named_t arcstat_evict_skip
;
251 kstat_named_t arcstat_hash_elements
;
252 kstat_named_t arcstat_hash_elements_max
;
253 kstat_named_t arcstat_hash_collisions
;
254 kstat_named_t arcstat_hash_chains
;
255 kstat_named_t arcstat_hash_chain_max
;
256 kstat_named_t arcstat_p
;
257 kstat_named_t arcstat_c
;
258 kstat_named_t arcstat_c_min
;
259 kstat_named_t arcstat_c_max
;
260 kstat_named_t arcstat_size
;
261 kstat_named_t arcstat_hdr_size
;
262 kstat_named_t arcstat_data_size
;
263 kstat_named_t arcstat_other_size
;
264 kstat_named_t arcstat_l2_hits
;
265 kstat_named_t arcstat_l2_misses
;
266 kstat_named_t arcstat_l2_feeds
;
267 kstat_named_t arcstat_l2_rw_clash
;
268 kstat_named_t arcstat_l2_read_bytes
;
269 kstat_named_t arcstat_l2_write_bytes
;
270 kstat_named_t arcstat_l2_writes_sent
;
271 kstat_named_t arcstat_l2_writes_done
;
272 kstat_named_t arcstat_l2_writes_error
;
273 kstat_named_t arcstat_l2_writes_hdr_miss
;
274 kstat_named_t arcstat_l2_evict_lock_retry
;
275 kstat_named_t arcstat_l2_evict_reading
;
276 kstat_named_t arcstat_l2_free_on_write
;
277 kstat_named_t arcstat_l2_abort_lowmem
;
278 kstat_named_t arcstat_l2_cksum_bad
;
279 kstat_named_t arcstat_l2_io_error
;
280 kstat_named_t arcstat_l2_size
;
281 kstat_named_t arcstat_l2_hdr_size
;
282 kstat_named_t arcstat_memory_throttle_count
;
285 static arc_stats_t arc_stats
= {
286 { "hits", KSTAT_DATA_UINT64
},
287 { "misses", KSTAT_DATA_UINT64
},
288 { "demand_data_hits", KSTAT_DATA_UINT64
},
289 { "demand_data_misses", KSTAT_DATA_UINT64
},
290 { "demand_metadata_hits", KSTAT_DATA_UINT64
},
291 { "demand_metadata_misses", KSTAT_DATA_UINT64
},
292 { "prefetch_data_hits", KSTAT_DATA_UINT64
},
293 { "prefetch_data_misses", KSTAT_DATA_UINT64
},
294 { "prefetch_metadata_hits", KSTAT_DATA_UINT64
},
295 { "prefetch_metadata_misses", KSTAT_DATA_UINT64
},
296 { "mru_hits", KSTAT_DATA_UINT64
},
297 { "mru_ghost_hits", KSTAT_DATA_UINT64
},
298 { "mfu_hits", KSTAT_DATA_UINT64
},
299 { "mfu_ghost_hits", KSTAT_DATA_UINT64
},
300 { "deleted", KSTAT_DATA_UINT64
},
301 { "recycle_miss", KSTAT_DATA_UINT64
},
302 { "mutex_miss", KSTAT_DATA_UINT64
},
303 { "evict_skip", KSTAT_DATA_UINT64
},
304 { "hash_elements", KSTAT_DATA_UINT64
},
305 { "hash_elements_max", KSTAT_DATA_UINT64
},
306 { "hash_collisions", KSTAT_DATA_UINT64
},
307 { "hash_chains", KSTAT_DATA_UINT64
},
308 { "hash_chain_max", KSTAT_DATA_UINT64
},
309 { "p", KSTAT_DATA_UINT64
},
310 { "c", KSTAT_DATA_UINT64
},
311 { "c_min", KSTAT_DATA_UINT64
},
312 { "c_max", KSTAT_DATA_UINT64
},
313 { "size", KSTAT_DATA_UINT64
},
314 { "hdr_size", KSTAT_DATA_UINT64
},
315 { "data_size", KSTAT_DATA_UINT64
},
316 { "other_size", KSTAT_DATA_UINT64
},
317 { "l2_hits", KSTAT_DATA_UINT64
},
318 { "l2_misses", KSTAT_DATA_UINT64
},
319 { "l2_feeds", KSTAT_DATA_UINT64
},
320 { "l2_rw_clash", KSTAT_DATA_UINT64
},
321 { "l2_read_bytes", KSTAT_DATA_UINT64
},
322 { "l2_write_bytes", KSTAT_DATA_UINT64
},
323 { "l2_writes_sent", KSTAT_DATA_UINT64
},
324 { "l2_writes_done", KSTAT_DATA_UINT64
},
325 { "l2_writes_error", KSTAT_DATA_UINT64
},
326 { "l2_writes_hdr_miss", KSTAT_DATA_UINT64
},
327 { "l2_evict_lock_retry", KSTAT_DATA_UINT64
},
328 { "l2_evict_reading", KSTAT_DATA_UINT64
},
329 { "l2_free_on_write", KSTAT_DATA_UINT64
},
330 { "l2_abort_lowmem", KSTAT_DATA_UINT64
},
331 { "l2_cksum_bad", KSTAT_DATA_UINT64
},
332 { "l2_io_error", KSTAT_DATA_UINT64
},
333 { "l2_size", KSTAT_DATA_UINT64
},
334 { "l2_hdr_size", KSTAT_DATA_UINT64
},
335 { "memory_throttle_count", KSTAT_DATA_UINT64
}
338 #define ARCSTAT(stat) (arc_stats.stat.value.ui64)
340 #define ARCSTAT_INCR(stat, val) \
341 atomic_add_64(&arc_stats.stat.value.ui64, (val));
343 #define ARCSTAT_BUMP(stat) ARCSTAT_INCR(stat, 1)
344 #define ARCSTAT_BUMPDOWN(stat) ARCSTAT_INCR(stat, -1)
346 #define ARCSTAT_MAX(stat, val) { \
348 while ((val) > (m = arc_stats.stat.value.ui64) && \
349 (m != atomic_cas_64(&arc_stats.stat.value.ui64, m, (val)))) \
353 #define ARCSTAT_MAXSTAT(stat) \
354 ARCSTAT_MAX(stat##_max, arc_stats.stat.value.ui64)
357 * We define a macro to allow ARC hits/misses to be easily broken down by
358 * two separate conditions, giving a total of four different subtypes for
359 * each of hits and misses (so eight statistics total).
361 #define ARCSTAT_CONDSTAT(cond1, stat1, notstat1, cond2, stat2, notstat2, stat) \
364 ARCSTAT_BUMP(arcstat_##stat1##_##stat2##_##stat); \
366 ARCSTAT_BUMP(arcstat_##stat1##_##notstat2##_##stat); \
370 ARCSTAT_BUMP(arcstat_##notstat1##_##stat2##_##stat); \
372 ARCSTAT_BUMP(arcstat_##notstat1##_##notstat2##_##stat);\
377 static arc_state_t
*arc_anon
;
378 static arc_state_t
*arc_mru
;
379 static arc_state_t
*arc_mru_ghost
;
380 static arc_state_t
*arc_mfu
;
381 static arc_state_t
*arc_mfu_ghost
;
382 static arc_state_t
*arc_l2c_only
;
385 * There are several ARC variables that are critical to export as kstats --
386 * but we don't want to have to grovel around in the kstat whenever we wish to
387 * manipulate them. For these variables, we therefore define them to be in
388 * terms of the statistic variable. This assures that we are not introducing
389 * the possibility of inconsistency by having shadow copies of the variables,
390 * while still allowing the code to be readable.
392 #define arc_size ARCSTAT(arcstat_size) /* actual total arc size */
393 #define arc_p ARCSTAT(arcstat_p) /* target size of MRU */
394 #define arc_c ARCSTAT(arcstat_c) /* target size of cache */
395 #define arc_c_min ARCSTAT(arcstat_c_min) /* min target cache size */
396 #define arc_c_max ARCSTAT(arcstat_c_max) /* max target cache size */
398 static int arc_no_grow
; /* Don't try to grow cache size */
399 static uint64_t arc_tempreserve
;
400 static uint64_t arc_meta_used
;
401 static uint64_t arc_meta_limit
;
402 static uint64_t arc_meta_max
= 0;
404 typedef struct l2arc_buf_hdr l2arc_buf_hdr_t
;
406 typedef struct arc_callback arc_callback_t
;
408 struct arc_callback
{
410 arc_done_func_t
*acb_done
;
412 zio_t
*acb_zio_dummy
;
413 arc_callback_t
*acb_next
;
416 typedef struct arc_write_callback arc_write_callback_t
;
418 struct arc_write_callback
{
420 arc_done_func_t
*awcb_ready
;
421 arc_done_func_t
*awcb_done
;
426 /* protected by hash lock */
431 kmutex_t b_freeze_lock
;
432 zio_cksum_t
*b_freeze_cksum
;
434 arc_buf_hdr_t
*b_hash_next
;
439 arc_callback_t
*b_acb
;
443 arc_buf_contents_t b_type
;
447 /* protected by arc state mutex */
448 arc_state_t
*b_state
;
449 list_node_t b_arc_node
;
451 /* updated atomically */
452 clock_t b_arc_access
;
454 /* self protecting */
457 l2arc_buf_hdr_t
*b_l2hdr
;
458 list_node_t b_l2node
;
461 static arc_buf_t
*arc_eviction_list
;
462 static kmutex_t arc_eviction_mtx
;
463 static arc_buf_hdr_t arc_eviction_hdr
;
464 static void arc_get_data_buf(arc_buf_t
*buf
);
465 static void arc_access(arc_buf_hdr_t
*buf
, kmutex_t
*hash_lock
);
466 static int arc_evict_needed(arc_buf_contents_t type
);
467 static void arc_evict_ghost(arc_state_t
*state
, uint64_t spa
, int64_t bytes
);
469 #define GHOST_STATE(state) \
470 ((state) == arc_mru_ghost || (state) == arc_mfu_ghost || \
471 (state) == arc_l2c_only)
474 * Private ARC flags. These flags are private ARC only flags that will show up
475 * in b_flags in the arc_hdr_buf_t. Some flags are publicly declared, and can
476 * be passed in as arc_flags in things like arc_read. However, these flags
477 * should never be passed and should only be set by ARC code. When adding new
478 * public flags, make sure not to smash the private ones.
481 #define ARC_IN_HASH_TABLE (1 << 9) /* this buffer is hashed */
482 #define ARC_IO_IN_PROGRESS (1 << 10) /* I/O in progress for buf */
483 #define ARC_IO_ERROR (1 << 11) /* I/O failed for buf */
484 #define ARC_FREED_IN_READ (1 << 12) /* buf freed while in read */
485 #define ARC_BUF_AVAILABLE (1 << 13) /* block not in active use */
486 #define ARC_INDIRECT (1 << 14) /* this is an indirect block */
487 #define ARC_FREE_IN_PROGRESS (1 << 15) /* hdr about to be freed */
488 #define ARC_L2_WRITING (1 << 16) /* L2ARC write in progress */
489 #define ARC_L2_EVICTED (1 << 17) /* evicted during I/O */
490 #define ARC_L2_WRITE_HEAD (1 << 18) /* head of write list */
491 #define ARC_STORED (1 << 19) /* has been store()d to */
493 #define HDR_IN_HASH_TABLE(hdr) ((hdr)->b_flags & ARC_IN_HASH_TABLE)
494 #define HDR_IO_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_IO_IN_PROGRESS)
495 #define HDR_IO_ERROR(hdr) ((hdr)->b_flags & ARC_IO_ERROR)
496 #define HDR_PREFETCH(hdr) ((hdr)->b_flags & ARC_PREFETCH)
497 #define HDR_FREED_IN_READ(hdr) ((hdr)->b_flags & ARC_FREED_IN_READ)
498 #define HDR_BUF_AVAILABLE(hdr) ((hdr)->b_flags & ARC_BUF_AVAILABLE)
499 #define HDR_FREE_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_FREE_IN_PROGRESS)
500 #define HDR_L2CACHE(hdr) ((hdr)->b_flags & ARC_L2CACHE)
501 #define HDR_L2_READING(hdr) ((hdr)->b_flags & ARC_IO_IN_PROGRESS && \
502 (hdr)->b_l2hdr != NULL)
503 #define HDR_L2_WRITING(hdr) ((hdr)->b_flags & ARC_L2_WRITING)
504 #define HDR_L2_EVICTED(hdr) ((hdr)->b_flags & ARC_L2_EVICTED)
505 #define HDR_L2_WRITE_HEAD(hdr) ((hdr)->b_flags & ARC_L2_WRITE_HEAD)
511 #define HDR_SIZE ((int64_t)sizeof (arc_buf_hdr_t))
512 #define L2HDR_SIZE ((int64_t)sizeof (l2arc_buf_hdr_t))
515 * Hash table routines
518 #define HT_LOCK_PAD 64
523 unsigned char pad
[(HT_LOCK_PAD
- sizeof (kmutex_t
))];
527 #define BUF_LOCKS 256
528 typedef struct buf_hash_table
{
530 arc_buf_hdr_t
**ht_table
;
531 struct ht_lock ht_locks
[BUF_LOCKS
];
534 static buf_hash_table_t buf_hash_table
;
536 #define BUF_HASH_INDEX(spa, dva, birth) \
537 (buf_hash(spa, dva, birth) & buf_hash_table.ht_mask)
538 #define BUF_HASH_LOCK_NTRY(idx) (buf_hash_table.ht_locks[idx & (BUF_LOCKS-1)])
539 #define BUF_HASH_LOCK(idx) (&(BUF_HASH_LOCK_NTRY(idx).ht_lock))
540 #define HDR_LOCK(buf) \
541 (BUF_HASH_LOCK(BUF_HASH_INDEX(buf->b_spa, &buf->b_dva, buf->b_birth)))
543 uint64_t zfs_crc64_table
[256];
549 #define L2ARC_WRITE_SIZE (8 * 1024 * 1024) /* initial write max */
550 #define L2ARC_HEADROOM 2 /* num of writes */
551 #define L2ARC_FEED_SECS 1 /* caching interval secs */
552 #define L2ARC_FEED_MIN_MS 200 /* min caching interval ms */
554 #define l2arc_writes_sent ARCSTAT(arcstat_l2_writes_sent)
555 #define l2arc_writes_done ARCSTAT(arcstat_l2_writes_done)
558 * L2ARC Performance Tunables
560 uint64_t l2arc_write_max
= L2ARC_WRITE_SIZE
; /* default max write size */
561 uint64_t l2arc_write_boost
= L2ARC_WRITE_SIZE
; /* extra write during warmup */
562 uint64_t l2arc_headroom
= L2ARC_HEADROOM
; /* number of dev writes */
563 uint64_t l2arc_feed_secs
= L2ARC_FEED_SECS
; /* interval seconds */
564 uint64_t l2arc_feed_min_ms
= L2ARC_FEED_MIN_MS
; /* min interval milliseconds */
565 boolean_t l2arc_noprefetch
= B_TRUE
; /* don't cache prefetch bufs */
566 boolean_t l2arc_feed_again
= B_TRUE
; /* turbo warmup */
567 boolean_t l2arc_norw
= B_TRUE
; /* no reads during writes */
572 typedef struct l2arc_dev
{
573 vdev_t
*l2ad_vdev
; /* vdev */
574 spa_t
*l2ad_spa
; /* spa */
575 uint64_t l2ad_hand
; /* next write location */
576 uint64_t l2ad_write
; /* desired write size, bytes */
577 uint64_t l2ad_boost
; /* warmup write boost, bytes */
578 uint64_t l2ad_start
; /* first addr on device */
579 uint64_t l2ad_end
; /* last addr on device */
580 uint64_t l2ad_evict
; /* last addr eviction reached */
581 boolean_t l2ad_first
; /* first sweep through */
582 boolean_t l2ad_writing
; /* currently writing */
583 list_t
*l2ad_buflist
; /* buffer list */
584 list_node_t l2ad_node
; /* device list node */
587 static list_t L2ARC_dev_list
; /* device list */
588 static list_t
*l2arc_dev_list
; /* device list pointer */
589 static kmutex_t l2arc_dev_mtx
; /* device list mutex */
590 static l2arc_dev_t
*l2arc_dev_last
; /* last device used */
591 static kmutex_t l2arc_buflist_mtx
; /* mutex for all buflists */
592 static list_t L2ARC_free_on_write
; /* free after write buf list */
593 static list_t
*l2arc_free_on_write
; /* free after write list ptr */
594 static kmutex_t l2arc_free_on_write_mtx
; /* mutex for list */
595 static uint64_t l2arc_ndev
; /* number of devices */
597 typedef struct l2arc_read_callback
{
598 arc_buf_t
*l2rcb_buf
; /* read buffer */
599 spa_t
*l2rcb_spa
; /* spa */
600 blkptr_t l2rcb_bp
; /* original blkptr */
601 zbookmark_t l2rcb_zb
; /* original bookmark */
602 int l2rcb_flags
; /* original flags */
603 } l2arc_read_callback_t
;
605 typedef struct l2arc_write_callback
{
606 l2arc_dev_t
*l2wcb_dev
; /* device info */
607 arc_buf_hdr_t
*l2wcb_head
; /* head of write buflist */
608 } l2arc_write_callback_t
;
610 struct l2arc_buf_hdr
{
611 /* protected by arc_buf_hdr mutex */
612 l2arc_dev_t
*b_dev
; /* L2ARC device */
613 daddr_t b_daddr
; /* disk address, offset byte */
616 typedef struct l2arc_data_free
{
617 /* protected by l2arc_free_on_write_mtx */
620 void (*l2df_func
)(void *, size_t);
621 list_node_t l2df_list_node
;
624 static kmutex_t l2arc_feed_thr_lock
;
625 static kcondvar_t l2arc_feed_thr_cv
;
626 static uint8_t l2arc_thread_exit
;
628 static void l2arc_read_done(zio_t
*zio
);
629 static void l2arc_hdr_stat_add(void);
630 static void l2arc_hdr_stat_remove(void);
633 buf_hash(uint64_t spa
, const dva_t
*dva
, uint64_t birth
)
635 uint8_t *vdva
= (uint8_t *)dva
;
636 uint64_t crc
= -1ULL;
639 ASSERT(zfs_crc64_table
[128] == ZFS_CRC64_POLY
);
641 for (i
= 0; i
< sizeof (dva_t
); i
++)
642 crc
= (crc
>> 8) ^ zfs_crc64_table
[(crc
^ vdva
[i
]) & 0xFF];
644 crc
^= (spa
>>8) ^ birth
;
649 #define BUF_EMPTY(buf) \
650 ((buf)->b_dva.dva_word[0] == 0 && \
651 (buf)->b_dva.dva_word[1] == 0 && \
654 #define BUF_EQUAL(spa, dva, birth, buf) \
655 ((buf)->b_dva.dva_word[0] == (dva)->dva_word[0]) && \
656 ((buf)->b_dva.dva_word[1] == (dva)->dva_word[1]) && \
657 ((buf)->b_birth == birth) && ((buf)->b_spa == spa)
659 static arc_buf_hdr_t
*
660 buf_hash_find(uint64_t spa
, const dva_t
*dva
, uint64_t birth
, kmutex_t
**lockp
)
662 uint64_t idx
= BUF_HASH_INDEX(spa
, dva
, birth
);
663 kmutex_t
*hash_lock
= BUF_HASH_LOCK(idx
);
666 mutex_enter(hash_lock
);
667 for (buf
= buf_hash_table
.ht_table
[idx
]; buf
!= NULL
;
668 buf
= buf
->b_hash_next
) {
669 if (BUF_EQUAL(spa
, dva
, birth
, buf
)) {
674 mutex_exit(hash_lock
);
680 * Insert an entry into the hash table. If there is already an element
681 * equal to elem in the hash table, then the already existing element
682 * will be returned and the new element will not be inserted.
683 * Otherwise returns NULL.
