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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
26 * DVA-based Adjustable Replacement Cache
28 * While much of the theory of operation used here is
29 * based on the self-tuning, low overhead replacement cache
30 * presented by Megiddo and Modha at FAST 2003, there are some
31 * significant differences:
33 * 1. The Megiddo and Modha model assumes any page is evictable.
34 * Pages in its cache cannot be "locked" into memory. This makes
35 * the eviction algorithm simple: evict the last page in the list.
36 * This also make the performance characteristics easy to reason
37 * about. Our cache is not so simple. At any given moment, some
38 * subset of the blocks in the cache are un-evictable because we
39 * have handed out a reference to them. Blocks are only evictable
40 * when there are no external references active. This makes
41 * eviction far more problematic: we choose to evict the evictable
42 * blocks that are the "lowest" in the list.
44 * There are times when it is not possible to evict the requested
45 * space. In these circumstances we are unable to adjust the cache
46 * size. To prevent the cache growing unbounded at these times we
47 * implement a "cache throttle" that slows the flow of new data
48 * into the cache until we can make space available.
50 * 2. The Megiddo and Modha model assumes a fixed cache size.
51 * Pages are evicted when the cache is full and there is a cache
52 * miss. Our model has a variable sized cache. It grows with
53 * high use, but also tries to react to memory pressure from the
54 * operating system: decreasing its size when system memory is
57 * 3. The Megiddo and Modha model assumes a fixed page size. All
58 * elements of the cache are therefor exactly the same size. So
59 * when adjusting the cache size following a cache miss, its simply
60 * a matter of choosing a single page to evict. In our model, we
61 * have variable sized cache blocks (rangeing from 512 bytes to
62 * 128K bytes). We therefor choose a set of blocks to evict to make
63 * space for a cache miss that approximates as closely as possible
64 * the space used by the new block.
66 * See also: "ARC: A Self-Tuning, Low Overhead Replacement Cache"
67 * by N. Megiddo & D. Modha, FAST 2003
73 * A new reference to a cache buffer can be obtained in two
74 * ways: 1) via a hash table lookup using the DVA as a key,
75 * or 2) via one of the ARC lists. The arc_read() interface
76 * uses method 1, while the internal arc algorithms for
77 * adjusting the cache use method 2. We therefor provide two
78 * types of locks: 1) the hash table lock array, and 2) the
81 * Buffers do not have their own mutexs, rather they rely on the
82 * hash table mutexs for the bulk of their protection (i.e. most
83 * fields in the arc_buf_hdr_t are protected by these mutexs).
85 * buf_hash_find() returns the appropriate mutex (held) when it
86 * locates the requested buffer in the hash table. It returns
87 * NULL for the mutex if the buffer was not in the table.
89 * buf_hash_remove() expects the appropriate hash mutex to be
90 * already held before it is invoked.
92 * Each arc state also has a mutex which is used to protect the
93 * buffer list associated with the state. When attempting to
94 * obtain a hash table lock while holding an arc list lock you
95 * must use: mutex_tryenter() to avoid deadlock. Also note that
96 * the active state mutex must be held before the ghost state mutex.
98 * Arc buffers may have an associated eviction callback function.
99 * This function will be invoked prior to removing the buffer (e.g.
100 * in arc_do_user_evicts()). Note however that the data associated
101 * with the buffer may be evicted prior to the callback. The callback
102 * must be made with *no locks held* (to prevent deadlock). Additionally,
103 * the users of callbacks must ensure that their private data is
104 * protected from simultaneous callbacks from arc_buf_evict()
105 * and arc_do_user_evicts().
107 * Note that the majority of the performance stats are manipulated
108 * with atomic operations.