685 static arc_buf_hdr_t
*
686 buf_hash_insert(arc_buf_hdr_t
*buf
, kmutex_t
**lockp
)
688 uint64_t idx
= BUF_HASH_INDEX(buf
->b_spa
, &buf
->b_dva
, buf
->b_birth
);
689 kmutex_t
*hash_lock
= BUF_HASH_LOCK(idx
);
693 ASSERT(!HDR_IN_HASH_TABLE(buf
));
695 mutex_enter(hash_lock
);
696 for (fbuf
= buf_hash_table
.ht_table
[idx
], i
= 0; fbuf
!= NULL
;
697 fbuf
= fbuf
->b_hash_next
, i
++) {
698 if (BUF_EQUAL(buf
->b_spa
, &buf
->b_dva
, buf
->b_birth
, fbuf
))
702 buf
->b_hash_next
= buf_hash_table
.ht_table
[idx
];
703 buf_hash_table
.ht_table
[idx
] = buf
;
704 buf
->b_flags
|= ARC_IN_HASH_TABLE
;
706 /* collect some hash table performance data */
708 ARCSTAT_BUMP(arcstat_hash_collisions
);
710 ARCSTAT_BUMP(arcstat_hash_chains
);
712 ARCSTAT_MAX(arcstat_hash_chain_max
, i
);
715 ARCSTAT_BUMP(arcstat_hash_elements
);
716 ARCSTAT_MAXSTAT(arcstat_hash_elements
);
722 buf_hash_remove(arc_buf_hdr_t
*buf
)
724 arc_buf_hdr_t
*fbuf
, **bufp
;
725 uint64_t idx
= BUF_HASH_INDEX(buf
->b_spa
, &buf
->b_dva
, buf
->b_birth
);
727 ASSERT(MUTEX_HELD(BUF_HASH_LOCK(idx
)));
728 ASSERT(HDR_IN_HASH_TABLE(buf
));
730 bufp
= &buf_hash_table
.ht_table
[idx
];
731 while ((fbuf
= *bufp
) != buf
) {
732 ASSERT(fbuf
!= NULL
);
733 bufp
= &fbuf
->b_hash_next
;
735 *bufp
= buf
->b_hash_next
;
736 buf
->b_hash_next
= NULL
;
737 buf
->b_flags
&= ~ARC_IN_HASH_TABLE
;
739 /* collect some hash table performance data */
740 ARCSTAT_BUMPDOWN(arcstat_hash_elements
);
742 if (buf_hash_table
.ht_table
[idx
] &&
743 buf_hash_table
.ht_table
[idx
]->b_hash_next
== NULL
)
744 ARCSTAT_BUMPDOWN(arcstat_hash_chains
);
748 * Global data structures and functions for the buf kmem cache.
750 static kmem_cache_t
*hdr_cache
;
751 static kmem_cache_t
*buf_cache
;
758 kmem_free(buf_hash_table
.ht_table
,
759 (buf_hash_table
.ht_mask
+ 1) * sizeof (void *));
760 for (i
= 0; i
< BUF_LOCKS
; i
++)
761 mutex_destroy(&buf_hash_table
.ht_locks
[i
].ht_lock
);
762 kmem_cache_destroy(hdr_cache
);
763 kmem_cache_destroy(buf_cache
);
767 * Constructor callback - called when the cache is empty
768 * and a new buf is requested.
772 hdr_cons(void *vbuf
, void *unused
, int kmflag
)
774 arc_buf_hdr_t
*buf
= vbuf
;
776 bzero(buf
, sizeof (arc_buf_hdr_t
));
777 refcount_create(&buf
->b_refcnt
);
778 cv_init(&buf
->b_cv
, NULL
, CV_DEFAULT
, NULL
);
779 mutex_init(&buf
->b_freeze_lock
, NULL
, MUTEX_DEFAULT
, NULL
);
780 arc_space_consume(sizeof (arc_buf_hdr_t
), ARC_SPACE_HDRS
);
787 buf_cons(void *vbuf
, void *unused
, int kmflag
)
789 arc_buf_t
*buf
= vbuf
;
791 bzero(buf
, sizeof (arc_buf_t
));
792 rw_init(&buf
->b_lock
, NULL
, RW_DEFAULT
, NULL
);
793 arc_space_consume(sizeof (arc_buf_t
), ARC_SPACE_HDRS
);
799 * Destructor callback - called when a cached buf is
800 * no longer required.
804 hdr_dest(void *vbuf
, void *unused
)
806 arc_buf_hdr_t
*buf
= vbuf
;
808 refcount_destroy(&buf
->b_refcnt
);
809 cv_destroy(&buf
->b_cv
);
810 mutex_destroy(&buf
->b_freeze_lock
);
811 arc_space_return(sizeof (arc_buf_hdr_t
), ARC_SPACE_HDRS
);
816 buf_dest(void *vbuf
, void *unused
)
818 arc_buf_t
*buf
= vbuf
;
820 rw_destroy(&buf
->b_lock
);
821 arc_space_return(sizeof (arc_buf_t
), ARC_SPACE_HDRS
);
825 * Reclaim callback -- invoked when memory is low.
829 hdr_recl(void *unused
)
831 dprintf("hdr_recl called\n");
833 * umem calls the reclaim func when we destroy the buf cache,
834 * which is after we do arc_fini().
837 cv_signal(&arc_reclaim_thr_cv
);
844 uint64_t hsize
= 1ULL << 12;
848 * The hash table is big enough to fill all of physical memory
849 * with an average 64K block size. The table will take up
850 * totalmem*sizeof(void*)/64K (eg. 128KB/GB with 8-byte pointers).
852 while (hsize
* 65536 < physmem
* PAGESIZE
)
855 buf_hash_table
.ht_mask
= hsize
- 1;
856 buf_hash_table
.ht_table
=
857 kmem_zalloc(hsize
* sizeof (void*), KM_NOSLEEP
);
858 if (buf_hash_table
.ht_table
== NULL
) {
859 ASSERT(hsize
> (1ULL << 8));
864 hdr_cache
= kmem_cache_create("arc_buf_hdr_t", sizeof (arc_buf_hdr_t
),
865 0, hdr_cons
, hdr_dest
, hdr_recl
, NULL
, NULL
, 0);
866 buf_cache
= kmem_cache_create("arc_buf_t", sizeof (arc_buf_t
),
867 0, buf_cons
, buf_dest
, NULL
, NULL
, NULL
, 0);
869 for (i
= 0; i
< 256; i
++)
870 for (ct
= zfs_crc64_table
+ i
, *ct
= i
, j
= 8; j
> 0; j
--)
871 *ct
= (*ct
>> 1) ^ (-(*ct
& 1) & ZFS_CRC64_POLY
);
873 for (i
= 0; i
< BUF_LOCKS
; i
++) {
874 mutex_init(&buf_hash_table
.ht_locks
[i
].ht_lock
,
875 NULL
, MUTEX_DEFAULT
, NULL
);
879 #define ARC_MINTIME (hz>>4) /* 62 ms */
882 arc_cksum_verify(arc_buf_t
*buf
)
886 if (!(zfs_flags
& ZFS_DEBUG_MODIFY
))
889 mutex_enter(&buf
->b_hdr
->b_freeze_lock
);
890 if (buf
->b_hdr
->b_freeze_cksum
== NULL
||
891 (buf
->b_hdr
->b_flags
& ARC_IO_ERROR
)) {
892 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
895 fletcher_2_native(buf
->b_data
, buf
->b_hdr
->b_size
, &zc
);
896 if (!ZIO_CHECKSUM_EQUAL(*buf
->b_hdr
->b_freeze_cksum
, zc
))
897 panic("buffer modified while frozen!");
898 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
902 arc_cksum_equal(arc_buf_t
*buf
)
907 mutex_enter(&buf
->b_hdr
->b_freeze_lock
);
908 fletcher_2_native(buf
->b_data
, buf
->b_hdr
->b_size
, &zc
);
909 equal
= ZIO_CHECKSUM_EQUAL(*buf
->b_hdr
->b_freeze_cksum
, zc
);
910 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
916 arc_cksum_compute(arc_buf_t
*buf
, boolean_t force
)
918 if (!force
&& !(zfs_flags
& ZFS_DEBUG_MODIFY
))
921 mutex_enter(&buf
->b_hdr
->b_freeze_lock
);
922 if (buf
->b_hdr
->b_freeze_cksum
!= NULL
) {
923 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
926 buf
->b_hdr
->b_freeze_cksum
= kmem_alloc(sizeof (zio_cksum_t
), KM_SLEEP
);
927 fletcher_2_native(buf
->b_data
, buf
->b_hdr
->b_size
,
928 buf
->b_hdr
->b_freeze_cksum
);
929 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
933 arc_buf_thaw(arc_buf_t
*buf
)
935 if (zfs_flags
& ZFS_DEBUG_MODIFY
) {
936 if (buf
->b_hdr
->b_state
!= arc_anon
)
937 panic("modifying non-anon buffer!");
938 if (buf
->b_hdr
->b_flags
& ARC_IO_IN_PROGRESS
)
939 panic("modifying buffer while i/o in progress!");
940 arc_cksum_verify(buf
);
943 mutex_enter(&buf
->b_hdr
->b_freeze_lock
);
944 if (buf
->b_hdr
->b_freeze_cksum
!= NULL
) {
945 kmem_free(buf
->b_hdr
->b_freeze_cksum
, sizeof (zio_cksum_t
));
946 buf
->b_hdr
->b_freeze_cksum
= NULL
;
948 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
952 arc_buf_freeze(arc_buf_t
*buf
)
954 if (!(zfs_flags
& ZFS_DEBUG_MODIFY
))
957 ASSERT(buf
->b_hdr
->b_freeze_cksum
!= NULL
||
958 buf
->b_hdr
->b_state
== arc_anon
);
959 arc_cksum_compute(buf
, B_FALSE
);
963 add_reference(arc_buf_hdr_t
*ab
, kmutex_t
*hash_lock
, void *tag
)
965 ASSERT(MUTEX_HELD(hash_lock
));
967 if ((refcount_add(&ab
->b_refcnt
, tag
) == 1) &&
968 (ab
->b_state
!= arc_anon
)) {
969 uint64_t delta
= ab
->b_size
* ab
->b_datacnt
;
970 list_t
*list
= &ab
->b_state
->arcs_list
[ab
->b_type
];
971 uint64_t *size
= &ab
->b_state
->arcs_lsize
[ab
->b_type
];
973 ASSERT(!MUTEX_HELD(&ab
->b_state
->arcs_mtx
));
974 mutex_enter(&ab
->b_state
->arcs_mtx
);
975 ASSERT(list_link_active(&ab
->b_arc_node
));
976 list_remove(list
, ab
);
977 if (GHOST_STATE(ab
->b_state
)) {
978 ASSERT3U(ab
->b_datacnt
, ==, 0);
979 ASSERT3P(ab
->b_buf
, ==, NULL
);
983 ASSERT3U(*size
, >=, delta
);
984 atomic_add_64(size
, -delta
);
985 mutex_exit(&ab
->b_state
->arcs_mtx
);
986 /* remove the prefetch flag if we get a reference */
987 if (ab
->b_flags
& ARC_PREFETCH
)
988 ab
->b_flags
&= ~ARC_PREFETCH
;
993 remove_reference(arc_buf_hdr_t
*ab
, kmutex_t
*hash_lock
, void *tag
)
996 arc_state_t
*state
= ab
->b_state
;
998 ASSERT(state
== arc_anon
|| MUTEX_HELD(hash_lock
));
999 ASSERT(!GHOST_STATE(state
));
1001 if (((cnt
= refcount_remove(&ab
->b_refcnt
, tag
)) == 0) &&
1002 (state
!= arc_anon
)) {
1003 uint64_t *size
= &state
->arcs_lsize
[ab
->b_type
];
1005 ASSERT(!MUTEX_HELD(&state
->arcs_mtx
));
1006 mutex_enter(&state
->arcs_mtx
);
1007 ASSERT(!list_link_active(&ab
->b_arc_node
));
1008 list_insert_head(&state
->arcs_list
[ab
->b_type
], ab
);
1009 ASSERT(ab
->b_datacnt
> 0);
1010 atomic_add_64(size
, ab
->b_size
* ab
->b_datacnt
);
1011 mutex_exit(&state
->arcs_mtx
);
1017 * Move the supplied buffer to the indicated state. The mutex
1018 * for the buffer must be held by the caller.
1021 arc_change_state(arc_state_t
*new_state
, arc_buf_hdr_t
*ab
, kmutex_t
*hash_lock
)
1023 arc_state_t
*old_state
= ab
->b_state
;
1024 int64_t refcnt
= refcount_count(&ab
->b_refcnt
);
1025 uint64_t from_delta
, to_delta
;
1027 ASSERT(MUTEX_HELD(hash_lock
));
1028 ASSERT(new_state
!= old_state
);
1029 ASSERT(refcnt
== 0 || ab
->b_datacnt
> 0);
1030 ASSERT(ab
->b_datacnt
== 0 || !GHOST_STATE(new_state
));
1032 from_delta
= to_delta
= ab
->b_datacnt
* ab
->b_size
;
1035 * If this buffer is evictable, transfer it from the
1036 * old state list to the new state list.
1039 if (old_state
!= arc_anon
) {
1040 int use_mutex
= !MUTEX_HELD(&old_state
->arcs_mtx
);
1041 uint64_t *size
= &old_state
->arcs_lsize
[ab
->b_type
];
1044 mutex_enter(&old_state
->arcs_mtx
);
1046 ASSERT(list_link_active(&ab
->b_arc_node
));
1047 list_remove(&old_state
->arcs_list
[ab
->b_type
], ab
);
1050 * If prefetching out of the ghost cache,
1051 * we will have a non-null datacnt.
1053 if (GHOST_STATE(old_state
) && ab
->b_datacnt
== 0) {
1054 /* ghost elements have a ghost size */
1055 ASSERT(ab
->b_buf
== NULL
);
1056 from_delta
= ab
->b_size
;
1058 ASSERT3U(*size
, >=, from_delta
);
1059 atomic_add_64(size
, -from_delta
);
1062 mutex_exit(&old_state
->arcs_mtx
);
1064 if (new_state
!= arc_anon
) {
1065 int use_mutex
= !MUTEX_HELD(&new_state
->arcs_mtx
);
1066 uint64_t *size
= &new_state
->arcs_lsize
[ab
->b_type
];
1069 mutex_enter(&new_state
->arcs_mtx
);
1071 list_insert_head(&new_state
->arcs_list
[ab
->b_type
], ab
);
1073 /* ghost elements have a ghost size */
1074 if (GHOST_STATE(new_state
)) {
1075 ASSERT(ab
->b_datacnt
== 0);
1076 ASSERT(ab
->b_buf
== NULL
);
1077 to_delta
= ab
->b_size
;
1079 atomic_add_64(size
, to_delta
);
1082 mutex_exit(&new_state
->arcs_mtx
);
1086 ASSERT(!BUF_EMPTY(ab
));
1087 if (new_state
== arc_anon
) {
1088 buf_hash_remove(ab
);
1091 /* adjust state sizes */
1093 atomic_add_64(&new_state
->arcs_size
, to_delta
);
1095 ASSERT3U(old_state
->arcs_size
, >=, from_delta
);
1096 atomic_add_64(&old_state
->arcs_size
, -from_delta
);
1098 ab
->b_state
= new_state
;
1100 /* adjust l2arc hdr stats */
1101 if (new_state
== arc_l2c_only
)
1102 l2arc_hdr_stat_add();
1103 else if (old_state
== arc_l2c_only
)
1104 l2arc_hdr_stat_remove();
1108 arc_space_consume(uint64_t space
, arc_space_type_t type
)
1110 ASSERT(type
>= 0 && type
< ARC_SPACE_NUMTYPES
);
1113 case ARC_SPACE_DATA
:
1114 ARCSTAT_INCR(arcstat_data_size
, space
);
1116 case ARC_SPACE_OTHER
:
1117 ARCSTAT_INCR(arcstat_other_size
, space
);
1119 case ARC_SPACE_HDRS
:
1120 ARCSTAT_INCR(arcstat_hdr_size
, space
);
1122 case ARC_SPACE_L2HDRS
:
1123 ARCSTAT_INCR(arcstat_l2_hdr_size
, space
);
1127 atomic_add_64(&arc_meta_used
, space
);
1128 atomic_add_64(&arc_size
, space
);
1132 arc_space_return(uint64_t space
, arc_space_type_t type
)
1134 ASSERT(type
>= 0 && type
< ARC_SPACE_NUMTYPES
);
1137 case ARC_SPACE_DATA
:
1138 ARCSTAT_INCR(arcstat_data_size
, -space
);
1140 case ARC_SPACE_OTHER
:
1141 ARCSTAT_INCR(arcstat_other_size
, -space
);
1143 case ARC_SPACE_HDRS
:
1144 ARCSTAT_INCR(arcstat_hdr_size
, -space
);
1146 case ARC_SPACE_L2HDRS
:
1147 ARCSTAT_INCR(arcstat_l2_hdr_size
, -space
);
1151 ASSERT(arc_meta_used
>= space
);
1152 if (arc_meta_max
< arc_meta_used
)
1153 arc_meta_max
= arc_meta_used
;
1154 atomic_add_64(&arc_meta_used
, -space
);
1155 ASSERT(arc_size
>= space
);
1156 atomic_add_64(&arc_size
, -space
);
1160 arc_data_buf_alloc(uint64_t size
)
1162 if (arc_evict_needed(ARC_BUFC_DATA
))
1163 cv_signal(&arc_reclaim_thr_cv
);
1164 atomic_add_64(&arc_size
, size
);
1165 return (zio_data_buf_alloc(size
));
1169 arc_data_buf_free(void *buf
, uint64_t size
)
1171 zio_data_buf_free(buf
, size
);
1172 ASSERT(arc_size
>= size
);
1173 atomic_add_64(&arc_size
, -size
);
1177 arc_buf_alloc(spa_t
*spa
, int size
, void *tag
, arc_buf_contents_t type
)
1182 ASSERT3U(size
, >, 0);
1183 hdr
= kmem_cache_alloc(hdr_cache
, KM_PUSHPAGE
);
1184 ASSERT(BUF_EMPTY(hdr
));
1187 hdr
->b_spa
= spa_guid(spa
);
1188 hdr
->b_state
= arc_anon
;
1189 hdr
->b_arc_access
= 0;
1190 buf
= kmem_cache_alloc(buf_cache
, KM_PUSHPAGE
);
1193 buf
->b_efunc
= NULL
;
1194 buf
->b_private
= NULL
;
1197 arc_get_data_buf(buf
);
1200 ASSERT(refcount_is_zero(&hdr
->b_refcnt
));
1201 (void) refcount_add(&hdr
->b_refcnt
, tag
);
1207 arc_buf_clone(arc_buf_t
*from
)
1210 arc_buf_hdr_t
*hdr
= from
->b_hdr
;
1211 uint64_t size
= hdr
->b_size
;
1213 buf
= kmem_cache_alloc(buf_cache
, KM_PUSHPAGE
);
1216 buf
->b_efunc
= NULL
;
1217 buf
->b_private
= NULL
;
1218 buf
->b_next
= hdr
->b_buf
;
1220 arc_get_data_buf(buf
);
1221 bcopy(from
->b_data
, buf
->b_data
, size
);
1222 hdr
->b_datacnt
+= 1;
1227 arc_buf_add_ref(arc_buf_t
*buf
, void* tag
)
1230 kmutex_t
*hash_lock
;
1233 * Check to see if this buffer is evicted. Callers
1234 * must verify b_data != NULL to know if the add_ref
1237 rw_enter(&buf
->b_lock
, RW_READER
);
1238 if (buf
->b_data
== NULL
) {
1239 rw_exit(&buf
->b_lock
);
1243 ASSERT(hdr
!= NULL
);
1244 hash_lock
= HDR_LOCK(hdr
);
1245 mutex_enter(hash_lock
);
1246 rw_exit(&buf
->b_lock
);
1248 ASSERT(hdr
->b_state
== arc_mru
|| hdr
->b_state
== arc_mfu
);
1249 add_reference(hdr
, hash_lock
, tag
);
1250 DTRACE_PROBE1(arc__hit
, arc_buf_hdr_t
*, hdr
);
1251 arc_access(hdr
, hash_lock
);
1252 mutex_exit(hash_lock
);
1253 ARCSTAT_BUMP(arcstat_hits
);
1254 ARCSTAT_CONDSTAT(!(hdr
->b_flags
& ARC_PREFETCH
),
1255 demand
, prefetch
, hdr
->b_type
!= ARC_BUFC_METADATA
,
1256 data
, metadata
, hits
);
1260 * Free the arc data buffer. If it is an l2arc write in progress,
1261 * the buffer is placed on l2arc_free_on_write to be freed later.