110 * The L2ARC uses the l2arc_buflist_mtx global mutex for the following:
112 * - L2ARC buflist creation
113 * - L2ARC buflist eviction
114 * - L2ARC write completion, which walks L2ARC buflists
115 * - ARC header destruction, as it removes from L2ARC buflists
116 * - ARC header release, as it removes from L2ARC buflists
121 #include <sys/zfs_context.h>
123 #include <sys/refcount.h>
124 #include <sys/vdev.h>
125 #include <sys/vdev_impl.h>
127 #include <sys/vmsystm.h>
129 #include <sys/fs/swapnode.h>
130 #include <sys/dnlc.h>
132 #include <sys/callb.h>
133 #include <sys/kstat.h>
134 #include <zfs_fletcher.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_arc_grow_retry
= 0;
181 int zfs_arc_shrink_shift
= 0;
182 int zfs_arc_p_min_shift
= 0;
185 * Note that buffers can be in one of 6 states:
186 * ARC_anon - anonymous (discussed below)
187 * ARC_mru - recently used, currently cached
188 * ARC_mru_ghost - recentely used, no longer in cache
189 * ARC_mfu - frequently used, currently cached
190 * ARC_mfu_ghost - frequently used, no longer in cache
191 * ARC_l2c_only - exists in L2ARC but not other states
192 * When there are no active references to the buffer, they are
193 * are linked onto a list in one of these arc states. These are
194 * the only buffers that can be evicted or deleted. Within each
195 * state there are multiple lists, one for meta-data and one for
196 * non-meta-data. Meta-data (indirect blocks, blocks of dnodes,
197 * etc.) is tracked separately so that it can be managed more
198 * explicitly: favored over data, limited explicitly.
200 * Anonymous buffers are buffers that are not associated with
201 * a DVA. These are buffers that hold dirty block copies
202 * before they are written to stable storage. By definition,
203 * they are "ref'd" and are considered part of arc_mru
204 * that cannot be freed. Generally, they will aquire a DVA
205 * as they are written and migrate onto the arc_mru list.
207 * The ARC_l2c_only state is for buffers that are in the second
208 * level ARC but no longer in any of the ARC_m* lists. The second
209 * level ARC itself may also contain buffers that are in any of
210 * the ARC_m* states - meaning that a buffer can exist in two
211 * places. The reason for the ARC_l2c_only state is to keep the
212 * buffer header in the hash table, so that reads that hit the
213 * second level ARC benefit from these fast lookups.
216 typedef struct arc_state
{
217 list_t arcs_list
[ARC_BUFC_NUMTYPES
]; /* list of evictable buffers */
218 uint64_t arcs_lsize
[ARC_BUFC_NUMTYPES
]; /* amount of evictable data */
219 uint64_t arcs_size
; /* total amount of data in this state */
224 static arc_state_t ARC_anon
;
225 static arc_state_t ARC_mru
;
226 static arc_state_t ARC_mru_ghost
;
227 static arc_state_t ARC_mfu
;
228 static arc_state_t ARC_mfu_ghost
;
229 static arc_state_t ARC_l2c_only
;
231 typedef struct arc_stats
{
232 kstat_named_t arcstat_hits
;
233 kstat_named_t arcstat_misses
;
234 kstat_named_t arcstat_demand_data_hits
;
235 kstat_named_t arcstat_demand_data_misses