1264 arc_buf_data_free(arc_buf_hdr_t
*hdr
, void (*free_func
)(void *, size_t),
1265 void *data
, size_t size
)
1267 if (HDR_L2_WRITING(hdr
)) {
1268 l2arc_data_free_t
*df
;
1269 df
= kmem_alloc(sizeof (l2arc_data_free_t
), KM_SLEEP
);
1270 df
->l2df_data
= data
;
1271 df
->l2df_size
= size
;
1272 df
->l2df_func
= free_func
;
1273 mutex_enter(&l2arc_free_on_write_mtx
);
1274 list_insert_head(l2arc_free_on_write
, df
);
1275 mutex_exit(&l2arc_free_on_write_mtx
);
1276 ARCSTAT_BUMP(arcstat_l2_free_on_write
);
1278 free_func(data
, size
);
1283 arc_buf_destroy(arc_buf_t
*buf
, boolean_t recycle
, boolean_t all
)
1287 /* free up data associated with the buf */
1289 arc_state_t
*state
= buf
->b_hdr
->b_state
;
1290 uint64_t size
= buf
->b_hdr
->b_size
;
1291 arc_buf_contents_t type
= buf
->b_hdr
->b_type
;
1293 arc_cksum_verify(buf
);
1295 if (type
== ARC_BUFC_METADATA
) {
1296 arc_buf_data_free(buf
->b_hdr
, zio_buf_free
,
1298 arc_space_return(size
, ARC_SPACE_DATA
);
1300 ASSERT(type
== ARC_BUFC_DATA
);
1301 arc_buf_data_free(buf
->b_hdr
,
1302 zio_data_buf_free
, buf
->b_data
, size
);
1303 ARCSTAT_INCR(arcstat_data_size
, -size
);
1304 atomic_add_64(&arc_size
, -size
);
1307 if (list_link_active(&buf
->b_hdr
->b_arc_node
)) {
1308 uint64_t *cnt
= &state
->arcs_lsize
[type
];
1310 ASSERT(refcount_is_zero(&buf
->b_hdr
->b_refcnt
));
1311 ASSERT(state
!= arc_anon
);
1313 ASSERT3U(*cnt
, >=, size
);
1314 atomic_add_64(cnt
, -size
);
1316 ASSERT3U(state
->arcs_size
, >=, size
);
1317 atomic_add_64(&state
->arcs_size
, -size
);
1319 ASSERT(buf
->b_hdr
->b_datacnt
> 0);
1320 buf
->b_hdr
->b_datacnt
-= 1;
1323 /* only remove the buf if requested */
1327 /* remove the buf from the hdr list */
1328 for (bufp
= &buf
->b_hdr
->b_buf
; *bufp
!= buf
; bufp
= &(*bufp
)->b_next
)
1330 *bufp
= buf
->b_next
;
1332 ASSERT(buf
->b_efunc
== NULL
);
1334 /* clean up the buf */
1336 kmem_cache_free(buf_cache
, buf
);
1340 arc_hdr_destroy(arc_buf_hdr_t
*hdr
)
1342 ASSERT(refcount_is_zero(&hdr
->b_refcnt
));
1343 ASSERT3P(hdr
->b_state
, ==, arc_anon
);
1344 ASSERT(!HDR_IO_IN_PROGRESS(hdr
));
1345 ASSERT(!(hdr
->b_flags
& ARC_STORED
));
1347 if (hdr
->b_l2hdr
!= NULL
) {
1348 if (!MUTEX_HELD(&l2arc_buflist_mtx
)) {
1350 * To prevent arc_free() and l2arc_evict() from
1351 * attempting to free the same buffer at the same time,
1352 * a FREE_IN_PROGRESS flag is given to arc_free() to
1353 * give it priority. l2arc_evict() can't destroy this
1354 * header while we are waiting on l2arc_buflist_mtx.
1356 * The hdr may be removed from l2ad_buflist before we
1357 * grab l2arc_buflist_mtx, so b_l2hdr is rechecked.
1359 mutex_enter(&l2arc_buflist_mtx
);
1360 if (hdr
->b_l2hdr
!= NULL
) {
1361 list_remove(hdr
->b_l2hdr
->b_dev
->l2ad_buflist
,
1364 mutex_exit(&l2arc_buflist_mtx
);
1366 list_remove(hdr
->b_l2hdr
->b_dev
->l2ad_buflist
, hdr
);
1368 ARCSTAT_INCR(arcstat_l2_size
, -hdr
->b_size
);
1369 kmem_free(hdr
->b_l2hdr
, sizeof (l2arc_buf_hdr_t
));
1370 if (hdr
->b_state
== arc_l2c_only
)
1371 l2arc_hdr_stat_remove();
1372 hdr
->b_l2hdr
= NULL
;
1375 if (!BUF_EMPTY(hdr
)) {
1376 ASSERT(!HDR_IN_HASH_TABLE(hdr
));
1377 bzero(&hdr
->b_dva
, sizeof (dva_t
));
1381 while (hdr
->b_buf
) {
1382 arc_buf_t
*buf
= hdr
->b_buf
;
1385 mutex_enter(&arc_eviction_mtx
);
1386 rw_enter(&buf
->b_lock
, RW_WRITER
);
1387 ASSERT(buf
->b_hdr
!= NULL
);
1388 arc_buf_destroy(hdr
->b_buf
, FALSE
, FALSE
);
1389 hdr
->b_buf
= buf
->b_next
;
1390 buf
->b_hdr
= &arc_eviction_hdr
;
1391 buf
->b_next
= arc_eviction_list
;
1392 arc_eviction_list
= buf
;
1393 rw_exit(&buf
->b_lock
);
1394 mutex_exit(&arc_eviction_mtx
);
1396 arc_buf_destroy(hdr
->b_buf
, FALSE
, TRUE
);
1399 if (hdr
->b_freeze_cksum
!= NULL
) {
1400 kmem_free(hdr
->b_freeze_cksum
, sizeof (zio_cksum_t
));
1401 hdr
->b_freeze_cksum
= NULL
;
1404 ASSERT(!list_link_active(&hdr
->b_arc_node
));
1405 ASSERT3P(hdr
->b_hash_next
, ==, NULL
);
1406 ASSERT3P(hdr
->b_acb
, ==, NULL
);
1407 kmem_cache_free(hdr_cache
, hdr
);
1411 arc_buf_free(arc_buf_t
*buf
, void *tag
)
1413 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
1414 int hashed
= hdr
->b_state
!= arc_anon
;
1416 ASSERT(buf
->b_efunc
== NULL
);
1417 ASSERT(buf
->b_data
!= NULL
);
1420 kmutex_t
*hash_lock
= HDR_LOCK(hdr
);
1422 mutex_enter(hash_lock
);
1423 (void) remove_reference(hdr
, hash_lock
, tag
);
1424 if (hdr
->b_datacnt
> 1)
1425 arc_buf_destroy(buf
, FALSE
, TRUE
);
1427 hdr
->b_flags
|= ARC_BUF_AVAILABLE
;
1428 mutex_exit(hash_lock
);
1429 } else if (HDR_IO_IN_PROGRESS(hdr
)) {
1432 * We are in the middle of an async write. Don't destroy
1433 * this buffer unless the write completes before we finish
1434 * decrementing the reference count.
1436 mutex_enter(&arc_eviction_mtx
);
1437 (void) remove_reference(hdr
, NULL
, tag
);
1438 ASSERT(refcount_is_zero(&hdr
->b_refcnt
));
1439 destroy_hdr
= !HDR_IO_IN_PROGRESS(hdr
);
1440 mutex_exit(&arc_eviction_mtx
);
1442 arc_hdr_destroy(hdr
);
1444 if (remove_reference(hdr
, NULL
, tag
) > 0) {
1445 ASSERT(HDR_IO_ERROR(hdr
));
1446 arc_buf_destroy(buf
, FALSE
, TRUE
);
1448 arc_hdr_destroy(hdr
);
1454 arc_buf_remove_ref(arc_buf_t
*buf
, void* tag
)
1456 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
1457 kmutex_t
*hash_lock
= HDR_LOCK(hdr
);
1458 int no_callback
= (buf
->b_efunc
== NULL
);
1460 if (hdr
->b_state
== arc_anon
) {
1461 arc_buf_free(buf
, tag
);
1462 return (no_callback
);
1465 mutex_enter(hash_lock
);
1466 ASSERT(hdr
->b_state
!= arc_anon
);
1467 ASSERT(buf
->b_data
!= NULL
);
1469 (void) remove_reference(hdr
, hash_lock
, tag
);
1470 if (hdr
->b_datacnt
> 1) {
1472 arc_buf_destroy(buf
, FALSE
, TRUE
);
1473 } else if (no_callback
) {
1474 ASSERT(hdr
->b_buf
== buf
&& buf
->b_next
== NULL
);
1475 hdr
->b_flags
|= ARC_BUF_AVAILABLE
;
1477 ASSERT(no_callback
|| hdr
->b_datacnt
> 1 ||
1478 refcount_is_zero(&hdr
->b_refcnt
));
1479 mutex_exit(hash_lock
);
1480 return (no_callback
);
1484 arc_buf_size(arc_buf_t
*buf
)
1486 return (buf
->b_hdr
->b_size
);
1490 * Evict buffers from list until we've removed the specified number of
1491 * bytes. Move the removed buffers to the appropriate evict state.
1492 * If the recycle flag is set, then attempt to "recycle" a buffer:
1493 * - look for a buffer to evict that is `bytes' long.
1494 * - return the data block from this buffer rather than freeing it.
1495 * This flag is used by callers that are trying to make space for a
1496 * new buffer in a full arc cache.
1498 * This function makes a "best effort". It skips over any buffers
1499 * it can't get a hash_lock on, and so may not catch all candidates.
1500 * It may also return without evicting as much space as requested.
1503 arc_evict(arc_state_t
*state
, uint64_t spa
, int64_t bytes
, boolean_t recycle
,
1504 arc_buf_contents_t type
)
1506 arc_state_t
*evicted_state
;
1507 uint64_t bytes_evicted
= 0, skipped
= 0, missed
= 0;
1508 arc_buf_hdr_t
*ab
, *ab_prev
= NULL
;
1509 list_t
*list
= &state
->arcs_list
[type
];
1510 kmutex_t
*hash_lock
;
1511 boolean_t have_lock
;
1512 void *stolen
= NULL
;
1514 ASSERT(state
== arc_mru
|| state
== arc_mfu
);
1516 evicted_state
= (state
== arc_mru
) ? arc_mru_ghost
: arc_mfu_ghost
;
1518 mutex_enter(&state
->arcs_mtx
);
1519 mutex_enter(&evicted_state
->arcs_mtx
);
1521 for (ab
= list_tail(list
); ab
; ab
= ab_prev
) {
1522 ab_prev
= list_prev(list
, ab
);
1523 /* prefetch buffers have a minimum lifespan */
1524 if (HDR_IO_IN_PROGRESS(ab
) ||
1525 (spa
&& ab
->b_spa
!= spa
) ||
1526 (ab
->b_flags
& (ARC_PREFETCH
|ARC_INDIRECT
) &&
1527 lbolt
- ab
->b_arc_access
< arc_min_prefetch_lifespan
)) {
1531 /* "lookahead" for better eviction candidate */
1532 if (recycle
&& ab
->b_size
!= bytes
&&
1533 ab_prev
&& ab_prev
->b_size
== bytes
)
1535 hash_lock
= HDR_LOCK(ab
);
1536 have_lock
= MUTEX_HELD(hash_lock
);
1537 if (have_lock
|| mutex_tryenter(hash_lock
)) {
1538 ASSERT3U(refcount_count(&ab
->b_refcnt
), ==, 0);
1539 ASSERT(ab
->b_datacnt
> 0);
1541 arc_buf_t
*buf
= ab
->b_buf
;
1542 if (!rw_tryenter(&buf
->b_lock
, RW_WRITER
)) {
1547 bytes_evicted
+= ab
->b_size
;
1548 if (recycle
&& ab
->b_type
== type
&&
1549 ab
->b_size
== bytes
&&
1550 !HDR_L2_WRITING(ab
)) {
1551 stolen
= buf
->b_data
;
1556 mutex_enter(&arc_eviction_mtx
);
1557 arc_buf_destroy(buf
,
1558 buf
->b_data
== stolen
, FALSE
);
1559 ab
->b_buf
= buf
->b_next
;
1560 buf
->b_hdr
= &arc_eviction_hdr
;
1561 buf
->b_next
= arc_eviction_list
;
1562 arc_eviction_list
= buf
;
1563 mutex_exit(&arc_eviction_mtx
);
1564 rw_exit(&buf
->b_lock
);
1566 rw_exit(&buf
->b_lock
);
1567 arc_buf_destroy(buf
,
1568 buf
->b_data
== stolen
, TRUE
);
1571 if (ab
->b_datacnt
== 0) {
1572 arc_change_state(evicted_state
, ab
, hash_lock
);
1573 ASSERT(HDR_IN_HASH_TABLE(ab
));
1574 ab
->b_flags
|= ARC_IN_HASH_TABLE
;
1575 ab
->b_flags
&= ~ARC_BUF_AVAILABLE
;
1576 DTRACE_PROBE1(arc__evict
, arc_buf_hdr_t
*, ab
);
1579 mutex_exit(hash_lock
);
1580 if (bytes
>= 0 && bytes_evicted
>= bytes
)
1587 mutex_exit(&evicted_state
->arcs_mtx
);
1588 mutex_exit(&state
->arcs_mtx
);
1590 if (bytes_evicted
< bytes
)
1591 dprintf("only evicted %lld bytes from %x",
1592 (longlong_t
)bytes_evicted
, state
);
1595 ARCSTAT_INCR(arcstat_evict_skip
, skipped
);
1598 ARCSTAT_INCR(arcstat_mutex_miss
, missed
);
1601 * We have just evicted some date into the ghost state, make
1602 * sure we also adjust the ghost state size if necessary.
1605 arc_mru_ghost
->arcs_size
+ arc_mfu_ghost
->arcs_size
> arc_c
) {
1606 int64_t mru_over
= arc_anon
->arcs_size
+ arc_mru
->arcs_size
+
1607 arc_mru_ghost
->arcs_size
- arc_c
;
1609 if (mru_over
> 0 && arc_mru_ghost
->arcs_lsize
[type
] > 0) {
1611 MIN(arc_mru_ghost
->arcs_lsize
[type
], mru_over
);
1612 arc_evict_ghost(arc_mru_ghost
, NULL
, todelete
);
1613 } else if (arc_mfu_ghost
->arcs_lsize
[type
] > 0) {
1614 int64_t todelete
= MIN(arc_mfu_ghost
->arcs_lsize
[type
],
1615 arc_mru_ghost
->arcs_size
+
1616 arc_mfu_ghost
->arcs_size
- arc_c
);
1617 arc_evict_ghost(arc_mfu_ghost
, NULL
, todelete
);
1625 * Remove buffers from list until we've removed the specified number of
1626 * bytes. Destroy the buffers that are removed.
1629 arc_evict_ghost(arc_state_t
*state
, uint64_t spa
, int64_t bytes
)
1631 arc_buf_hdr_t
*ab
, *ab_prev
;
1632 list_t
*list
= &state
->arcs_list
[ARC_BUFC_DATA
];
1633 kmutex_t
*hash_lock
;
1634 uint64_t bytes_deleted
= 0;
1635 uint64_t bufs_skipped
= 0;
1637 ASSERT(GHOST_STATE(state
));
1639 mutex_enter(&state
->arcs_mtx
);
1640 for (ab
= list_tail(list
); ab
; ab
= ab_prev
) {
1641 ab_prev
= list_prev(list
, ab
);
1642 if (spa
&& ab
->b_spa
!= spa
)
1644 hash_lock
= HDR_LOCK(ab
);
1645 if (mutex_tryenter(hash_lock
)) {
1646 ASSERT(!HDR_IO_IN_PROGRESS(ab
));
1647 ASSERT(ab
->b_buf
== NULL
);
1648 ARCSTAT_BUMP(arcstat_deleted
);
1649 bytes_deleted
+= ab
->b_size
;
1651 if (ab
->b_l2hdr
!= NULL
) {
1653 * This buffer is cached on the 2nd Level ARC;
1654 * don't destroy the header.
1656 arc_change_state(arc_l2c_only
, ab
, hash_lock
);
1657 mutex_exit(hash_lock
);
1659 arc_change_state(arc_anon
, ab
, hash_lock
);
1660 mutex_exit(hash_lock
);
1661 arc_hdr_destroy(ab
);
1664 DTRACE_PROBE1(arc__delete
, arc_buf_hdr_t
*, ab
);
1665 if (bytes
>= 0 && bytes_deleted
>= bytes
)
1669 mutex_exit(&state
->arcs_mtx
);
1670 mutex_enter(hash_lock
);
1671 mutex_exit(hash_lock
);
1677 mutex_exit(&state
->arcs_mtx
);
1679 if (list
== &state
->arcs_list
[ARC_BUFC_DATA
] &&
1680 (bytes
< 0 || bytes_deleted
< bytes
)) {
1681 list
= &state
->arcs_list
[ARC_BUFC_METADATA
];
1686 ARCSTAT_INCR(arcstat_mutex_miss
, bufs_skipped
);
1690 if (bytes_deleted
< bytes
)
1691 dprintf("only deleted %lld bytes from %p",
1692 (longlong_t
)bytes_deleted
, state
);
1698 int64_t adjustment
, delta
;
1704 adjustment
= MIN(arc_size
- arc_c
,
1705 arc_anon
->arcs_size
+ arc_mru
->arcs_size
+ arc_meta_used
- arc_p
);
1707 if (adjustment
> 0 && arc_mru
->arcs_lsize
[ARC_BUFC_DATA
] > 0) {
1708 delta
= MIN(arc_mru
->arcs_lsize
[ARC_BUFC_DATA
], adjustment
);
1709 (void) arc_evict(arc_mru
, NULL
, delta
, FALSE
, ARC_BUFC_DATA
);
1710 adjustment
-= delta
;
1713 if (adjustment
> 0 && arc_mru
->arcs_lsize
[ARC_BUFC_METADATA
] > 0) {
1714 delta
= MIN(arc_mru
->arcs_lsize
[ARC_BUFC_METADATA
], adjustment
);
1715 (void) arc_evict(arc_mru
, NULL
, delta
, FALSE
,
1723 adjustment
= arc_size
- arc_c
;
1725 if (adjustment
> 0 && arc_mfu
->arcs_lsize
[ARC_BUFC_DATA
] > 0) {
1726 delta
= MIN(adjustment
, arc_mfu
->arcs_lsize
[ARC_BUFC_DATA
]);
1727 (void) arc_evict(arc_mfu
, NULL
, delta
, FALSE
, ARC_BUFC_DATA
);
1728 adjustment
-= delta
;
1731 if (adjustment
> 0 && arc_mfu
->arcs_lsize
[ARC_BUFC_METADATA
] > 0) {
1732 int64_t delta
= MIN(adjustment
,
1733 arc_mfu
->arcs_lsize
[ARC_BUFC_METADATA
]);
1734 (void) arc_evict(arc_mfu
, NULL
, delta
, FALSE
,
1739 * Adjust ghost lists
1742 adjustment
= arc_mru
->arcs_size
+ arc_mru_ghost
->arcs_size
- arc_c
;
1744 if (adjustment
> 0 && arc_mru_ghost
->arcs_size
> 0) {
1745 delta
= MIN(arc_mru_ghost
->arcs_size
, adjustment
);
1746 arc_evict_ghost(arc_mru_ghost
, NULL
, delta
);
1750 arc_mru_ghost
->arcs_size
+ arc_mfu_ghost
->arcs_size
- arc_c
;
1752 if (adjustment
> 0 && arc_mfu_ghost
->arcs_size
> 0) {
1753 delta
= MIN(arc_mfu_ghost
->arcs_size
, adjustment
);
1754 arc_evict_ghost(arc_mfu_ghost
, NULL
, delta
);
1759 arc_do_user_evicts(void)
1761 mutex_enter(&arc_eviction_mtx
);
1762 while (arc_eviction_list
!= NULL
) {
1763 arc_buf_t
*buf
= arc_eviction_list
;
1764 arc_eviction_list
= buf
->b_next
;
1765 rw_enter(&buf
->b_lock
, RW_WRITER
);
1767 rw_exit(&buf
->b_lock
);
1768 mutex_exit(&arc_eviction_mtx
);
1770 if (buf
->b_efunc
!= NULL
)
1771 VERIFY(buf
->b_efunc(buf
) == 0);
1773 buf
->b_efunc
= NULL
;
1774 buf
->b_private
= NULL
;
1775 kmem_cache_free(buf_cache
, buf
);
1776 mutex_enter(&arc_eviction_mtx
);
1778 mutex_exit(&arc_eviction_mtx
);
1782 * Flush all *evictable* data from the cache for the given spa.
1783 * NOTE: this will not touch "active" (i.e. referenced) data.
1786 arc_flush(spa_t
*spa
)
1791 guid
= spa_guid(spa
);
1793 while (list_head(&arc_mru
->arcs_list
[ARC_BUFC_DATA
])) {
1794 (void) arc_evict(arc_mru
, guid
, -1, FALSE
, ARC_BUFC_DATA
);
1798 while (list_head(&arc_mru
->arcs_list
[ARC_BUFC_METADATA
])) {
1799 (void) arc_evict(arc_mru
, guid
, -1, FALSE
, ARC_BUFC_METADATA
);
1803 while (list_head(&arc_mfu
->arcs_list
[ARC_BUFC_DATA
])) {
1804 (void) arc_evict(arc_mfu
, guid
, -1, FALSE
, ARC_BUFC_DATA
);
1808 while (list_head(&arc_mfu
->arcs_list
[ARC_BUFC_METADATA
])) {
1809 (void) arc_evict(arc_mfu
, guid
, -1, FALSE
, ARC_BUFC_METADATA
);
1814 arc_evict_ghost(arc_mru_ghost
, guid
, -1);
1815 arc_evict_ghost(arc_mfu_ghost
, guid
, -1);
1817 mutex_enter(&arc_reclaim_thr_lock
);
1818 arc_do_user_evicts();
1819 mutex_exit(&arc_reclaim_thr_lock
);
1820 ASSERT(spa
|| arc_eviction_list
== NULL
);
1826 if (arc_c
> arc_c_min
) {
1830 to_free
= MAX(arc_c
>> arc_shrink_shift
, ptob(needfree
));
1832 to_free
= arc_c
>> arc_shrink_shift
;
1834 if (arc_c
> arc_c_min
+ to_free
)
1835 atomic_add_64(&arc_c
, -to_free
);
1839 atomic_add_64(&arc_p
, -(arc_p
>> arc_shrink_shift
));
1840 if (arc_c
> arc_size
)
1841 arc_c
= MAX(arc_size
, arc_c_min
);
1843 arc_p
= (arc_c
>> 1);
1844 ASSERT(arc_c
>= arc_c_min
);
1845 ASSERT((int64_t)arc_p
>= 0);
1848 if (arc_size
> arc_c
)
1853 arc_reclaim_needed(void)
1863 * take 'desfree' extra pages, so we reclaim sooner, rather than later
1868 * check that we're out of range of the pageout scanner. It starts to
1869 * schedule paging if freemem is less than lotsfree and needfree.
1870 * lotsfree is the high-water mark for pageout, and needfree is the
1871 * number of needed free pages. We add extra pages here to make sure
1872 * the scanner doesn't start up while we're freeing memory.
1874 if (freemem
< lotsfree
+ needfree
+ extra
)
1878 * check to make sure that swapfs has enough space so that anon
1879 * reservations can still succeed. anon_resvmem() checks that the
1880 * availrmem is greater than swapfs_minfree, and the number of reserved
1881 * swap pages. We also add a bit of extra here just to prevent
1882 * circumstances from getting really dire.
1884 if (availrmem
< swapfs_minfree
+ swapfs_reserve
+ extra
)
1889 * If we're on an i386 platform, it's possible that we'll exhaust the
1890 * kernel heap space before we ever run out of available physical
1891 * memory. Most checks of the size of the heap_area compare against
1892 * tune.t_minarmem, which is the minimum available real memory that we
1893 * can have in the system. However, this is generally fixed at 25 pages
1894 * which is so low that it's useless. In this comparison, we seek to
1895 * calculate the total heap-size, and reclaim if more than 3/4ths of the
1896 * heap is allocated. (Or, in the calculation, if less than 1/4th is
1899 if (btop(vmem_size(heap_arena
, VMEM_FREE
)) <
1900 (btop(vmem_size(heap_arena
, VMEM_FREE
| VMEM_ALLOC
)) >> 2))
1905 if (spa_get_random(100) == 0)
1912 arc_kmem_reap_now(arc_reclaim_strategy_t strat
)
1915 kmem_cache_t
*prev_cache
= NULL
;
1916 kmem_cache_t
*prev_data_cache
= NULL
;
1917 extern kmem_cache_t
*zio_buf_cache
[];
1918 extern kmem_cache_t
*zio_data_buf_cache
[];
1921 if (arc_meta_used
>= arc_meta_limit
) {
1923 * We are exceeding our meta-data cache limit.
1924 * Purge some DNLC entries to release holds on meta-data.
1926 dnlc_reduce_cache((void *)(uintptr_t)arc_reduce_dnlc_percent
);
1930 * Reclaim unused memory from all kmem caches.
1937 * An aggressive reclamation will shrink the cache size as well as
1938 * reap free buffers from the arc kmem caches.
1940 if (strat
== ARC_RECLAIM_AGGR
)
1943 for (i
= 0; i
< SPA_MAXBLOCKSIZE
>> SPA_MINBLOCKSHIFT
; i
++) {
1944 if (zio_buf_cache
[i
] != prev_cache
) {
1945 prev_cache
= zio_buf_cache
[i
];
1946 kmem_cache_reap_now(zio_buf_cache
[i
]);
1948 if (zio_data_buf_cache
[i
] != prev_data_cache
) {
1949 prev_data_cache
= zio_data_buf_cache
[i
];
1950 kmem_cache_reap_now(zio_data_buf_cache
[i
]);
1953 kmem_cache_reap_now(buf_cache
);
1954 kmem_cache_reap_now(hdr_cache
);
1958 arc_reclaim_thread(void)
1960 clock_t growtime
= 0;
1961 arc_reclaim_strategy_t last_reclaim
= ARC_RECLAIM_CONS
;
1964 CALLB_CPR_INIT(&cpr
, &arc_reclaim_thr_lock
, callb_generic_cpr
, FTAG
);
1966 mutex_enter(&arc_reclaim_thr_lock
);
1967 while (arc_thread_exit
== 0) {
1968 if (arc_reclaim_needed()) {
1971 if (last_reclaim
== ARC_RECLAIM_CONS
) {
1972 last_reclaim
= ARC_RECLAIM_AGGR
;
1974 last_reclaim
= ARC_RECLAIM_CONS
;
1978 last_reclaim
= ARC_RECLAIM_AGGR
;
1982 /* reset the growth delay for every reclaim */
1983 growtime
= lbolt
+ (arc_grow_retry
* hz
);
1985 arc_kmem_reap_now(last_reclaim
);
1988 } else if (arc_no_grow
&& lbolt
>= growtime
) {
1989 arc_no_grow
= FALSE
;
1992 if (2 * arc_c
< arc_size
+
1993 arc_mru_ghost
->arcs_size
+ arc_mfu_ghost
->arcs_size
)
1996 if (arc_eviction_list
!= NULL
)
1997 arc_do_user_evicts();
1999 /* block until needed, or one second, whichever is shorter */
2000 CALLB_CPR_SAFE_BEGIN(&cpr
);
2001 (void) cv_timedwait(&arc_reclaim_thr_cv
,
2002 &arc_reclaim_thr_lock
, (lbolt
+ hz
));
2003 CALLB_CPR_SAFE_END(&cpr
, &arc_reclaim_thr_lock
);
2006 arc_thread_exit
= 0;
2007 cv_broadcast(&arc_reclaim_thr_cv
);
2008 CALLB_CPR_EXIT(&cpr
); /* drops arc_reclaim_thr_lock */
2013 * Adapt arc info given the number of bytes we are trying to add and
2014 * the state that we are comming from. This function is only called
2015 * when we are adding new content to the cache.
2018 arc_adapt(int bytes
, arc_state_t
*state
)
2021 uint64_t arc_p_min
= (arc_c
>> arc_p_min_shift
);
2023 if (state
== arc_l2c_only
)
2028 * Adapt the target size of the MRU list:
2029 * - if we just hit in the MRU ghost list, then increase
2030 * the target size of the MRU list.
2031 * - if we just hit in the MFU ghost list, then increase
2032 * the target size of the MFU list by decreasing the
2033 * target size of the MRU list.
2035 if (state
== arc_mru_ghost
) {
2036 mult
= ((arc_mru_ghost
->arcs_size
>= arc_mfu_ghost
->arcs_size
) ?
2037 1 : (arc_mfu_ghost
->arcs_size
/arc_mru_ghost
->arcs_size
));
2039 arc_p
= MIN(arc_c
- arc_p_min
, arc_p
+ bytes
* mult
);
2040 } else if (state
== arc_mfu_ghost
) {
2043 mult
= ((arc_mfu_ghost
->arcs_size
>= arc_mru_ghost
->arcs_size
) ?
2044 1 : (arc_mru_ghost
->arcs_size
/arc_mfu_ghost
->arcs_size
));
2046 delta
= MIN(bytes
* mult
, arc_p
);
2047 arc_p
= MAX(arc_p_min
, arc_p
- delta
);
2049 ASSERT((int64_t)arc_p
>= 0);
2051 if (arc_reclaim_needed()) {
2052 cv_signal(&arc_reclaim_thr_cv
);
2059 if (arc_c
>= arc_c_max
)
2063 * If we're within (2 * maxblocksize) bytes of the target
2064 * cache size, increment the target cache size
2066 if (arc_size
> arc_c
- (2ULL << SPA_MAXBLOCKSHIFT
)) {
2067 atomic_add_64(&arc_c
, (int64_t)bytes
);
2068 if (arc_c
> arc_c_max
)
2070 else if (state
== arc_anon
)
2071 atomic_add_64(&arc_p
, (int64_t)bytes
);
2075 ASSERT((int64_t)arc_p
>= 0);
2079 * Check if the cache has reached its limits and eviction is required
2083 arc_evict_needed(arc_buf_contents_t type
)
2085 if (type
== ARC_BUFC_METADATA
&& arc_meta_used
>= arc_meta_limit
)
2090 * If zio data pages are being allocated out of a separate heap segment,
2091 * then enforce that the size of available vmem for this area remains
2092 * above about 1/32nd free.
2094 if (type
== ARC_BUFC_DATA
&& zio_arena
!= NULL
&&
2095 vmem_size(zio_arena
, VMEM_FREE
) <
2096 (vmem_size(zio_arena
, VMEM_ALLOC
) >> 5))
2100 if (arc_reclaim_needed())
2103 return (arc_size
> arc_c
);
2107 * The buffer, supplied as the first argument, needs a data block.
2108 * So, if we are at cache max, determine which cache should be victimized.
2109 * We have the following cases:
2111 * 1. Insert for MRU, p > sizeof(arc_anon + arc_mru) ->
2112 * In this situation if we're out of space, but the resident size of the MFU is
2113 * under the limit, victimize the MFU cache to satisfy this insertion request.
2115 * 2. Insert for MRU, p <= sizeof(arc_anon + arc_mru) ->
2116 * Here, we've used up all of the available space for the MRU, so we need to
2117 * evict from our own cache instead. Evict from the set of resident MRU
2120 * 3. Insert for MFU (c - p) > sizeof(arc_mfu) ->
2121 * c minus p represents the MFU space in the cache, since p is the size of the
2122 * cache that is dedicated to the MRU. In this situation there's still space on
2123 * the MFU side, so the MRU side needs to be victimized.
2125 * 4. Insert for MFU (c - p) < sizeof(arc_mfu) ->
2126 * MFU's resident set is consuming more space than it has been allotted. In
2127 * this situation, we must victimize our own cache, the MFU, for this insertion.
2130 arc_get_data_buf(arc_buf_t
*buf
)
2132 arc_state_t
*state
= buf
->b_hdr
->b_state
;
2133 uint64_t size
= buf
->b_hdr
->b_size
;
2134 arc_buf_contents_t type
= buf
->b_hdr
->b_type
;
2136 arc_adapt(size
, state
);
2139 * We have not yet reached cache maximum size,
2140 * just allocate a new buffer.
2142 if (!arc_evict_needed(type
)) {
2143 if (type
== ARC_BUFC_METADATA
) {
2144 buf
->b_data
= zio_buf_alloc(size
);
2145 arc_space_consume(size
, ARC_SPACE_DATA
);
2147 ASSERT(type
== ARC_BUFC_DATA
);
2148 buf
->b_data
= zio_data_buf_alloc(size
);
2149 ARCSTAT_INCR(arcstat_data_size
, size
);
2150 atomic_add_64(&arc_size
, size
);
2156 * If we are prefetching from the mfu ghost list, this buffer
2157 * will end up on the mru list; so steal space from there.
2159 if (state
== arc_mfu_ghost
)
2160 state
= buf
->b_hdr
->b_flags
& ARC_PREFETCH
? arc_mru
: arc_mfu
;
2161 else if (state
== arc_mru_ghost
)
2164 if (state
== arc_mru
|| state
== arc_anon
) {
2165 uint64_t mru_used
= arc_anon
->arcs_size
+ arc_mru
->arcs_size
;
2166 state
= (arc_mfu
->arcs_lsize
[type
] >= size
&&
2167 arc_p
> mru_used
) ? arc_mfu
: arc_mru
;
2170 uint64_t mfu_space
= arc_c
- arc_p
;
2171 state
= (arc_mru
->arcs_lsize
[type
] >= size
&&
2172 mfu_space
> arc_mfu
->arcs_size
) ? arc_mru
: arc_mfu
;
2174 if ((buf
->b_data
= arc_evict(state
, NULL
, size
, TRUE
, type
)) == NULL
) {
2175 if (type
== ARC_BUFC_METADATA
) {
2176 buf
->b_data
= zio_buf_alloc(size
);
2177 arc_space_consume(size
, ARC_SPACE_DATA
);
2179 ASSERT(type
== ARC_BUFC_DATA
);
2180 buf
->b_data
= zio_data_buf_alloc(size
);
2181 ARCSTAT_INCR(arcstat_data_size
, size
);
2182 atomic_add_64(&arc_size
, size
);
2184 ARCSTAT_BUMP(arcstat_recycle_miss
);
2186 ASSERT(buf
->b_data
!= NULL
);
2189 * Update the state size. Note that ghost states have a
2190 * "ghost size" and so don't need to be updated.
2192 if (!GHOST_STATE(buf
->b_hdr
->b_state
)) {
2193 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
2195 atomic_add_64(&hdr
->b_state
->arcs_size
, size
);
2196 if (list_link_active(&hdr
->b_arc_node
)) {
2197 ASSERT(refcount_is_zero(&hdr
->b_refcnt
));
2198 atomic_add_64(&hdr
->b_state
->arcs_lsize
[type
], size
);
2201 * If we are growing the cache, and we are adding anonymous
2202 * data, and we have outgrown arc_p, update arc_p
2204 if (arc_size
< arc_c
&& hdr
->b_state
== arc_anon
&&
2205 arc_anon
->arcs_size
+ arc_mru
->arcs_size
> arc_p
)
2206 arc_p
= MIN(arc_c
, arc_p
+ size
);
2211 * This routine is called whenever a buffer is accessed.
2212 * NOTE: the hash lock is dropped in this function.
2215 arc_access(arc_buf_hdr_t
*buf
, kmutex_t
*hash_lock
)
2217 ASSERT(MUTEX_HELD(hash_lock
));
2219 if (buf
->b_state
== arc_anon
) {
2221 * This buffer is not in the cache, and does not
2222 * appear in our "ghost" list. Add the new buffer
2226 ASSERT(buf
->b_arc_access
== 0);
2227 buf
->b_arc_access
= lbolt
;
2228 DTRACE_PROBE1(new_state__mru
, arc_buf_hdr_t
*, buf
);
2229 arc_change_state(arc_mru
, buf
, hash_lock
);
2231 } else if (buf
->b_state
== arc_mru
) {
2233 * If this buffer is here because of a prefetch, then either:
2234 * - clear the flag if this is a "referencing" read
2235 * (any subsequent access will bump this into the MFU state).
2237 * - move the buffer to the head of the list if this is
2238 * another prefetch (to make it less likely to be evicted).
2240 if ((buf
->b_flags
& ARC_PREFETCH
) != 0) {
2241 if (refcount_count(&buf
->b_refcnt
) == 0) {
2242 ASSERT(list_link_active(&buf
->b_arc_node
));
2244 buf
->b_flags
&= ~ARC_PREFETCH
;
2245 ARCSTAT_BUMP(arcstat_mru_hits
);
2247 buf
->b_arc_access
= lbolt
;
2252 * This buffer has been "accessed" only once so far,
2253 * but it is still in the cache. Move it to the MFU
2256 if (lbolt
> buf
->b_arc_access
+ ARC_MINTIME
) {
2258 * More than 125ms have passed since we
2259 * instantiated this buffer. Move it to the
2260 * most frequently used state.
2262 buf
->b_arc_access
= lbolt
;
2263 DTRACE_PROBE1(new_state__mfu
, arc_buf_hdr_t
*, buf
);
2264 arc_change_state(arc_mfu
, buf
, hash_lock
);
2266 ARCSTAT_BUMP(arcstat_mru_hits
);
2267 } else if (buf
->b_state
== arc_mru_ghost
) {
2268 arc_state_t
*new_state
;
2270 * This buffer has been "accessed" recently, but
2271 * was evicted from the cache. Move it to the
2275 if (buf
->b_flags
& ARC_PREFETCH
) {
2276 new_state
= arc_mru
;
2277 if (refcount_count(&buf
->b_refcnt
) > 0)
2278 buf
->b_flags
&= ~ARC_PREFETCH
;
2279 DTRACE_PROBE1(new_state__mru
, arc_buf_hdr_t
*, buf
);
2281 new_state
= arc_mfu
;
2282 DTRACE_PROBE1(new_state__mfu
, arc_buf_hdr_t
*, buf
);
2285 buf
->b_arc_access
= lbolt
;
2286 arc_change_state(new_state
, buf
, hash_lock
);
2288 ARCSTAT_BUMP(arcstat_mru_ghost_hits
);
2289 } else if (buf
->b_state
== arc_mfu
) {
2291 * This buffer has been accessed more than once and is
2292 * still in the cache. Keep it in the MFU state.
2294 * NOTE: an add_reference() that occurred when we did
2295 * the arc_read() will have kicked this off the list.
2296 * If it was a prefetch, we will explicitly move it to
2297 * the head of the list now.
2299 if ((buf
->b_flags
& ARC_PREFETCH
) != 0) {
2300 ASSERT(refcount_count(&buf
->b_refcnt
) == 0);
2301 ASSERT(list_link_active(&buf
->b_arc_node
));
2303 ARCSTAT_BUMP(arcstat_mfu_hits
);
2304 buf
->b_arc_access
= lbolt
;
2305 } else if (buf
->b_state
== arc_mfu_ghost
) {
2306 arc_state_t
*new_state
= arc_mfu
;
2308 * This buffer has been accessed more than once but has
2309 * been evicted from the cache. Move it back to the
2313 if (buf
->b_flags
& ARC_PREFETCH
) {
2315 * This is a prefetch access...
2316 * move this block back to the MRU state.
2318 ASSERT3U(refcount_count(&buf
->b_refcnt
), ==, 0);
2319 new_state
= arc_mru
;
2322 buf
->b_arc_access
= lbolt
;
2323 DTRACE_PROBE1(new_state__mfu
, arc_buf_hdr_t
*, buf
);
2324 arc_change_state(new_state
, buf
, hash_lock
);
2326 ARCSTAT_BUMP(arcstat_mfu_ghost_hits
);
2327 } else if (buf
->b_state
== arc_l2c_only
) {
2329 * This buffer is on the 2nd Level ARC.