;
236 kstat_named_t arcstat_demand_metadata_hits
;
237 kstat_named_t arcstat_demand_metadata_misses
;
238 kstat_named_t arcstat_prefetch_data_hits
;
239 kstat_named_t arcstat_prefetch_data_misses
;
240 kstat_named_t arcstat_prefetch_metadata_hits
;
241 kstat_named_t arcstat_prefetch_metadata_misses
;
242 kstat_named_t arcstat_mru_hits
;
243 kstat_named_t arcstat_mru_ghost_hits
;
244 kstat_named_t arcstat_mfu_hits
;
245 kstat_named_t arcstat_mfu_ghost_hits
;
246 kstat_named_t arcstat_deleted
;
247 kstat_named_t arcstat_recycle_miss
;
248 kstat_named_t arcstat_mutex_miss
;
249 kstat_named_t arcstat_evict_skip
;
250 kstat_named_t arcstat_evict_l2_cached
;
251 kstat_named_t arcstat_evict_l2_eligible
;
252 kstat_named_t arcstat_evict_l2_ineligible
;
253 kstat_named_t arcstat_hash_elements
;
254 kstat_named_t arcstat_hash_elements_max
;
255 kstat_named_t arcstat_hash_collisions
;
256 kstat_named_t arcstat_hash_chains
;
257 kstat_named_t arcstat_hash_chain_max
;
258 kstat_named_t arcstat_p
;
259 kstat_named_t arcstat_c
;
260 kstat_named_t arcstat_c_min
;
261 kstat_named_t arcstat_c_max
;
262 kstat_named_t arcstat_size
;
263 kstat_named_t arcstat_hdr_size
;
264 kstat_named_t arcstat_data_size
;
265 kstat_named_t arcstat_other_size
;
266 kstat_named_t arcstat_l2_hits
;
267 kstat_named_t arcstat_l2_misses
;
268 kstat_named_t arcstat_l2_feeds
;
269 kstat_named_t arcstat_l2_rw_clash
;
270 kstat_named_t arcstat_l2_read_bytes
;
271 kstat_named_t arcstat_l2_write_bytes
;
272 kstat_named_t arcstat_l2_writes_sent
;
273 kstat_named_t arcstat_l2_writes_done
;
274 kstat_named_t arcstat_l2_writes_error
;
275 kstat_named_t arcstat_l2_writes_hdr_miss
;
276 kstat_named_t arcstat_l2_evict_lock_retry
;
277 kstat_named_t arcstat_l2_evict_reading
;
278 kstat_named_t arcstat_l2_free_on_write
;
279 kstat_named_t arcstat_l2_abort_lowmem
;
280 kstat_named_t arcstat_l2_cksum_bad
;
281 kstat_named_t arcstat_l2_io_error
;
282 kstat_named_t arcstat_l2_size
;
283 kstat_named_t arcstat_l2_hdr_size
;
284 kstat_named_t arcstat_memory_throttle_count
;
287 static arc_stats_t arc_stats
= {
288 { "hits", KSTAT_DATA_UINT64
},
289 { "misses", KSTAT_DATA_UINT64
},
290 { "demand_data_hits", KSTAT_DATA_UINT64
},
291 { "demand_data_misses", KSTAT_DATA_UINT64
},
292 { "demand_metadata_hits", KSTAT_DATA_UINT64
},
293 { "demand_metadata_misses", KSTAT_DATA_UINT64
},
294 { "prefetch_data_hits", KSTAT_DATA_UINT64
},
295 { "prefetch_data_misses", KSTAT_DATA_UINT64
},
296 { "prefetch_metadata_hits", KSTAT_DATA_UINT64
},
297 { "prefetch_metadata_misses", KSTAT_DATA_UINT64
},
298 { "mru_hits", KSTAT_DATA_UINT64
},
299 { "mru_ghost_hits", KSTAT_DATA_UINT64
},
300 { "mfu_hits", KSTAT_DATA_UINT64
},
301 { "mfu_ghost_hits", KSTAT_DATA_UINT64
},
302 { "deleted", KSTAT_DATA_UINT64
},
303 { "recycle_miss", KSTAT_DATA_UINT64
},
304 { "mutex_miss", KSTAT_DATA_UINT64
},
305 { "evict_skip", KSTAT_DATA_UINT64
},
306 { "evict_l2_cached", KSTAT_DATA_UINT64
},
307 { "evict_l2_eligible", KSTAT_DATA_UINT64
},
308 { "evict_l2_ineligible", KSTAT_DATA_UINT64
},