2332 buf
->b_arc_access
= lbolt
;
2333 DTRACE_PROBE1(new_state__mfu
, arc_buf_hdr_t
*, buf
);
2334 arc_change_state(arc_mfu
, buf
, hash_lock
);
2336 ASSERT(!"invalid arc state");
2340 /* a generic arc_done_func_t which you can use */
2343 arc_bcopy_func(zio_t
*zio
, arc_buf_t
*buf
, void *arg
)
2345 bcopy(buf
->b_data
, arg
, buf
->b_hdr
->b_size
);
2346 VERIFY(arc_buf_remove_ref(buf
, arg
) == 1);
2349 /* a generic arc_done_func_t */
2351 arc_getbuf_func(zio_t
*zio
, arc_buf_t
*buf
, void *arg
)
2353 arc_buf_t
**bufp
= arg
;
2354 if (zio
&& zio
->io_error
) {
2355 VERIFY(arc_buf_remove_ref(buf
, arg
) == 1);
2363 arc_read_done(zio_t
*zio
)
2365 arc_buf_hdr_t
*hdr
, *found
;
2367 arc_buf_t
*abuf
; /* buffer we're assigning to callback */
2368 kmutex_t
*hash_lock
;
2369 arc_callback_t
*callback_list
, *acb
;
2370 int freeable
= FALSE
;
2372 buf
= zio
->io_private
;
2376 * The hdr was inserted into hash-table and removed from lists
2377 * prior to starting I/O. We should find this header, since
2378 * it's in the hash table, and it should be legit since it's
2379 * not possible to evict it during the I/O. The only possible
2380 * reason for it not to be found is if we were freed during the
2383 found
= buf_hash_find(hdr
->b_spa
, &hdr
->b_dva
, hdr
->b_birth
,
2386 ASSERT((found
== NULL
&& HDR_FREED_IN_READ(hdr
) && hash_lock
== NULL
) ||
2387 (found
== hdr
&& DVA_EQUAL(&hdr
->b_dva
, BP_IDENTITY(zio
->io_bp
))) ||
2388 (found
== hdr
&& HDR_L2_READING(hdr
)));
2390 hdr
->b_flags
&= ~ARC_L2_EVICTED
;
2391 if (l2arc_noprefetch
&& (hdr
->b_flags
& ARC_PREFETCH
))
2392 hdr
->b_flags
&= ~ARC_L2CACHE
;
2394 /* byteswap if necessary */
2395 callback_list
= hdr
->b_acb
;
2396 ASSERT(callback_list
!= NULL
);
2397 if (BP_SHOULD_BYTESWAP(zio
->io_bp
)) {
2398 arc_byteswap_func_t
*func
= BP_GET_LEVEL(zio
->io_bp
) > 0 ?
2399 byteswap_uint64_array
:
2400 dmu_ot
[BP_GET_TYPE(zio
->io_bp
)].ot_byteswap
;
2401 func(buf
->b_data
, hdr
->b_size
);
2404 arc_cksum_compute(buf
, B_FALSE
);
2406 /* create copies of the data buffer for the callers */
2408 for (acb
= callback_list
; acb
; acb
= acb
->acb_next
) {
2409 if (acb
->acb_done
) {
2411 abuf
= arc_buf_clone(buf
);
2412 acb
->acb_buf
= abuf
;
2417 hdr
->b_flags
&= ~ARC_IO_IN_PROGRESS
;
2418 ASSERT(!HDR_BUF_AVAILABLE(hdr
));
2420 hdr
->b_flags
|= ARC_BUF_AVAILABLE
;
2422 ASSERT(refcount_is_zero(&hdr
->b_refcnt
) || callback_list
!= NULL
);
2424 if (zio
->io_error
!= 0) {
2425 hdr
->b_flags
|= ARC_IO_ERROR
;
2426 if (hdr
->b_state
!= arc_anon
)
2427 arc_change_state(arc_anon
, hdr
, hash_lock
);
2428 if (HDR_IN_HASH_TABLE(hdr
))
2429 buf_hash_remove(hdr
);
2430 freeable
= refcount_is_zero(&hdr
->b_refcnt
);
2434 * Broadcast before we drop the hash_lock to avoid the possibility
2435 * that the hdr (and hence the cv) might be freed before we get to
2436 * the cv_broadcast().
2438 cv_broadcast(&hdr
->b_cv
);
2442 * Only call arc_access on anonymous buffers. This is because
2443 * if we've issued an I/O for an evicted buffer, we've already
2444 * called arc_access (to prevent any simultaneous readers from
2445 * getting confused).
2447 if (zio
->io_error
== 0 && hdr
->b_state
== arc_anon
)
2448 arc_access(hdr
, hash_lock
);
2449 mutex_exit(hash_lock
);
2452 * This block was freed while we waited for the read to
2453 * complete. It has been removed from the hash table and
2454 * moved to the anonymous state (so that it won't show up
2457 ASSERT3P(hdr
->b_state
, ==, arc_anon
);
2458 freeable
= refcount_is_zero(&hdr
->b_refcnt
);
2461 /* execute each callback and free its structure */
2462 while ((acb
= callback_list
) != NULL
) {
2464 acb
->acb_done(zio
, acb
->acb_buf
, acb
->acb_private
);
2466 if (acb
->acb_zio_dummy
!= NULL
) {
2467 acb
->acb_zio_dummy
->io_error
= zio
->io_error
;
2468 zio_nowait(acb
->acb_zio_dummy
);
2471 callback_list
= acb
->acb_next
;
2472 kmem_free(acb
, sizeof (arc_callback_t
));
2476 arc_hdr_destroy(hdr
);
2480 * "Read" the block block at the specified DVA (in bp) via the
2481 * cache. If the block is found in the cache, invoke the provided
2482 * callback immediately and return. Note that the `zio' parameter
2483 * in the callback will be NULL in this case, since no IO was
2484 * required. If the block is not in the cache pass the read request
2485 * on to the spa with a substitute callback function, so that the
2486 * requested block will be added to the cache.
2488 * If a read request arrives for a block that has a read in-progress,
2489 * either wait for the in-progress read to complete (and return the
2490 * results); or, if this is a read with a "done" func, add a record
2491 * to the read to invoke the "done" func when the read completes,
2492 * and return; or just return.
2494 * arc_read_done() will invoke all the requested "done" functions
2495 * for readers of this block.
2497 * Normal callers should use arc_read and pass the arc buffer and offset
2498 * for the bp. But if you know you don't need locking, you can use
2502 arc_read(zio_t
*pio
, spa_t
*spa
, blkptr_t
*bp
, arc_buf_t
*pbuf
,
2503 arc_done_func_t
*done
, void *private, int priority
, int zio_flags
,
2504 uint32_t *arc_flags
, const zbookmark_t
*zb
)
2507 arc_buf_hdr_t
*hdr
= pbuf
->b_hdr
;
2509 ASSERT(!refcount_is_zero(&pbuf
->b_hdr
->b_refcnt
));
2510 ASSERT3U((char *)bp
- (char *)pbuf
->b_data
, <, pbuf
->b_hdr
->b_size
);
2511 rw_enter(&pbuf
->b_lock
, RW_READER
);
2513 err
= arc_read_nolock(pio
, spa
, bp
, done
, private, priority
,
2514 zio_flags
, arc_flags
, zb
);
2516 ASSERT3P(hdr
, ==, pbuf
->b_hdr
);
2517 rw_exit(&pbuf
->b_lock
);
2522 arc_read_nolock(zio_t
*pio
, spa_t
*spa
, blkptr_t
*bp
,
2523 arc_done_func_t
*done
, void *private, int priority
, int zio_flags
,
2524 uint32_t *arc_flags
, const zbookmark_t
*zb
)
2528 kmutex_t
*hash_lock
;
2530 uint64_t guid
= spa_guid(spa
);
2533 hdr
= buf_hash_find(guid
, BP_IDENTITY(bp
), bp
->blk_birth
, &hash_lock
);
2534 if (hdr
&& hdr
->b_datacnt
> 0) {
2536 *arc_flags
|= ARC_CACHED
;
2538 if (HDR_IO_IN_PROGRESS(hdr
)) {
2540 if (*arc_flags
& ARC_WAIT
) {
2541 cv_wait(&hdr
->b_cv
, hash_lock
);
2542 mutex_exit(hash_lock
);
2545 ASSERT(*arc_flags
& ARC_NOWAIT
);
2548 arc_callback_t
*acb
= NULL
;
2550 acb
= kmem_zalloc(sizeof (arc_callback_t
),
2552 acb
->acb_done
= done
;
2553 acb
->acb_private
= private;
2555 acb
->acb_zio_dummy
= zio_null(pio
,
2556 spa
, NULL
, NULL
, NULL
, zio_flags
);
2558 ASSERT(acb
->acb_done
!= NULL
);
2559 acb
->acb_next
= hdr
->b_acb
;
2561 add_reference(hdr
, hash_lock
, private);
2562 mutex_exit(hash_lock
);
2565 mutex_exit(hash_lock
);
2569 ASSERT(hdr
->b_state
== arc_mru
|| hdr
->b_state
== arc_mfu
);
2572 add_reference(hdr
, hash_lock
, private);
2574 * If this block is already in use, create a new
2575 * copy of the data so that we will be guaranteed
2576 * that arc_release() will always succeed.
2580 ASSERT(buf
->b_data
);
2581 if (HDR_BUF_AVAILABLE(hdr
)) {
2582 ASSERT(buf
->b_efunc
== NULL
);
2583 hdr
->b_flags
&= ~ARC_BUF_AVAILABLE
;
2585 buf
= arc_buf_clone(buf
);
2587 } else if (*arc_flags
& ARC_PREFETCH
&&
2588 refcount_count(&hdr
->b_refcnt
) == 0) {
2589 hdr
->b_flags
|= ARC_PREFETCH
;
2591 DTRACE_PROBE1(arc__hit
, arc_buf_hdr_t
*, hdr
);
2592 arc_access(hdr
, hash_lock
);
2593 if (*arc_flags
& ARC_L2CACHE
)
2594 hdr
->b_flags
|= ARC_L2CACHE
;
2595 mutex_exit(hash_lock
);
2596 ARCSTAT_BUMP(arcstat_hits
);
2597 ARCSTAT_CONDSTAT(!(hdr
->b_flags
& ARC_PREFETCH
),
2598 demand
, prefetch
, hdr
->b_type
!= ARC_BUFC_METADATA
,
2599 data
, metadata
, hits
);
2602 done(NULL
, buf
, private);
2604 uint64_t size
= BP_GET_LSIZE(bp
);
2605 arc_callback_t
*acb
;
2608 boolean_t devw
= B_FALSE
;
2611 /* this block is not in the cache */
2612 arc_buf_hdr_t
*exists
;
2613 arc_buf_contents_t type
= BP_GET_BUFC_TYPE(bp
);
2614 buf
= arc_buf_alloc(spa
, size
, private, type
);
2616 hdr
->b_dva
= *BP_IDENTITY(bp
);
2617 hdr
->b_birth
= bp
->blk_birth
;
2618 hdr
->b_cksum0
= bp
->blk_cksum
.zc_word
[0];
2619 exists
= buf_hash_insert(hdr
, &hash_lock
);
2621 /* somebody beat us to the hash insert */
2622 mutex_exit(hash_lock
);
2623 bzero(&hdr
->b_dva
, sizeof (dva_t
));
2626 (void) arc_buf_remove_ref(buf
, private);
2627 goto top
; /* restart the IO request */
2629 /* if this is a prefetch, we don't have a reference */
2630 if (*arc_flags
& ARC_PREFETCH
) {
2631 (void) remove_reference(hdr
, hash_lock
,
2633 hdr
->b_flags
|= ARC_PREFETCH
;
2635 if (*arc_flags
& ARC_L2CACHE
)
2636 hdr
->b_flags
|= ARC_L2CACHE
;
2637 if (BP_GET_LEVEL(bp
) > 0)
2638 hdr
->b_flags
|= ARC_INDIRECT
;
2640 /* this block is in the ghost cache */
2641 ASSERT(GHOST_STATE(hdr
->b_state
));
2642 ASSERT(!HDR_IO_IN_PROGRESS(hdr
));
2643 ASSERT3U(refcount_count(&hdr
->b_refcnt
), ==, 0);
2644 ASSERT(hdr
->b_buf
== NULL
);
2646 /* if this is a prefetch, we don't have a reference */
2647 if (*arc_flags
& ARC_PREFETCH
)
2648 hdr
->b_flags
|= ARC_PREFETCH
;
2650 add_reference(hdr
, hash_lock
, private);
2651 if (*arc_flags
& ARC_L2CACHE
)
2652 hdr
->b_flags
|= ARC_L2CACHE
;
2653 buf
= kmem_cache_alloc(buf_cache
, KM_PUSHPAGE
);
2656 buf
->b_efunc
= NULL
;
2657 buf
->b_private
= NULL
;
2660 arc_get_data_buf(buf
);
2661 ASSERT(hdr
->b_datacnt
== 0);
2666 acb
= kmem_zalloc(sizeof (arc_callback_t
), KM_SLEEP
);
2667 acb
->acb_done
= done
;
2668 acb
->acb_private
= private;
2670 ASSERT(hdr
->b_acb
== NULL
);
2672 hdr
->b_flags
|= ARC_IO_IN_PROGRESS
;
2675 * If the buffer has been evicted, migrate it to a present state
2676 * before issuing the I/O. Once we drop the hash-table lock,
2677 * the header will be marked as I/O in progress and have an
2678 * attached buffer. At this point, anybody who finds this
2679 * buffer ought to notice that it's legit but has a pending I/O.
2682 if (GHOST_STATE(hdr
->b_state
))
2683 arc_access(hdr
, hash_lock
);
2685 if (HDR_L2CACHE(hdr
) && hdr
->b_l2hdr
!= NULL
&&
2686 (vd
= hdr
->b_l2hdr
->b_dev
->l2ad_vdev
) != NULL
) {
2687 devw
= hdr
->b_l2hdr
->b_dev
->l2ad_writing
;
2688 addr
= hdr
->b_l2hdr
->b_daddr
;
2690 * Lock out device removal.
2692 if (vdev_is_dead(vd
) ||
2693 !spa_config_tryenter(spa
, SCL_L2ARC
, vd
, RW_READER
))
2697 mutex_exit(hash_lock
);
2699 ASSERT3U(hdr
->b_size
, ==, size
);
2700 DTRACE_PROBE3(arc__miss
, blkptr_t
*, bp
, uint64_t, size
,
2702 ARCSTAT_BUMP(arcstat_misses
);
2703 ARCSTAT_CONDSTAT(!(hdr
->b_flags
& ARC_PREFETCH
),
2704 demand
, prefetch
, hdr
->b_type
!= ARC_BUFC_METADATA
,
2705 data
, metadata
, misses
);
2707 if (vd
!= NULL
&& l2arc_ndev
!= 0 && !(l2arc_norw
&& devw
)) {
2709 * Read from the L2ARC if the following are true:
2710 * 1. The L2ARC vdev was previously cached.
2711 * 2. This buffer still has L2ARC metadata.
2712 * 3. This buffer isn't currently writing to the L2ARC.
2713 * 4. The L2ARC entry wasn't evicted, which may
2714 * also have invalidated the vdev.
2715 * 5. This isn't prefetch and l2arc_noprefetch is set.
2717 if (hdr
->b_l2hdr
!= NULL
&&
2718 !HDR_L2_WRITING(hdr
) && !HDR_L2_EVICTED(hdr
) &&
2719 !(l2arc_noprefetch
&& HDR_PREFETCH(hdr
))) {
2720 l2arc_read_callback_t
*cb
;
2722 DTRACE_PROBE1(l2arc__hit
, arc_buf_hdr_t
*, hdr
);
2723 ARCSTAT_BUMP(arcstat_l2_hits
);
2725 cb
= kmem_zalloc(sizeof (l2arc_read_callback_t
),
2727 cb
->l2rcb_buf
= buf
;
2728 cb
->l2rcb_spa
= spa
;
2731 cb
->l2rcb_flags
= zio_flags
;
2734 * l2arc read. The SCL_L2ARC lock will be
2735 * released by l2arc_read_done().
2737 rzio
= zio_read_phys(pio
, vd
, addr
, size
,
2738 buf
->b_data
, ZIO_CHECKSUM_OFF
,
2739 l2arc_read_done
, cb
, priority
, zio_flags
|
2740 ZIO_FLAG_DONT_CACHE
| ZIO_FLAG_CANFAIL
|
2741 ZIO_FLAG_DONT_PROPAGATE
|
2742 ZIO_FLAG_DONT_RETRY
, B_FALSE
);
2743 DTRACE_PROBE2(l2arc__read
, vdev_t
*, vd
,
2745 ARCSTAT_INCR(arcstat_l2_read_bytes
, size
);
2747 if (*arc_flags
& ARC_NOWAIT
) {
2752 ASSERT(*arc_flags
& ARC_WAIT
);
2753 if (zio_wait(rzio
) == 0)
2756 /* l2arc read error; goto zio_read() */
2758 DTRACE_PROBE1(l2arc__miss
,
2759 arc_buf_hdr_t
*, hdr
);
2760 ARCSTAT_BUMP(arcstat_l2_misses
);
2761 if (HDR_L2_WRITING(hdr
))
2762 ARCSTAT_BUMP(arcstat_l2_rw_clash
);
2763 spa_config_exit(spa
, SCL_L2ARC
, vd
);
2767 spa_config_exit(spa
, SCL_L2ARC
, vd
);
2768 if (l2arc_ndev
!= 0) {
2769 DTRACE_PROBE1(l2arc__miss
,
2770 arc_buf_hdr_t
*, hdr
);
2771 ARCSTAT_BUMP(arcstat_l2_misses
);
2775 rzio
= zio_read(pio
, spa
, bp
, buf
->b_data
, size
,
2776 arc_read_done
, buf
, priority
, zio_flags
, zb
);
2778 if (*arc_flags
& ARC_WAIT
)
2779 return (zio_wait(rzio
));
2781 ASSERT(*arc_flags
& ARC_NOWAIT
);
2788 * arc_read() variant to support pool traversal. If the block is already
2789 * in the ARC, make a copy of it; otherwise, the caller will do the I/O.
2790 * The idea is that we don't want pool traversal filling up memory, but
2791 * if the ARC already has the data anyway, we shouldn't pay for the I/O.
2794 arc_tryread(spa_t
*spa
, blkptr_t
*bp
, void *data
)
2798 uint64_t guid
= spa_guid(spa
);
2801 hdr
= buf_hash_find(guid
, BP_IDENTITY(bp
), bp
->blk_birth
, &hash_mtx
);
2803 if (hdr
&& hdr
->b_datacnt
> 0 && !HDR_IO_IN_PROGRESS(hdr
)) {
2804 arc_buf_t
*buf
= hdr
->b_buf
;
2807 while (buf
->b_data
== NULL
) {
2811 bcopy(buf
->b_data
, data
, hdr
->b_size
);
2817 mutex_exit(hash_mtx
);
2823 arc_set_callback(arc_buf_t
*buf
, arc_evict_func_t
*func
, void *private)
2825 ASSERT(buf
->b_hdr
!= NULL
);
2826 ASSERT(buf
->b_hdr
->b_state
!= arc_anon
);
2827 ASSERT(!refcount_is_zero(&buf
->b_hdr
->b_refcnt
) || func
== NULL
);
2828 buf
->b_efunc
= func
;
2829 buf
->b_private
= private;
2833 * This is used by the DMU to let the ARC know that a buffer is
2834 * being evicted, so the ARC should clean up. If this arc buf
2835 * is not yet in the evicted state, it will be put there.
2838 arc_buf_evict(arc_buf_t
*buf
)
2841 kmutex_t
*hash_lock
;
2844 rw_enter(&buf
->b_lock
, RW_WRITER
);
2848 * We are in arc_do_user_evicts().
2850 ASSERT(buf
->b_data
== NULL
);
2851 rw_exit(&buf
->b_lock
);
2853 } else if (buf
->b_data
== NULL
) {
2854 arc_buf_t copy
= *buf
; /* structure assignment */
2856 * We are on the eviction list; process this buffer now
2857 * but let arc_do_user_evicts() do the reaping.
2859 buf
->b_efunc
= NULL
;
2860 rw_exit(&buf
->b_lock
);
2861 VERIFY(copy
.b_efunc(©
) == 0);
2864 hash_lock
= HDR_LOCK(hdr
);
2865 mutex_enter(hash_lock
);
2867 ASSERT(buf
->b_hdr
== hdr
);
2868 ASSERT3U(refcount_count(&hdr
->b_refcnt
), <, hdr
->b_datacnt
);
2869 ASSERT(hdr
->b_state
== arc_mru
|| hdr
->b_state
== arc_mfu
);
2872 * Pull this buffer off of the hdr
2875 while (*bufp
!= buf
)
2876 bufp
= &(*bufp
)->b_next
;
2877 *bufp
= buf
->b_next
;
2879 ASSERT(buf
->b_data
!= NULL
);
2880 arc_buf_destroy(buf
, FALSE
, FALSE
);
2882 if (hdr
->b_datacnt
== 0) {
2883 arc_state_t
*old_state
= hdr
->b_state
;
2884 arc_state_t
*evicted_state
;
2886 ASSERT(refcount_is_zero(&hdr
->b_refcnt
));
2889 (old_state
== arc_mru
) ? arc_mru_ghost
: arc_mfu_ghost
;
2891 mutex_enter(&old_state
->arcs_mtx
);
2892 mutex_enter(&evicted_state
->arcs_mtx
);
2894 arc_change_state(evicted_state
, hdr
, hash_lock
);
2895 ASSERT(HDR_IN_HASH_TABLE(hdr
));
2896 hdr
->b_flags
|= ARC_IN_HASH_TABLE
;
2897 hdr
->b_flags
&= ~ARC_BUF_AVAILABLE
;
2899 mutex_exit(&evicted_state
->arcs_mtx
);
2900 mutex_exit(&old_state
->arcs_mtx
);
2902 mutex_exit(hash_lock
);
2903 rw_exit(&buf
->b_lock
);
2905 VERIFY(buf
->b_efunc(buf
) == 0);
2906 buf
->b_efunc
= NULL
;
2907 buf
->b_private
= NULL
;
2909 kmem_cache_free(buf_cache
, buf
);
2914 * Release this buffer from the cache. This must be done
2915 * after a read and prior to modifying the buffer contents.
2916 * If the buffer has more than one reference, we must make
2917 * a new hdr for the buffer.
2920 arc_release(arc_buf_t
*buf
, void *tag
)
2923 kmutex_t
*hash_lock
;
2924 l2arc_buf_hdr_t
*l2hdr
;
2927 rw_enter(&buf
->b_lock
, RW_WRITER
);
2930 /* this buffer is not on any list */
2931 ASSERT(refcount_count(&hdr
->b_refcnt
) > 0);
2932 ASSERT(!(hdr
->b_flags
& ARC_STORED
));
2934 if (hdr
->b_state
== arc_anon
) {
2935 /* this buffer is already released */
2936 ASSERT3U(refcount_count(&hdr
->b_refcnt
), ==, 1);
2937 ASSERT(BUF_EMPTY(hdr
));
2938 ASSERT(buf
->b_efunc
== NULL
);
2940 rw_exit(&buf
->b_lock
);
2944 hash_lock
= HDR_LOCK(hdr
);
2945 mutex_enter(hash_lock
);
2947 l2hdr
= hdr
->b_l2hdr
;
2949 mutex_enter(&l2arc_buflist_mtx
);
2950 hdr
->b_l2hdr
= NULL
;
2951 buf_size
= hdr
->b_size
;
2955 * Do we have more than one buf?
2957 if (hdr
->b_datacnt
> 1) {
2958 arc_buf_hdr_t
*nhdr
;
2960 uint64_t blksz
= hdr
->b_size
;
2961 uint64_t spa
= hdr
->b_spa
;
2962 arc_buf_contents_t type
= hdr
->b_type
;
2963 uint32_t flags
= hdr
->b_flags
;
2965 ASSERT(hdr
->b_buf
!= buf
|| buf
->b_next
!= NULL
);
2967 * Pull the data off of this buf and attach it to
2968 * a new anonymous buf.
2970 (void) remove_reference(hdr
, hash_lock
, tag
);
2972 while (*bufp
!= buf
)
2973 bufp
= &(*bufp
)->b_next
;
2974 *bufp
= (*bufp
)->b_next
;
2977 ASSERT3U(hdr
->b_state
->arcs_size
, >=, hdr
->b_size
);
2978 atomic_add_64(&hdr
->b_state
->arcs_size
, -hdr
->b_size
);
2979 if (refcount_is_zero(&hdr
->b_refcnt
)) {
2980 uint64_t *size
= &hdr
->b_state
->arcs_lsize
[hdr
->b_type
];
2981 ASSERT3U(*size
, >=, hdr
->b_size
);
2982 atomic_add_64(size
, -hdr
->b_size
);
2984 hdr
->b_datacnt
-= 1;
2985 arc_cksum_verify(buf
);
2987 mutex_exit(hash_lock
);
2989 nhdr
= kmem_cache_alloc(hdr_cache
, KM_PUSHPAGE
);
2990 nhdr
->b_size
= blksz
;
2992 nhdr
->b_type
= type
;
2994 nhdr
->b_state
= arc_anon
;
2995 nhdr
->b_arc_access
= 0;
2996 nhdr
->b_flags
= flags
& ARC_L2_WRITING
;
2997 nhdr
->b_l2hdr
= NULL
;
2998 nhdr
->b_datacnt
= 1;
2999 nhdr
->b_freeze_cksum
= NULL
;
3000 (void) refcount_add(&nhdr
->b_refcnt
, tag
);
3002 rw_exit(&buf
->b_lock
);
3003 atomic_add_64(&arc_anon
->arcs_size
, blksz
);
3005 rw_exit(&buf
->b_lock
);
3006 ASSERT(refcount_count(&hdr
->b_refcnt
) == 1);
3007 ASSERT(!list_link_active(&hdr
->b_arc_node
));
3008 ASSERT(!HDR_IO_IN_PROGRESS(hdr
));
3009 arc_change_state(arc_anon
, hdr
, hash_lock
);
3010 hdr
->b_arc_access
= 0;
3011 mutex_exit(hash_lock
);
3013 bzero(&hdr
->b_dva
, sizeof (dva_t
));
3018 buf
->b_efunc
= NULL
;
3019 buf
->b_private
= NULL
;
3022 list_remove(l2hdr
->b_dev
->l2ad_buflist
, hdr
);
3023 kmem_free(l2hdr
, sizeof (l2arc_buf_hdr_t
));
3024 ARCSTAT_INCR(arcstat_l2_size
, -buf_size
);
3025 mutex_exit(&l2arc_buflist_mtx
);
3030 arc_released(arc_buf_t
*buf
)
3034 rw_enter(&buf
->b_lock
, RW_READER
);
3035 released
= (buf
->b_data
!= NULL
&& buf
->b_hdr
->b_state
== arc_anon
);
3036 rw_exit(&buf
->b_lock
);
3041 arc_has_callback(arc_buf_t
*buf
)
3045 rw_enter(&buf
->b_lock
, RW_READER
);
3046 callback
= (buf
->b_efunc
!= NULL
);
3047 rw_exit(&buf
->b_lock
);
3053 arc_referenced(arc_buf_t
*buf
)
3057 rw_enter(&buf
->b_lock
, RW_READER
);
3058 referenced
= (refcount_count(&buf
->b_hdr
->b_refcnt
));
3059 rw_exit(&buf
->b_lock
);
3060 return (referenced
);
3065 arc_write_ready(zio_t
*zio
)
3067 arc_write_callback_t
*callback
= zio
->io_private
;
3068 arc_buf_t
*buf
= callback
->awcb_buf
;
3069 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
3071 ASSERT(!refcount_is_zero(&buf
->b_hdr
->b_refcnt
));
3072 callback
->awcb_ready(zio
, buf
, callback
->awcb_private
);
3075 * If the IO is already in progress, then this is a re-write
3076 * attempt, so we need to thaw and re-compute the cksum.
3077 * It is the responsibility of the callback to handle the
3078 * accounting for any re-write attempt.
3080 if (HDR_IO_IN_PROGRESS(hdr
)) {
3081 mutex_enter(&hdr
->b_freeze_lock
);
3082 if (hdr
->b_freeze_cksum
!= NULL
) {
3083 kmem_free(hdr
->b_freeze_cksum
, sizeof (zio_cksum_t
));
3084 hdr
->b_freeze_cksum
= NULL
;
3086 mutex_exit(&hdr
->b_freeze_lock
);
3088 arc_cksum_compute(buf
, B_FALSE
);
3089 hdr
->b_flags
|= ARC_IO_IN_PROGRESS
;
3093 arc_write_done(zio_t
*zio
)
3095 arc_write_callback_t
*callback
= zio
->io_private
;
3096 arc_buf_t
*buf
= callback
->awcb_buf
;
3097 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
3101 hdr
->b_dva
= *BP_IDENTITY(zio
->io_bp
);
3102 hdr
->b_birth
= zio
->io_bp
->blk_birth
;
3103 hdr
->b_cksum0
= zio
->io_bp
->blk_cksum
.zc_word
[0];
3105 * If the block to be written was all-zero, we may have
3106 * compressed it away. In this case no write was performed
3107 * so there will be no dva/birth-date/checksum. The buffer
3108 * must therefor remain anonymous (and uncached).
3110 if (!BUF_EMPTY(hdr
)) {
3111 arc_buf_hdr_t
*exists
;
3112 kmutex_t
*hash_lock
;
3114 arc_cksum_verify(buf
);
3116 exists
= buf_hash_insert(hdr
, &hash_lock
);
3119 * This can only happen if we overwrite for
3120 * sync-to-convergence, because we remove
3121 * buffers from the hash table when we arc_free().
3123 ASSERT(zio
->io_flags
& ZIO_FLAG_IO_REWRITE
);
3124 ASSERT(DVA_EQUAL(BP_IDENTITY(&zio
->io_bp_orig
),
3125 BP_IDENTITY(zio
->io_bp
)));
3126 ASSERT3U(zio
->io_bp_orig
.blk_birth
, ==,
3127 zio
->io_bp
->blk_birth
);
3129 ASSERT(refcount_is_zero(&exists
->b_refcnt
));
3130 arc_change_state(arc_anon
, exists
, hash_lock
);
3131 mutex_exit(hash_lock
);
3132 arc_hdr_destroy(exists
);
3133 exists
= buf_hash_insert(hdr
, &hash_lock
);
3134 ASSERT3P(exists
, ==, NULL
);
3136 hdr
->b_flags
&= ~ARC_IO_IN_PROGRESS
;
3137 /* if it's not anon, we are doing a scrub */
3138 if (hdr
->b_state
== arc_anon
)
3139 arc_access(hdr
, hash_lock
);
3140 mutex_exit(hash_lock
);
3141 } else if (callback
->awcb_done
== NULL
) {
3144 * This is an anonymous buffer with no user callback,
3145 * destroy it if there are no active references.
3147 mutex_enter(&arc_eviction_mtx
);
3148 destroy_hdr
= refcount_is_zero(&hdr
->b_refcnt
);
3149 hdr
->b_flags
&= ~ARC_IO_IN_PROGRESS
;
3150 mutex_exit(&arc_eviction_mtx
);
3152 arc_hdr_destroy(hdr
);
3154 hdr
->b_flags
&= ~ARC_IO_IN_PROGRESS
;
3156 hdr
->b_flags
&= ~ARC_STORED
;
3158 if (callback
->awcb_done
) {
3159 ASSERT(!refcount_is_zero(&hdr
->b_refcnt
));
3160 callback
->awcb_done(zio
, buf
, callback
->awcb_private
);
3163 kmem_free(callback
, sizeof (arc_write_callback_t
));
3167 write_policy(spa_t
*spa
, const writeprops_t
*wp
, zio_prop_t
*zp
)
3169 boolean_t ismd
= (wp
->wp_level
> 0 || dmu_ot
[wp
->wp_type
].ot_metadata
);
3171 /* Determine checksum setting */
3174 * Metadata always gets checksummed. If the data
3175 * checksum is multi-bit correctable, and it's not a
3176 * ZBT-style checksum, then it's suitable for metadata
3177 * as well. Otherwise, the metadata checksum defaults
3180 if (zio_checksum_table
[wp
->wp_oschecksum
].ci_correctable
&&
3181 !zio_checksum_table
[wp
->wp_oschecksum
].ci_zbt
)
3182 zp
->zp_checksum
= wp
->wp_oschecksum
;
3184 zp
->zp_checksum
= ZIO_CHECKSUM_FLETCHER_4
;
3186 zp
->zp_checksum
= zio_checksum_select(wp
->wp_dnchecksum
,
3190 /* Determine compression setting */
3193 * XXX -- we should design a compression algorithm
3194 * that specializes in arrays of bps.
3196 zp
->zp_compress
= zfs_mdcomp_disable
? ZIO_COMPRESS_EMPTY
:
3199 zp
->zp_compress
= zio_compress_select(wp
->wp_dncompress
,
3203 zp
->zp_type
= wp
->wp_type
;
3204 zp
->zp_level
= wp
->wp_level
;
3205 zp
->zp_ndvas
= MIN(wp
->wp_copies
+ ismd
, spa_max_replication(spa
));
3209 arc_write(zio_t
*pio
, spa_t
*spa
, const writeprops_t
*wp
,
3210 boolean_t l2arc
, uint64_t txg
, blkptr_t
*bp
, arc_buf_t
*buf
,
3211 arc_done_func_t
*ready
, arc_done_func_t
*done
, void *private, int priority
,
3212 int zio_flags
, const zbookmark_t
*zb
)
3214 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
3215 arc_write_callback_t
*callback
;
3219 ASSERT(ready
!= NULL
);
3220 ASSERT(!HDR_IO_ERROR(hdr
));
3221 ASSERT((hdr
->b_flags
& ARC_IO_IN_PROGRESS
) == 0);
3222 ASSERT(hdr
->b_acb
== 0);
3224 hdr
->b_flags
|= ARC_L2CACHE
;
3225 callback
= kmem_zalloc(sizeof (arc_write_callback_t
), KM_SLEEP
);
3226 callback
->awcb_ready
= ready
;
3227 callback
->awcb_done
= done
;
3228 callback
->awcb_private
= private;
3229 callback
->awcb_buf
= buf
;
3231 write_policy(spa
, wp
, &zp
);
3232 zio
= zio_write(pio
, spa
, txg
, bp
, buf
->b_data
, hdr
->b_size
, &zp
,
3233 arc_write_ready
, arc_write_done
, callback
, priority
, zio_flags
, zb
);
3239 arc_free(zio_t
*pio
, spa_t
*spa
, uint64_t txg
, blkptr_t
*bp
,
3240 zio_done_func_t
*done
, void *private, uint32_t arc_flags
)
3243 kmutex_t
*hash_lock
;
3245 uint64_t guid
= spa_guid(spa
);
3248 * If this buffer is in the cache, release it, so it
3251 ab
= buf_hash_find(guid
, BP_IDENTITY(bp
), bp
->blk_birth
, &hash_lock
);
3254 * The checksum of blocks to free is not always
3255 * preserved (eg. on the deadlist). However, if it is
3256 * nonzero, it should match what we have in the cache.
3258 ASSERT(bp
->blk_cksum
.zc_word
[0] == 0 ||
3259 bp
->blk_cksum
.zc_word
[0] == ab
->b_cksum0
||
3260 bp
->blk_fill
== BLK_FILL_ALREADY_FREED
);
3262 if (ab
->b_state
!= arc_anon
)
3263 arc_change_state(arc_anon
, ab
, hash_lock
);
3264 if (HDR_IO_IN_PROGRESS(ab
)) {
3266 * This should only happen when we prefetch.
3268 ASSERT(ab
->b_flags
& ARC_PREFETCH
);
3269 ASSERT3U(ab
->b_datacnt
, ==, 1);
3270 ab
->b_flags
|= ARC_FREED_IN_READ
;
3271 if (HDR_IN_HASH_TABLE(ab
))
3272 buf_hash_remove(ab
);
3273 ab
->b_arc_access
= 0;
3274 bzero(&ab
->b_dva
, sizeof (dva_t
));
3277 ab
->b_buf
->b_efunc
= NULL
;
3278 ab
->b_buf
->b_private
= NULL
;
3279 mutex_exit(hash_lock
);
3280 } else if (refcount_is_zero(&ab
->b_refcnt
)) {
3281 ab
->b_flags
|= ARC_FREE_IN_PROGRESS
;
3282 mutex_exit(hash_lock
);
3283 arc_hdr_destroy(ab
);
3284 ARCSTAT_BUMP(arcstat_deleted
);
3287 * We still have an active reference on this
3288 * buffer. This can happen, e.g., from
3289 * dbuf_unoverride().
3291 ASSERT(!HDR_IN_HASH_TABLE(ab
));
3292 ab
->b_arc_access
= 0;
3293 bzero(&ab
->b_dva
, sizeof (dva_t
));
3296 ab
->b_buf
->b_efunc
= NULL
;
3297 ab
->b_buf
->b_private
= NULL
;
3298 mutex_exit(hash_lock
);
3302 zio
= zio_free(pio
, spa
, txg
, bp
, done
, private, ZIO_FLAG_MUSTSUCCEED
);
3304 if (arc_flags
& ARC_WAIT
)
3305 return (zio_wait(zio
));
3307 ASSERT(arc_flags
& ARC_NOWAIT
);
3314 arc_memory_throttle(uint64_t reserve
, uint64_t txg
)
3317 uint64_t inflight_data
= arc_anon
->arcs_size
;
3318 uint64_t available_memory
= ptob(freemem
);
3319 static uint64_t page_load
= 0;
3320 static uint64_t last_txg
= 0;
3324 MIN(available_memory
, vmem_size(heap_arena
, VMEM_FREE
));
3326 if (available_memory
>= zfs_write_limit_max
)
3329 if (txg
> last_txg
) {
3334 * If we are in pageout, we know that memory is already tight,
3335 * the arc is already going to be evicting, so we just want to
3336 * continue to let page writes occur as quickly as possible.
3338 if (curproc
== proc_pageout
) {
3339 if (page_load
> MAX(ptob(minfree
), available_memory
) / 4)
3341 /* Note: reserve is inflated, so we deflate */
3342 page_load
+= reserve
/ 8;
3344 } else if (page_load
> 0 && arc_reclaim_needed()) {
3345 /* memory is low, delay before restarting */
3346 ARCSTAT_INCR(arcstat_memory_throttle_count
, 1);
3351 if (arc_size
> arc_c_min
) {
3352 uint64_t evictable_memory
=
3353 arc_mru
->arcs_lsize
[ARC_BUFC_DATA
] +
3354 arc_mru
->arcs_lsize
[ARC_BUFC_METADATA
] +
3355 arc_mfu
->arcs_lsize
[ARC_BUFC_DATA
] +
3356 arc_mfu
->arcs_lsize
[ARC_BUFC_METADATA
];
3357 available_memory
+= MIN(evictable_memory
, arc_size
- arc_c_min
);
3360 if (inflight_data
> available_memory
/ 4) {
3361 ARCSTAT_INCR(arcstat_memory_throttle_count
, 1);
3369 arc_tempreserve_clear(uint64_t reserve
)
3371 atomic_add_64(&arc_tempreserve
, -reserve
);
3372 ASSERT((int64_t)arc_tempreserve
>= 0);
3376 arc_tempreserve_space(uint64_t reserve
, uint64_t txg
)
3382 * Once in a while, fail for no reason. Everything should cope.
3384 if (spa_get_random(10000) == 0) {
3385 dprintf("forcing random failure\n");
3389 if (reserve
> arc_c
/4 && !arc_no_grow
)
3390 arc_c
= MIN(arc_c_max
, reserve
* 4);
3391 if (reserve
> arc_c
)
3395 * Writes will, almost always, require additional memory allocations
3396 * in order to compress/encrypt/etc the data. We therefor need to
3397 * make sure that there is sufficient available memory for this.
3399 if (error
= arc_memory_throttle(reserve
, txg
))
3403 * Throttle writes when the amount of dirty data in the cache
3404 * gets too large. We try to keep the cache less than half full
3405 * of dirty blocks so that our sync times don't grow too large.
3406 * Note: if two requests come in concurrently, we might let them
3407 * both succeed, when one of them should fail. Not a huge deal.
3409 if (reserve
+ arc_tempreserve
+ arc_anon
->arcs_size
> arc_c
/ 2 &&
3410 arc_anon
->arcs_size
> arc_c
/ 4) {
3411 dprintf("failing, arc_tempreserve=%lluK anon_meta=%lluK "
3412 "anon_data=%lluK tempreserve=%lluK arc_c=%lluK\n",
3413 arc_tempreserve
>>10,
3414 arc_anon
->arcs_lsize
[ARC_BUFC_METADATA
]>>10,
3415 arc_anon
->arcs_lsize
[ARC_BUFC_DATA
]>>10,
3416 reserve
>>10, arc_c
>>10);
3419 atomic_add_64(&arc_tempreserve
, reserve
);
3426 mutex_init(&arc_reclaim_thr_lock
, NULL
, MUTEX_DEFAULT
, NULL
);
3427 cv_init(&arc_reclaim_thr_cv
, NULL
, CV_DEFAULT
, NULL
);
3429 /* Convert seconds to clock ticks */
3430 arc_min_prefetch_lifespan
= 1 * hz
;
3432 /* Start out with 1/8 of all memory */
3433 arc_c
= physmem
* PAGESIZE
/ 8;
3437 * On architectures where the physical memory can be larger
3438 * than the addressable space (intel in 32-bit mode), we may
3439 * need to limit the cache to 1/8 of VM size.