309 { "hash_elements", KSTAT_DATA_UINT64
},
310 { "hash_elements_max", KSTAT_DATA_UINT64
},
311 { "hash_collisions", KSTAT_DATA_UINT64
},
312 { "hash_chains", KSTAT_DATA_UINT64
},
313 { "hash_chain_max", KSTAT_DATA_UINT64
},
314 { "p", KSTAT_DATA_UINT64
},
315 { "c", KSTAT_DATA_UINT64
},
316 { "c_min", KSTAT_DATA_UINT64
},
317 { "c_max", KSTAT_DATA_UINT64
},
318 { "size", KSTAT_DATA_UINT64
},
319 { "hdr_size", KSTAT_DATA_UINT64
},
320 { "data_size", KSTAT_DATA_UINT64
},
321 { "other_size", KSTAT_DATA_UINT64
},
322 { "l2_hits", KSTAT_DATA_UINT64
},
323 { "l2_misses", KSTAT_DATA_UINT64
},
324 { "l2_feeds", KSTAT_DATA_UINT64
},
325 { "l2_rw_clash", KSTAT_DATA_UINT64
},
326 { "l2_read_bytes", KSTAT_DATA_UINT64
},
327 { "l2_write_bytes", KSTAT_DATA_UINT64
},
328 { "l2_writes_sent", KSTAT_DATA_UINT64
},
329 { "l2_writes_done", KSTAT_DATA_UINT64
},
330 { "l2_writes_error", KSTAT_DATA_UINT64
},
331 { "l2_writes_hdr_miss", KSTAT_DATA_UINT64
},
332 { "l2_evict_lock_retry", KSTAT_DATA_UINT64
},
333 { "l2_evict_reading", KSTAT_DATA_UINT64
},
334 { "l2_free_on_write", KSTAT_DATA_UINT64
},
335 { "l2_abort_lowmem", KSTAT_DATA_UINT64
},
336 { "l2_cksum_bad", KSTAT_DATA_UINT64
},
337 { "l2_io_error", KSTAT_DATA_UINT64
},
338 { "l2_size", KSTAT_DATA_UINT64
},
339 { "l2_hdr_size", KSTAT_DATA_UINT64
},
340 { "memory_throttle_count", KSTAT_DATA_UINT64
}
343 #define ARCSTAT(stat) (arc_stats.stat.value.ui64)
345 #define ARCSTAT_INCR(stat, val) \
346 atomic_add_64(&arc_stats.stat.value.ui64, (val));
348 #define ARCSTAT_BUMP(stat) ARCSTAT_INCR(stat, 1)
349 #define ARCSTAT_BUMPDOWN(stat) ARCSTAT_INCR(stat, -1)
351 #define ARCSTAT_MAX(stat, val) { \
353 while ((val) > (m = arc_stats.stat.value.ui64) && \
354 (m != atomic_cas_64(&arc_stats.stat.value.ui64, m, (val)))) \
358 #define ARCSTAT_MAXSTAT(stat) \
359 ARCSTAT_MAX(stat##_max, arc_stats.stat.value.ui64)
362 * We define a macro to allow ARC hits/misses to be easily broken down by
363 * two separate conditions, giving a total of four different subtypes for
364 * each of hits and misses (so eight statistics total).
366 #define ARCSTAT_CONDSTAT(cond1, stat1, notstat1, cond2, stat2, notstat2, stat) \
369 ARCSTAT_BUMP(arcstat_##stat1##_##stat2##_##stat); \
371 ARCSTAT_BUMP(arcstat_##stat1##_##notstat2##_##stat); \
375 ARCSTAT_BUMP(arcstat_##notstat1##_##stat2##_##stat); \
377 ARCSTAT_BUMP(arcstat_##notstat1##_##notstat2##_##stat);\
382 static arc_state_t
*arc_anon
;
383 static arc_state_t
*arc_mru
;
384 static arc_state_t
*arc_mru_ghost
;
385 static arc_state_t
*arc_mfu
;
386 static arc_state_t
*arc_mfu_ghost
;
387 static arc_state_t
*arc_l2c_only
;
390 * There are several ARC variables that are critical to export as kstats --
391 * but we don't want to have to grovel around in the kstat whenever we wish to
392 * manipulate them. For these variables, we therefore define them to be in
393 * terms of the statistic variable. This assures that we are not introducing
394 * the possibility of inconsistency by having shadow copies of the variables,
395 * while still allowing the code to be readable.