3441 arc_c
= MIN(arc_c
, vmem_size(heap_arena
, VMEM_ALLOC
| VMEM_FREE
) / 8);
3444 /* set min cache to 1/32 of all memory, or 64MB, whichever is more */
3445 arc_c_min
= MAX(arc_c
/ 4, 64<<20);
3446 /* set max to 3/4 of all memory, or all but 1GB, whichever is more */
3447 if (arc_c
* 8 >= 1<<30)
3448 arc_c_max
= (arc_c
* 8) - (1<<30);
3450 arc_c_max
= arc_c_min
;
3451 arc_c_max
= MAX(arc_c
* 6, arc_c_max
);
3454 * Allow the tunables to override our calculations if they are
3455 * reasonable (ie. over 64MB)
3457 if (zfs_arc_max
> 64<<20 && zfs_arc_max
< physmem
* PAGESIZE
)
3458 arc_c_max
= zfs_arc_max
;
3459 if (zfs_arc_min
> 64<<20 && zfs_arc_min
<= arc_c_max
)
3460 arc_c_min
= zfs_arc_min
;
3463 arc_p
= (arc_c
>> 1);
3465 /* limit meta-data to 1/4 of the arc capacity */
3466 arc_meta_limit
= arc_c_max
/ 4;
3468 /* Allow the tunable to override if it is reasonable */
3469 if (zfs_arc_meta_limit
> 0 && zfs_arc_meta_limit
<= arc_c_max
)
3470 arc_meta_limit
= zfs_arc_meta_limit
;
3472 if (arc_c_min
< arc_meta_limit
/ 2 && zfs_arc_min
== 0)
3473 arc_c_min
= arc_meta_limit
/ 2;
3475 if (zfs_arc_grow_retry
> 0)
3476 arc_grow_retry
= zfs_arc_grow_retry
;
3478 if (zfs_arc_shrink_shift
> 0)
3479 arc_shrink_shift
= zfs_arc_shrink_shift
;
3481 if (zfs_arc_p_min_shift
> 0)
3482 arc_p_min_shift
= zfs_arc_p_min_shift
;
3484 /* if kmem_flags are set, lets try to use less memory */
3485 if (kmem_debugging())
3487 if (arc_c
< arc_c_min
)
3490 arc_anon
= &ARC_anon
;
3492 arc_mru_ghost
= &ARC_mru_ghost
;
3494 arc_mfu_ghost
= &ARC_mfu_ghost
;
3495 arc_l2c_only
= &ARC_l2c_only
;
3498 mutex_init(&arc_anon
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3499 mutex_init(&arc_mru
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3500 mutex_init(&arc_mru_ghost
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3501 mutex_init(&arc_mfu
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3502 mutex_init(&arc_mfu_ghost
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3503 mutex_init(&arc_l2c_only
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3505 list_create(&arc_mru
->arcs_list
[ARC_BUFC_METADATA
],
3506 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3507 list_create(&arc_mru
->arcs_list
[ARC_BUFC_DATA
],
3508 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3509 list_create(&arc_mru_ghost
->arcs_list
[ARC_BUFC_METADATA
],
3510 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3511 list_create(&arc_mru_ghost
->arcs_list
[ARC_BUFC_DATA
],
3512 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3513 list_create(&arc_mfu
->arcs_list
[ARC_BUFC_METADATA
],
3514 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3515 list_create(&arc_mfu
->arcs_list
[ARC_BUFC_DATA
],
3516 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3517 list_create(&arc_mfu_ghost
->arcs_list
[ARC_BUFC_METADATA
],
3518 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3519 list_create(&arc_mfu_ghost
->arcs_list
[ARC_BUFC_DATA
],
3520 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3521 list_create(&arc_l2c_only
->arcs_list
[ARC_BUFC_METADATA
],
3522 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3523 list_create(&arc_l2c_only
->arcs_list
[ARC_BUFC_DATA
],
3524 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3528 arc_thread_exit
= 0;
3529 arc_eviction_list
= NULL
;
3530 mutex_init(&arc_eviction_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3531 bzero(&arc_eviction_hdr
, sizeof (arc_buf_hdr_t
));
3533 arc_ksp
= kstat_create("zfs", 0, "arcstats", "misc", KSTAT_TYPE_NAMED
,
3534 sizeof (arc_stats
) / sizeof (kstat_named_t
), KSTAT_FLAG_VIRTUAL
);
3536 if (arc_ksp
!= NULL
) {
3537 arc_ksp
->ks_data
= &arc_stats
;
3538 kstat_install(arc_ksp
);
3541 (void) thread_create(NULL
, 0, arc_reclaim_thread
, NULL
, 0, &p0
,
3542 TS_RUN
, minclsyspri
);
3547 if (zfs_write_limit_max
== 0)
3548 zfs_write_limit_max
= ptob(physmem
) >> zfs_write_limit_shift
;
3550 zfs_write_limit_shift
= 0;
3551 mutex_init(&zfs_write_limit_lock
, NULL
, MUTEX_DEFAULT
, NULL
);
3557 mutex_enter(&arc_reclaim_thr_lock
);
3558 arc_thread_exit
= 1;
3559 while (arc_thread_exit
!= 0)
3560 cv_wait(&arc_reclaim_thr_cv
, &arc_reclaim_thr_lock
);
3561 mutex_exit(&arc_reclaim_thr_lock
);
3567 if (arc_ksp
!= NULL
) {
3568 kstat_delete(arc_ksp
);
3572 mutex_destroy(&arc_eviction_mtx
);
3573 mutex_destroy(&arc_reclaim_thr_lock
);
3574 cv_destroy(&arc_reclaim_thr_cv
);
3576 list_destroy(&arc_mru
->arcs_list
[ARC_BUFC_METADATA
]);
3577 list_destroy(&arc_mru_ghost
->arcs_list
[ARC_BUFC_METADATA
]);
3578 list_destroy(&arc_mfu
->arcs_list
[ARC_BUFC_METADATA
]);
3579 list_destroy(&arc_mfu_ghost
->arcs_list
[ARC_BUFC_METADATA
]);
3580 list_destroy(&arc_mru
->arcs_list
[ARC_BUFC_DATA
]);
3581 list_destroy(&arc_mru_ghost
->arcs_list
[ARC_BUFC_DATA
]);
3582 list_destroy(&arc_mfu
->arcs_list
[ARC_BUFC_DATA
]);
3583 list_destroy(&arc_mfu_ghost
->arcs_list
[ARC_BUFC_DATA
]);
3585 mutex_destroy(&arc_anon
->arcs_mtx
);
3586 mutex_destroy(&arc_mru
->arcs_mtx
);
3587 mutex_destroy(&arc_mru_ghost
->arcs_mtx
);
3588 mutex_destroy(&arc_mfu
->arcs_mtx
);
3589 mutex_destroy(&arc_mfu_ghost
->arcs_mtx
);
3590 mutex_destroy(&arc_l2c_only
->arcs_mtx
);
3592 mutex_destroy(&zfs_write_limit_lock
);
3600 * The level 2 ARC (L2ARC) is a cache layer in-between main memory and disk.
3601 * It uses dedicated storage devices to hold cached data, which are populated
3602 * using large infrequent writes. The main role of this cache is to boost
3603 * the performance of random read workloads. The intended L2ARC devices
3604 * include short-stroked disks, solid state disks, and other media with
3605 * substantially faster read latency than disk.
3607 * +-----------------------+
3609 * +-----------------------+
3612 * l2arc_feed_thread() arc_read()
3616 * +---------------+ |
3618 * +---------------+ |
3623 * +-------+ +-------+
3625 * | cache | | cache |
3626 * +-------+ +-------+
3627 * +=========+ .-----.
3628 * : L2ARC : |-_____-|
3629 * : devices : | Disks |
3630 * +=========+ `-_____-'
3632 * Read requests are satisfied from the following sources, in order:
3635 * 2) vdev cache of L2ARC devices
3637 * 4) vdev cache of disks
3640 * Some L2ARC device types exhibit extremely slow write performance.
3641 * To accommodate for this there are some significant differences between
3642 * the L2ARC and traditional cache design:
3644 * 1. There is no eviction path from the ARC to the L2ARC. Evictions from
3645 * the ARC behave as usual, freeing buffers and placing headers on ghost
3646 * lists. The ARC does not send buffers to the L2ARC during eviction as
3647 * this would add inflated write latencies for all ARC memory pressure.
3649 * 2. The L2ARC attempts to cache data from the ARC before it is evicted.
3650 * It does this by periodically scanning buffers from the eviction-end of
3651 * the MFU and MRU ARC lists, copying them to the L2ARC devices if they are
3652 * not already there. It scans until a headroom of buffers is satisfied,
3653 * which itself is a buffer for ARC eviction. The thread that does this is
3654 * l2arc_feed_thread(), illustrated below; example sizes are included to
3655 * provide a better sense of ratio than this diagram:
3658 * +---------------------+----------+
3659 * ARC_mfu |:::::#:::::::::::::::|o#o###o###|-->. # already on L2ARC
3660 * +---------------------+----------+ | o L2ARC eligible
3661 * ARC_mru |:#:::::::::::::::::::|#o#ooo####|-->| : ARC buffer
3662 * +---------------------+----------+ |
3663 * 15.9 Gbytes ^ 32 Mbytes |
3665 * l2arc_feed_thread()
3667 * l2arc write hand <--[oooo]--'
3671 * +==============================+
3672 * L2ARC dev |####|#|###|###| |####| ... |
3673 * +==============================+
3676 * 3. If an ARC buffer is copied to the L2ARC but then hit instead of
3677 * evicted, then the L2ARC has cached a buffer much sooner than it probably
3678 * needed to, potentially wasting L2ARC device bandwidth and storage. It is
3679 * safe to say that this is an uncommon case, since buffers at the end of
3680 * the ARC lists have moved there due to inactivity.
3682 * 4. If the ARC evicts faster than the L2ARC can maintain a headroom,
3683 * then the L2ARC simply misses copying some buffers. This serves as a
3684 * pressure valve to prevent heavy read workloads from both stalling the ARC
3685 * with waits and clogging the L2ARC with writes. This also helps prevent
3686 * the potential for the L2ARC to churn if it attempts to cache content too
3687 * quickly, such as during backups of the entire pool.
3689 * 5. After system boot and before the ARC has filled main memory, there are
3690 * no evictions from the ARC and so the tails of the ARC_mfu and ARC_mru
3691 * lists can remain mostly static. Instead of searching from tail of these
3692 * lists as pictured, the l2arc_feed_thread() will search from the list heads
3693 * for eligible buffers, greatly increasing its chance of finding them.
3695 * The L2ARC device write speed is also boosted during this time so that
3696 * the L2ARC warms up faster. Since there have been no ARC evictions yet,
3697 * there are no L2ARC reads, and no fear of degrading read performance
3698 * through increased writes.
3700 * 6. Writes to the L2ARC devices are grouped and sent in-sequence, so that
3701 * the vdev queue can aggregate them into larger and fewer writes. Each
3702 * device is written to in a rotor fashion, sweeping writes through
3703 * available space then repeating.
3705 * 7. The L2ARC does not store dirty content. It never needs to flush
3706 * write buffers back to disk based storage.
3708 * 8. If an ARC buffer is written (and dirtied) which also exists in the
3709 * L2ARC, the now stale L2ARC buffer is immediately dropped.
3711 * The performance of the L2ARC can be tweaked by a number of tunables, which
3712 * may be necessary for different workloads:
3714 * l2arc_write_max max write bytes per interval
3715 * l2arc_write_boost extra write bytes during device warmup
3716 * l2arc_noprefetch skip caching prefetched buffers
3717 * l2arc_headroom number of max device writes to precache
3718 * l2arc_feed_secs seconds between L2ARC writing
3720 * Tunables may be removed or added as future performance improvements are
3721 * integrated, and also may become zpool properties.
3723 * There are three key functions that control how the L2ARC warms up:
3725 * l2arc_write_eligible() check if a buffer is eligible to cache
3726 * l2arc_write_size() calculate how much to write
3727 * l2arc_write_interval() calculate sleep delay between writes
3729 * These three functions determine what to write, how much, and how quickly
3734 l2arc_write_eligible(uint64_t spa_guid
, arc_buf_hdr_t
*ab
)
3737 * A buffer is *not* eligible for the L2ARC if it:
3738 * 1. belongs to a different spa.
3739 * 2. has no attached buffer.
3740 * 3. is already cached on the L2ARC.
3741 * 4. has an I/O in progress (it may be an incomplete read).
3742 * 5. is flagged not eligible (zfs property).
3744 if (ab
->b_spa
!= spa_guid
|| ab
->b_buf
== NULL
|| ab
->b_l2hdr
!= NULL
||
3745 HDR_IO_IN_PROGRESS(ab
) || !HDR_L2CACHE(ab
))
3752 l2arc_write_size(l2arc_dev_t
*dev
)
3756 size
= dev
->l2ad_write
;
3758 if (arc_warm
== B_FALSE
)
3759 size
+= dev
->l2ad_boost
;
3766 l2arc_write_interval(clock_t began
, uint64_t wanted
, uint64_t wrote
)
3768 clock_t interval
, next
;
3771 * If the ARC lists are busy, increase our write rate; if the
3772 * lists are stale, idle back. This is achieved by checking
3773 * how much we previously wrote - if it was more than half of
3774 * what we wanted, schedule the next write much sooner.
3776 if (l2arc_feed_again
&& wrote
> (wanted
/ 2))
3777 interval
= (hz
* l2arc_feed_min_ms
) / 1000;
3779 interval
= hz
* l2arc_feed_secs
;
3781 next
= MAX(lbolt
, MIN(lbolt
+ interval
, began
+ interval
));
3787 l2arc_hdr_stat_add(void)
3789 ARCSTAT_INCR(arcstat_l2_hdr_size
, HDR_SIZE
+ L2HDR_SIZE
);
3790 ARCSTAT_INCR(arcstat_hdr_size
, -HDR_SIZE
);
3794 l2arc_hdr_stat_remove(void)
3796 ARCSTAT_INCR(arcstat_l2_hdr_size
, -(HDR_SIZE
+ L2HDR_SIZE
));
3797 ARCSTAT_INCR(arcstat_hdr_size
, HDR_SIZE
);
3801 * Cycle through L2ARC devices. This is how L2ARC load balances.
3802 * If a device is returned, this also returns holding the spa config lock.
3804 static l2arc_dev_t
*
3805 l2arc_dev_get_next(void)
3807 l2arc_dev_t
*first
, *next
= NULL
;
3810 * Lock out the removal of spas (spa_namespace_lock), then removal
3811 * of cache devices (l2arc_dev_mtx). Once a device has been selected,
3812 * both locks will be dropped and a spa config lock held instead.
3814 mutex_enter(&spa_namespace_lock
);
3815 mutex_enter(&l2arc_dev_mtx
);
3817 /* if there are no vdevs, there is nothing to do */
3818 if (l2arc_ndev
== 0)
3822 next
= l2arc_dev_last
;
3824 /* loop around the list looking for a non-faulted vdev */
3826 next
= list_head(l2arc_dev_list
);
3828 next
= list_next(l2arc_dev_list
, next
);
3830 next
= list_head(l2arc_dev_list
);
3833 /* if we have come back to the start, bail out */
3836 else if (next
== first
)
3839 } while (vdev_is_dead(next
->l2ad_vdev
));
3841 /* if we were unable to find any usable vdevs, return NULL */
3842 if (vdev_is_dead(next
->l2ad_vdev
))
3845 l2arc_dev_last
= next
;
3848 mutex_exit(&l2arc_dev_mtx
);
3851 * Grab the config lock to prevent the 'next' device from being
3852 * removed while we are writing to it.
3855 spa_config_enter(next
->l2ad_spa
, SCL_L2ARC
, next
, RW_READER
);
3856 mutex_exit(&spa_namespace_lock
);
3862 * Free buffers that were tagged for destruction.
3865 l2arc_do_free_on_write()
3868 l2arc_data_free_t
*df
, *df_prev
;
3870 mutex_enter(&l2arc_free_on_write_mtx
);
3871 buflist
= l2arc_free_on_write
;
3873 for (df
= list_tail(buflist
); df
; df
= df_prev
) {
3874 df_prev
= list_prev(buflist
, df
);
3875 ASSERT(df
->l2df_data
!= NULL
);
3876 ASSERT(df
->l2df_func
!= NULL
);
3877 df
->l2df_func(df
->l2df_data
, df
->l2df_size
);
3878 list_remove(buflist
, df
);
3879 kmem_free(df
, sizeof (l2arc_data_free_t
));
3882 mutex_exit(&l2arc_free_on_write_mtx
);
3886 * A write to a cache device has completed. Update all headers to allow
3887 * reads from these buffers to begin.
3890 l2arc_write_done(zio_t
*zio
)
3892 l2arc_write_callback_t
*cb
;
3895 arc_buf_hdr_t
*head
, *ab
, *ab_prev
;
3896 l2arc_buf_hdr_t
*abl2
;
3897 kmutex_t
*hash_lock
;
3899 cb
= zio
->io_private
;
3901 dev
= cb
->l2wcb_dev
;
3902 ASSERT(dev
!= NULL
);
3903 head
= cb
->l2wcb_head
;
3904 ASSERT(head
!= NULL
);
3905 buflist
= dev
->l2ad_buflist
;
3906 ASSERT(buflist
!= NULL
);
3907 DTRACE_PROBE2(l2arc__iodone
, zio_t
*, zio
,
3908 l2arc_write_callback_t
*, cb
);
3910 if (zio
->io_error
!= 0)
3911 ARCSTAT_BUMP(arcstat_l2_writes_error
);
3913 mutex_enter(&l2arc_buflist_mtx
);
3916 * All writes completed, or an error was hit.
3918 for (ab
= list_prev(buflist
, head
); ab
; ab
= ab_prev
) {
3919 ab_prev
= list_prev(buflist
, ab
);
3921 hash_lock
= HDR_LOCK(ab
);
3922 if (!mutex_tryenter(hash_lock
)) {
3924 * This buffer misses out. It may be in a stage
3925 * of eviction. Its ARC_L2_WRITING flag will be
3926 * left set, denying reads to this buffer.
3928 ARCSTAT_BUMP(arcstat_l2_writes_hdr_miss
);
3932 if (zio
->io_error
!= 0) {
3934 * Error - drop L2ARC entry.
3936 list_remove(buflist
, ab
);
3939 kmem_free(abl2
, sizeof (l2arc_buf_hdr_t
));
3940 ARCSTAT_INCR(arcstat_l2_size
, -ab
->b_size
);
3944 * Allow ARC to begin reads to this L2ARC entry.
3946 ab
->b_flags
&= ~ARC_L2_WRITING
;
3948 mutex_exit(hash_lock
);
3951 atomic_inc_64(&l2arc_writes_done
);
3952 list_remove(buflist
, head
);
3953 kmem_cache_free(hdr_cache
, head
);
3954 mutex_exit(&l2arc_buflist_mtx
);
3956 l2arc_do_free_on_write();
3958 kmem_free(cb
, sizeof (l2arc_write_callback_t
));
3962 * A read to a cache device completed. Validate buffer contents before
3963 * handing over to the regular ARC routines.
3966 l2arc_read_done(zio_t
*zio
)
3968 l2arc_read_callback_t
*cb
;
3971 kmutex_t
*hash_lock
;
3974 ASSERT(zio
->io_vd
!= NULL
);
3975 ASSERT(zio
->io_flags
& ZIO_FLAG_DONT_PROPAGATE
);
3977 spa_config_exit(zio
->io_spa
, SCL_L2ARC
, zio
->io_vd
);
3979 cb
= zio
->io_private
;
3981 buf
= cb
->l2rcb_buf
;
3982 ASSERT(buf
!= NULL
);
3984 ASSERT(hdr
!= NULL
);
3986 hash_lock
= HDR_LOCK(hdr
);
3987 mutex_enter(hash_lock
);
3990 * Check this survived the L2ARC journey.
3992 equal
= arc_cksum_equal(buf
);
3993 if (equal
&& zio
->io_error
== 0 && !HDR_L2_EVICTED(hdr
)) {
3994 mutex_exit(hash_lock
);
3995 zio
->io_private
= buf
;
3996 zio
->io_bp_copy
= cb
->l2rcb_bp
; /* XXX fix in L2ARC 2.0 */
3997 zio
->io_bp
= &zio
->io_bp_copy
; /* XXX fix in L2ARC 2.0 */
4000 mutex_exit(hash_lock
);
4002 * Buffer didn't survive caching. Increment stats and
4003 * reissue to the original storage device.