397 #define arc_size ARCSTAT(arcstat_size) /* actual total arc size */
398 #define arc_p ARCSTAT(arcstat_p) /* target size of MRU */
399 #define arc_c ARCSTAT(arcstat_c) /* target size of cache */
400 #define arc_c_min ARCSTAT(arcstat_c_min) /* min target cache size */
401 #define arc_c_max ARCSTAT(arcstat_c_max) /* max target cache size */
403 static int arc_no_grow
; /* Don't try to grow cache size */
404 static uint64_t arc_tempreserve
;
405 static uint64_t arc_loaned_bytes
;
406 static uint64_t arc_meta_used
;
407 static uint64_t arc_meta_limit
;
408 static uint64_t arc_meta_max
= 0;
410 typedef struct l2arc_buf_hdr l2arc_buf_hdr_t
;
412 typedef struct arc_callback arc_callback_t
;
414 struct arc_callback
{
416 arc_done_func_t
*acb_done
;
418 zio_t
*acb_zio_dummy
;
419 arc_callback_t
*acb_next
;
422 typedef struct arc_write_callback arc_write_callback_t
;
424 struct arc_write_callback
{
426 arc_done_func_t
*awcb_ready
;
427 arc_done_func_t
*awcb_done
;
432 /* protected by hash lock */
437 kmutex_t b_freeze_lock
;
438 zio_cksum_t
*b_freeze_cksum
;
441 arc_buf_hdr_t
*b_hash_next
;
446 arc_callback_t
*b_acb
;
450 arc_buf_contents_t b_type
;
454 /* protected by arc state mutex */
455 arc_state_t
*b_state
;
456 list_node_t b_arc_node
;
458 /* updated atomically */
459 clock_t b_arc_access
;
461 /* self protecting */
464 l2arc_buf_hdr_t
*b_l2hdr
;
465 list_node_t b_l2node
;
468 static arc_buf_t
*arc_eviction_list
;
469 static kmutex_t arc_eviction_mtx
;
470 static arc_buf_hdr_t arc_eviction_hdr
;
471 static void arc_get_data_buf(arc_buf_t
*buf
);
472 static void arc_access(arc_buf_hdr_t
*buf
, kmutex_t
*hash_lock
);
473 static int arc_evict_needed(arc_buf_contents_t type
);
474 static void arc_evict_ghost(arc_state_t
*state
, uint64_t spa
, int64_t bytes
);
476 static boolean_t
l2arc_write_eligible(uint64_t spa_guid
, arc_buf_hdr_t
*ab
);
478 #define GHOST_STATE(state) \
479 ((state) == arc_mru_ghost || (state) == arc_mfu_ghost || \
480 (state) == arc_l2c_only)
483 * Private ARC flags. These flags are private ARC only flags that will show up
484 * in b_flags in the arc_hdr_buf_t. Some flags are publicly declared, and can
485 * be passed in as arc_flags in things like arc_read. However, these flags
486 * should never be passed and should only be set by ARC code. When adding new
487 * public flags, make sure not to smash the private ones.
490 #define ARC_IN_HASH_TABLE (1 << 9) /* this buffer is hashed */
491 #define ARC_IO_IN_PROGRESS (1 << 10) /* I/O in progress for buf */
492 #define ARC_IO_ERROR (1 << 11) /* I/O failed for buf */
493 #define ARC_FREED_IN_READ (1 << 12) /* buf freed while in read */
494 #define ARC_BUF_AVAILABLE (1 << 13) /* block not in active use */
495 #define ARC_INDIRECT (1 << 14) /* this is an indirect block */
496 #define ARC_FREE_IN_PROGRESS (1 << 15) /* hdr about to be freed */
497 #define ARC_L2_WRITING (1 << 16) /* L2ARC write in progress */
498 #define ARC_L2_EVICTED (1 << 17) /* evicted during I/O */
499 #define ARC_L2_WRITE_HEAD (1 << 18) /* head of write list */
501 #define HDR_IN_HASH_TABLE(hdr) ((hdr)->b_flags & ARC_IN_HASH_TABLE)
502 #define HDR_IO_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_IO_IN_PROGRESS)
503 #define HDR_IO_ERROR(hdr) ((hdr)->b_flags & ARC_IO_ERROR)
504 #define HDR_PREFETCH(hdr) ((hdr)->b_flags & ARC_PREFETCH)
505 #define HDR_FREED_IN_READ(hdr) ((hdr)->b_flags & ARC_FREED_IN_READ)
506 #define HDR_BUF_AVAILABLE(hdr) ((hdr)->b_flags & ARC_BUF_AVAILABLE)
507 #define HDR_FREE_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_FREE_IN_PROGRESS)
508 #define HDR_L2CACHE(hdr) ((hdr)->b_flags & ARC_L2CACHE)
509 #define HDR_L2_READING(hdr) ((hdr)->b_flags & ARC_IO_IN_PROGRESS && \
510 (hdr)->b_l2hdr != NULL)
511 #define HDR_L2_WRITING(hdr) ((hdr)->b_flags & ARC_L2_WRITING)
512 #define HDR_L2_EVICTED(hdr) ((hdr)->b_flags & ARC_L2_EVICTED)
513 #define HDR_L2_WRITE_HEAD(hdr) ((hdr)->b_flags & ARC_L2_WRITE_HEAD)
519 #define HDR_SIZE ((int64_t)sizeof (arc_buf_hdr_t))
520 #define L2HDR_SIZE ((int64_t)sizeof (l2arc_buf_hdr_t))
523 * Hash table routines
526 #define HT_LOCK_PAD 64
531 unsigned char pad
[(HT_LOCK_PAD
- sizeof (kmutex_t
))];
535 #define BUF_LOCKS 256
536 typedef struct buf_hash_table
{
538 arc_buf_hdr_t
**ht_table
;
539 struct ht_lock ht_locks
[BUF_LOCKS
];
542 static buf_hash_table_t buf_hash_table
;
544 #define BUF_HASH_INDEX(spa, dva, birth) \
545 (buf_hash(spa, dva, birth) & buf_hash_table.ht_mask)
546 #define BUF_HASH_LOCK_NTRY(idx) (buf_hash_table.ht_locks[idx & (BUF_LOCKS-1)])
547 #define BUF_HASH_LOCK(idx) (&(BUF_HASH_LOCK_NTRY(idx).ht_lock))
548 #define HDR_LOCK(hdr) \
549 (BUF_HASH_LOCK(BUF_HASH_INDEX(hdr->b_spa, &hdr->b_dva, hdr->b_birth)))
551 uint64_t zfs_crc64_table
[256];
557 #define L2ARC_WRITE_SIZE (8 * 1024 * 1024) /* initial write max */
558 #define L2ARC_HEADROOM 2 /* num of writes */
559 #define L2ARC_FEED_SECS 1 /* caching interval secs */
560 #define L2ARC_FEED_MIN_MS 200 /* min caching interval ms */
562 #define l2arc_writes_sent ARCSTAT(arcstat_l2_writes_sent)
563 #define l2arc_writes_done ARCSTAT(arcstat_l2_writes_done)
566 * L2ARC Performance Tunables
568 uint64_t l2arc_write_max
= L2ARC_WRITE_SIZE
; /* default max write size */
569 uint64_t l2arc_write_boost
= L2ARC_WRITE_SIZE
; /* extra write during warmup */
570 uint64_t l2arc_headroom
= L2ARC_HEADROOM
; /* number of dev writes */
571 uint64_t l2arc_feed_secs
= L2ARC_FEED_SECS
; /* interval seconds */
572 uint64_t l2arc_feed_min_ms
= L2ARC_FEED_MIN_MS