4005 if (zio
->io_error
!= 0) {
4006 ARCSTAT_BUMP(arcstat_l2_io_error
);
4008 zio
->io_error
= EIO
;
4011 ARCSTAT_BUMP(arcstat_l2_cksum_bad
);
4014 * If there's no waiter, issue an async i/o to the primary
4015 * storage now. If there *is* a waiter, the caller must
4016 * issue the i/o in a context where it's OK to block.
4018 if (zio
->io_waiter
== NULL
) {
4019 zio_t
*pio
= zio_unique_parent(zio
);
4021 ASSERT(!pio
|| pio
->io_child_type
== ZIO_CHILD_LOGICAL
);
4023 zio_nowait(zio_read(pio
, cb
->l2rcb_spa
, &cb
->l2rcb_bp
,
4024 buf
->b_data
, zio
->io_size
, arc_read_done
, buf
,
4025 zio
->io_priority
, cb
->l2rcb_flags
, &cb
->l2rcb_zb
));
4029 kmem_free(cb
, sizeof (l2arc_read_callback_t
));
4033 * This is the list priority from which the L2ARC will search for pages to
4034 * cache. This is used within loops (0..3) to cycle through lists in the
4035 * desired order. This order can have a significant effect on cache
4038 * Currently the metadata lists are hit first, MFU then MRU, followed by
4039 * the data lists. This function returns a locked list, and also returns
4043 l2arc_list_locked(int list_num
, kmutex_t
**lock
)
4047 ASSERT(list_num
>= 0 && list_num
<= 3);
4051 list
= &arc_mfu
->arcs_list
[ARC_BUFC_METADATA
];
4052 *lock
= &arc_mfu
->arcs_mtx
;
4055 list
= &arc_mru
->arcs_list
[ARC_BUFC_METADATA
];
4056 *lock
= &arc_mru
->arcs_mtx
;
4059 list
= &arc_mfu
->arcs_list
[ARC_BUFC_DATA
];
4060 *lock
= &arc_mfu
->arcs_mtx
;
4063 list
= &arc_mru
->arcs_list
[ARC_BUFC_DATA
];
4064 *lock
= &arc_mru
->arcs_mtx
;
4068 ASSERT(!(MUTEX_HELD(*lock
)));
4074 * Evict buffers from the device write hand to the distance specified in
4075 * bytes. This distance may span populated buffers, it may span nothing.
4076 * This is clearing a region on the L2ARC device ready for writing.
4077 * If the 'all' boolean is set, every buffer is evicted.
4080 l2arc_evict(l2arc_dev_t
*dev
, uint64_t distance
, boolean_t all
)
4083 l2arc_buf_hdr_t
*abl2
;
4084 arc_buf_hdr_t
*ab
, *ab_prev
;
4085 kmutex_t
*hash_lock
;
4088 buflist
= dev
->l2ad_buflist
;
4090 if (buflist
== NULL
)
4093 if (!all
&& dev
->l2ad_first
) {
4095 * This is the first sweep through the device. There is
4101 if (dev
->l2ad_hand
>= (dev
->l2ad_end
- (2 * distance
))) {
4103 * When nearing the end of the device, evict to the end
4104 * before the device write hand jumps to the start.
4106 taddr
= dev
->l2ad_end
;
4108 taddr
= dev
->l2ad_hand
+ distance
;
4110 DTRACE_PROBE4(l2arc__evict
, l2arc_dev_t
*, dev
, list_t
*, buflist
,
4111 uint64_t, taddr
, boolean_t
, all
);
4114 mutex_enter(&l2arc_buflist_mtx
);
4115 for (ab
= list_tail(buflist
); ab
; ab
= ab_prev
) {
4116 ab_prev
= list_prev(buflist
, ab
);
4118 hash_lock
= HDR_LOCK(ab
);
4119 if (!mutex_tryenter(hash_lock
)) {
4121 * Missed the hash lock. Retry.
4123 ARCSTAT_BUMP(arcstat_l2_evict_lock_retry
);
4124 mutex_exit(&l2arc_buflist_mtx
);
4125 mutex_enter(hash_lock
);
4126 mutex_exit(hash_lock
);
4130 if (HDR_L2_WRITE_HEAD(ab
)) {
4132 * We hit a write head node. Leave it for
4133 * l2arc_write_done().
4135 list_remove(buflist
, ab
);
4136 mutex_exit(hash_lock
);
4140 if (!all
&& ab
->b_l2hdr
!= NULL
&&
4141 (ab
->b_l2hdr
->b_daddr
> taddr
||
4142 ab
->b_l2hdr
->b_daddr
< dev
->l2ad_hand
)) {
4144 * We've evicted to the target address,
4145 * or the end of the device.
4147 mutex_exit(hash_lock
);
4151 if (HDR_FREE_IN_PROGRESS(ab
)) {
4153 * Already on the path to destruction.
4155 mutex_exit(hash_lock
);
4159 if (ab
->b_state
== arc_l2c_only
) {
4160 ASSERT(!HDR_L2_READING(ab
));
4162 * This doesn't exist in the ARC. Destroy.
4163 * arc_hdr_destroy() will call list_remove()
4164 * and decrement arcstat_l2_size.
4166 arc_change_state(arc_anon
, ab
, hash_lock
);
4167 arc_hdr_destroy(ab
);
4170 * Invalidate issued or about to be issued
4171 * reads, since we may be about to write
4172 * over this location.
4174 if (HDR_L2_READING(ab
)) {
4175 ARCSTAT_BUMP(arcstat_l2_evict_reading
);
4176 ab
->b_flags
|= ARC_L2_EVICTED
;
4180 * Tell ARC this no longer exists in L2ARC.
4182 if (ab
->b_l2hdr
!= NULL
) {
4185 kmem_free(abl2
, sizeof (l2arc_buf_hdr_t
));
4186 ARCSTAT_INCR(arcstat_l2_size
, -ab
->b_size
);
4188 list_remove(buflist
, ab
);
4191 * This may have been leftover after a
4194 ab
->b_flags
&= ~ARC_L2_WRITING
;
4196 mutex_exit(hash_lock
);
4198 mutex_exit(&l2arc_buflist_mtx
);
4200 spa_l2cache_space_update(dev
->l2ad_vdev
, 0, -(taddr
- dev
->l2ad_evict
));
4201 dev
->l2ad_evict
= taddr
;
4205 * Find and write ARC buffers to the L2ARC device.
4207 * An ARC_L2_WRITING flag is set so that the L2ARC buffers are not valid
4208 * for reading until they have completed writing.
4211 l2arc_write_buffers(spa_t
*spa
, l2arc_dev_t
*dev
, uint64_t target_sz
)
4213 arc_buf_hdr_t
*ab
, *ab_prev
, *head
;
4214 l2arc_buf_hdr_t
*hdrl2
;
4216 uint64_t passed_sz
, write_sz
, buf_sz
, headroom
;
4218 kmutex_t
*hash_lock
, *list_lock
;
4219 boolean_t have_lock
, full
;
4220 l2arc_write_callback_t
*cb
;
4222 uint64_t guid
= spa_guid(spa
);
4224 ASSERT(dev
->l2ad_vdev
!= NULL
);
4229 head
= kmem_cache_alloc(hdr_cache
, KM_PUSHPAGE
);
4230 head
->b_flags
|= ARC_L2_WRITE_HEAD
;
4233 * Copy buffers for L2ARC writing.
4235 mutex_enter(&l2arc_buflist_mtx
);
4236 for (int try = 0; try <= 3; try++) {
4237 list
= l2arc_list_locked(try, &list_lock
);
4241 * L2ARC fast warmup.
4243 * Until the ARC is warm and starts to evict, read from the
4244 * head of the ARC lists rather than the tail.
4246 headroom
= target_sz
* l2arc_headroom
;
4247 if (arc_warm
== B_FALSE
)
4248 ab
= list_head(list
);
4250 ab
= list_tail(list
);
4252 for (; ab
; ab
= ab_prev
) {
4253 if (arc_warm
== B_FALSE
)
4254 ab_prev
= list_next(list
, ab
);
4256 ab_prev
= list_prev(list
, ab
);
4258 hash_lock
= HDR_LOCK(ab
);
4259 have_lock
= MUTEX_HELD(hash_lock
);
4260 if (!have_lock
&& !mutex_tryenter(hash_lock
)) {
4262 * Skip this buffer rather than waiting.
4267 passed_sz
+= ab
->b_size
;
4268 if (passed_sz
> headroom
) {
4272 mutex_exit(hash_lock
);
4276 if (!l2arc_write_eligible(guid
, ab
)) {
4277 mutex_exit(hash_lock
);
4281 if ((write_sz
+ ab
->b_size
) > target_sz
) {
4283 mutex_exit(hash_lock
);
4289 * Insert a dummy header on the buflist so
4290 * l2arc_write_done() can find where the
4291 * write buffers begin without searching.
4293 list_insert_head(dev
->l2ad_buflist
, head
);
4296 sizeof (l2arc_write_callback_t
), KM_SLEEP
);
4297 cb
->l2wcb_dev
= dev
;
4298 cb
->l2wcb_head
= head
;
4299 pio
= zio_root(spa
, l2arc_write_done
, cb
,
4304 * Create and add a new L2ARC header.
4306 hdrl2
= kmem_zalloc(sizeof (l2arc_buf_hdr_t
), KM_SLEEP
);
4308 hdrl2
->b_daddr
= dev
->l2ad_hand
;
4310 ab
->b_flags
|= ARC_L2_WRITING
;
4311 ab
->b_l2hdr
= hdrl2
;
4312 list_insert_head(dev
->l2ad_buflist
, ab
);
4313 buf_data
= ab
->b_buf
->b_data
;
4314 buf_sz
= ab
->b_size
;
4317 * Compute and store the buffer cksum before
4318 * writing. On debug the cksum is verified first.
4320 arc_cksum_verify(ab
->b_buf
);
4321 arc_cksum_compute(ab
->b_buf
, B_TRUE
);
4323 mutex_exit(hash_lock
);
4325 wzio
= zio_write_phys(pio
, dev
->l2ad_vdev
,
4326 dev
->l2ad_hand
, buf_sz
, buf_data
, ZIO_CHECKSUM_OFF
,
4327 NULL
, NULL
, ZIO_PRIORITY_ASYNC_WRITE
,
4328 ZIO_FLAG_CANFAIL
, B_FALSE
);
4330 DTRACE_PROBE2(l2arc__write
, vdev_t
*, dev
->l2ad_vdev
,
4332 (void) zio_nowait(wzio
);
4335 * Keep the clock hand suitably device-aligned.
4337 buf_sz
= vdev_psize_to_asize(dev
->l2ad_vdev
, buf_sz
);
4340 dev
->l2ad_hand
+= buf_sz
;
4343 mutex_exit(list_lock
);
4348 mutex_exit(&l2arc_buflist_mtx
);
4351 ASSERT3U(write_sz
, ==, 0);
4352 kmem_cache_free(hdr_cache
, head
);
4356 ASSERT3U(write_sz
, <=, target_sz
);
4357 ARCSTAT_BUMP(arcstat_l2_writes_sent
);
4358 ARCSTAT_INCR(arcstat_l2_write_bytes
, write_sz
);
4359 ARCSTAT_INCR(arcstat_l2_size
, write_sz
);
4360 spa_l2cache_space_update(dev
->l2ad_vdev
, 0, write_sz
);
4363 * Bump device hand to the device start if it is approaching the end.
4364 * l2arc_evict() will already have evicted ahead for this case.
4366 if (dev
->l2ad_hand
>= (dev
->l2ad_end
- target_sz
)) {
4367 spa_l2cache_space_update(dev
->l2ad_vdev
, 0,
4368 dev
->l2ad_end
- dev
->l2ad_hand
);
4369 dev
->l2ad_hand
= dev
->l2ad_start
;
4370 dev
->l2ad_evict
= dev
->l2ad_start
;
4371 dev
->l2ad_first
= B_FALSE
;
4374 dev
->l2ad_writing
= B_TRUE
;
4375 (void) zio_wait(pio
);
4376 dev
->l2ad_writing
= B_FALSE
;
4382 * This thread feeds the L2ARC at regular intervals. This is the beating
4383 * heart of the L2ARC.
4386 l2arc_feed_thread(void)
4391 uint64_t size
, wrote
;
4392 clock_t begin
, next
= lbolt
;
4394 CALLB_CPR_INIT(&cpr
, &l2arc_feed_thr_lock
, callb_generic_cpr
, FTAG
);
4396 mutex_enter(&l2arc_feed_thr_lock
);
4398 while (l2arc_thread_exit
== 0) {
4399 CALLB_CPR_SAFE_BEGIN(&cpr
);
4400 (void) cv_timedwait(&l2arc_feed_thr_cv
, &l2arc_feed_thr_lock
,
4402 CALLB_CPR_SAFE_END(&cpr
, &l2arc_feed_thr_lock
);
4406 * Quick check for L2ARC devices.
4408 mutex_enter(&l2arc_dev_mtx
);
4409 if (l2arc_ndev
== 0) {
4410 mutex_exit(&l2arc_dev_mtx
);
4413 mutex_exit(&l2arc_dev_mtx
);
4417 * This selects the next l2arc device to write to, and in
4418 * doing so the next spa to feed from: dev->l2ad_spa. This
4419 * will return NULL if there are now no l2arc devices or if
4420 * they are all faulted.
4422 * If a device is returned, its spa's config lock is also
4423 * held to prevent device removal. l2arc_dev_get_next()
4424 * will grab and release l2arc_dev_mtx.
4426 if ((dev
= l2arc_dev_get_next()) == NULL
)
4429 spa
= dev
->l2ad_spa
;
4430 ASSERT(spa
!= NULL
);
4433 * Avoid contributing to memory pressure.
4435 if (arc_reclaim_needed()) {
4436 ARCSTAT_BUMP(arcstat_l2_abort_lowmem
);
4437 spa_config_exit(spa
, SCL_L2ARC
, dev
);
4441 ARCSTAT_BUMP(arcstat_l2_feeds
);
4443 size
= l2arc_write_size(dev
);
4446 * Evict L2ARC buffers that will be overwritten.
4448 l2arc_evict(dev
, size
, B_FALSE
);
4451 * Write ARC buffers.
4453 wrote
= l2arc_write_buffers(spa
, dev
, size
);
4456 * Calculate interval between writes.
4458 next
= l2arc_write_interval(begin
, size
, wrote
);
4459 spa_config_exit(spa
, SCL_L2ARC
, dev
);
4462 l2arc_thread_exit
= 0;
4463 cv_broadcast(&l2arc_feed_thr_cv
);
4464 CALLB_CPR_EXIT(&cpr
); /* drops l2arc_feed_thr_lock */
4469 l2arc_vdev_present(vdev_t
*vd
)
4473 mutex_enter(&l2arc_dev_mtx
);
4474 for (dev
= list_head(l2arc_dev_list
); dev
!= NULL
;
4475 dev
= list_next(l2arc_dev_list
, dev
)) {
4476 if (dev
->l2ad_vdev
== vd
)
4479 mutex_exit(&l2arc_dev_mtx
);
4481 return (dev
!= NULL
);
4485 * Add a vdev for use by the L2ARC. By this point the spa has already
4486 * validated the vdev and opened it.
4489 l2arc_add_vdev(spa_t
*spa
, vdev_t
*vd
, uint64_t start
, uint64_t end
)
4491 l2arc_dev_t
*adddev
;
4493 ASSERT(!l2arc_vdev_present(vd
));
4496 * Create a new l2arc device entry.
4498 adddev
= kmem_zalloc(sizeof (l2arc_dev_t
), KM_SLEEP
);
4499 adddev
->l2ad_spa
= spa
;
4500 adddev
->l2ad_vdev
= vd
;
4501 adddev
->l2ad_write
= l2arc_write_max
;
4502 adddev
->l2ad_boost
= l2arc_write_boost
;
4503 adddev
->l2ad_start
= start
;
4504 adddev
->l2ad_end
= end
;
4505 adddev
->l2ad_hand
= adddev
->l2ad_start
;
4506 adddev
->l2ad_evict
= adddev
->l2ad_start
;
4507 adddev
->l2ad_first
= B_TRUE
;
4508 adddev
->l2ad_writing
= B_FALSE
;
4509 ASSERT3U(adddev
->l2ad_write
, >, 0);
4512 * This is a list of all ARC buffers that are still valid on the
4515 adddev
->l2ad_buflist
= kmem_zalloc(sizeof (list_t
), KM_SLEEP
);
4516 list_create(adddev
->l2ad_buflist
, sizeof (arc_buf_hdr_t
),
4517 offsetof(arc_buf_hdr_t
, b_l2node
));
4519 spa_l2cache_space_update(vd
, adddev
->l2ad_end
- adddev
->l2ad_hand
, 0);
4522 * Add device to global list
4524 mutex_enter(&l2arc_dev_mtx
);
4525 list_insert_head(l2arc_dev_list
, adddev
);
4526 atomic_inc_64(&l2arc_ndev
);
4527 mutex_exit(&l2arc_dev_mtx
);
4531 * Remove a vdev from the L2ARC.
4534 l2arc_remove_vdev(vdev_t
*vd
)
4536 l2arc_dev_t
*dev
, *nextdev
, *remdev
= NULL
;
4539 * Find the device by vdev
4541 mutex_enter(&l2arc_dev_mtx
);
4542 for (dev
= list_head(l2arc_dev_list
); dev
; dev
= nextdev
) {
4543 nextdev
= list_next(l2arc_dev_list
, dev
);
4544 if (vd
== dev
->l2ad_vdev
) {
4549 ASSERT(remdev
!= NULL
);
4552 * Remove device from global list
4554 list_remove(l2arc_dev_list
, remdev
);
4555 l2arc_dev_last
= NULL
; /* may have been invalidated */
4556 atomic_dec_64(&l2arc_ndev
);
4557 mutex_exit(&l2arc_dev_mtx
);
4560 * Clear all buflists and ARC references. L2ARC device flush.
4562 l2arc_evict(remdev
, 0, B_TRUE
);
4563 list_destroy(remdev
->l2ad_buflist
);
4564 kmem_free(remdev
->l2ad_buflist
, sizeof (list_t
));
4565 kmem_free(remdev
, sizeof (l2arc_dev_t
));
4571 l2arc_thread_exit
= 0;
4573 l2arc_writes_sent
= 0;
4574 l2arc_writes_done
= 0;
4576 mutex_init(&l2arc_feed_thr_lock
, NULL
, MUTEX_DEFAULT
, NULL
);
4577 cv_init(&l2arc_feed_thr_cv
, NULL
, CV_DEFAULT
, NULL
);
4578 mutex_init(&l2arc_dev_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
4579 mutex_init(&l2arc_buflist_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
4580 mutex_init(&l2arc_free_on_write_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
4582 l2arc_dev_list
= &L2ARC_dev_list
;
4583 l2arc_free_on_write
= &L2ARC_free_on_write
;
4584 list_create(l2arc_dev_list
, sizeof (l2arc_dev_t
),
4585 offsetof(l2arc_dev_t
, l2ad_node
));
4586 list_create(l2arc_free_on_write
, sizeof (l2arc_data_free_t
),
4587 offsetof(l2arc_data_free_t
, l2df_list_node
));
4594 * This is called from dmu_fini(), which is called from spa_fini();
4595 * Because of this, we can assume that all l2arc devices have
4596 * already been removed when the pools themselves were removed.
4599 l2arc_do_free_on_write();
4601 mutex_destroy(&l2arc_feed_thr_lock
);
4602 cv_destroy(&l2arc_feed_thr_cv
);
4603 mutex_destroy(&l2arc_dev_mtx
);
4604 mutex_destroy(&l2arc_buflist_mtx
);
4605 mutex_destroy(&l2arc_free_on_write_mtx
);
4607 list_destroy(l2arc_dev_list
);
4608 list_destroy(l2arc_free_on_write
);
4614 if (!(spa_mode_global
& FWRITE
))
4617 (void) thread_create(NULL
, 0, l2arc_feed_thread
, NULL
, 0, &p0
,
4618 TS_RUN
, minclsyspri
);
4624 if (!(spa_mode_global
& FWRITE
))
4627 mutex_enter(&l2arc_feed_thr_lock
);
4628 cv_signal(&l2arc_feed_thr_cv
); /* kick thread out of startup */
4629 l2arc_thread_exit
= 1;
4630 while (l2arc_thread_exit
!= 0)
4631 cv_wait(&l2arc_feed_thr_cv
, &l2arc_feed_thr_lock
);
4632 mutex_exit(&l2arc_feed_thr_lock
);