; /* min interval milliseconds */
573 boolean_t l2arc_noprefetch
= B_TRUE
; /* don't cache prefetch bufs */
574 boolean_t l2arc_feed_again
= B_TRUE
; /* turbo warmup */
575 boolean_t l2arc_norw
= B_TRUE
; /* no reads during writes */
580 typedef struct l2arc_dev
{
581 vdev_t
*l2ad_vdev
; /* vdev */
582 spa_t
*l2ad_spa
; /* spa */
583 uint64_t l2ad_hand
; /* next write location */
584 uint64_t l2ad_write
; /* desired write size, bytes */
585 uint64_t l2ad_boost
; /* warmup write boost, bytes */
586 uint64_t l2ad_start
; /* first addr on device */
587 uint64_t l2ad_end
; /* last addr on device */
588 uint64_t l2ad_evict
; /* last addr eviction reached */
589 boolean_t l2ad_first
; /* first sweep through */
590 boolean_t l2ad_writing
; /* currently writing */
591 list_t
*l2ad_buflist
; /* buffer list */
592 list_node_t l2ad_node
; /* device list node */
595 static list_t L2ARC_dev_list
; /* device list */
596 static list_t
*l2arc_dev_list
; /* device list pointer */
597 static kmutex_t l2arc_dev_mtx
; /* device list mutex */
598 static l2arc_dev_t
*l2arc_dev_last
; /* last device used */
599 static kmutex_t l2arc_buflist_mtx
; /* mutex for all buflists */
600 static list_t L2ARC_free_on_write
; /* free after write buf list */
601 static list_t
*l2arc_free_on_write
; /* free after write list ptr */
602 static kmutex_t l2arc_free_on_write_mtx
; /* mutex for list */
603 static uint64_t l2arc_ndev
; /* number of devices */
605 typedef struct l2arc_read_callback
{
606 arc_buf_t
*l2rcb_buf
; /* read buffer */
607 spa_t
*l2rcb_spa
; /* spa */
608 blkptr_t l2rcb_bp
; /* original blkptr */
609 zbookmark_t l2rcb_zb
; /* original bookmark */
610 int l2rcb_flags
; /* original flags */
611 } l2arc_read_callback_t
;
613 typedef struct l2arc_write_callback
{
614 l2arc_dev_t
*l2wcb_dev
; /* device info */
615 arc_buf_hdr_t
*l2wcb_head
; /* head of write buflist */
616 } l2arc_write_callback_t
;
618 struct l2arc_buf_hdr
{
619 /* protected by arc_buf_hdr mutex */
620 l2arc_dev_t
*b_dev
; /* L2ARC device */
621 uint64_t b_daddr
; /* disk address, offset byte */
624 typedef struct l2arc_data_free
{
625 /* protected by l2arc_free_on_write_mtx */
628 void (*l2df_func
)(void *, size_t);
629 list_node_t l2df_list_node
;
632 static kmutex_t l2arc_feed_thr_lock
;
633 static kcondvar_t l2arc_feed_thr_cv
;
634 static uint8_t l2arc_thread_exit
;
636 static void l2arc_read_done(zio_t
*zio
);
637 static void l2arc_hdr_stat_add(void);
638 static void l2arc_hdr_stat_remove(void);
641 buf_hash(uint64_t spa
, const dva_t
*dva
, uint64_t birth
)
643 uint8_t *vdva
= (uint8_t *)dva
;
644 uint64_t crc
= -1ULL;
647 ASSERT(zfs_crc64_table
[128] == ZFS_CRC64_POLY
);
649 for (i
= 0; i
< sizeof (dva_t
); i
++)
650 crc
= (crc
>> 8) ^ zfs_crc64_table
[(crc
^ vdva
[i
]) & 0xFF];
652 crc
^= (spa
>>8) ^ birth
;
657 #define BUF_EMPTY(buf) \
658 ((buf)->b_dva.dva_word[0] == 0 && \
659 (buf)->b_dva.dva_word[1] == 0 && \
662 #define BUF_EQUAL(spa, dva, birth, buf) \
663 ((buf)->b_dva.dva_word[0] == (dva)->dva_word[0]) && \
664 ((buf)->b_dva.dva_word[1] == (dva)->dva_word[1]) && \
665 ((buf)->b_birth == birth) && ((buf)->b_spa == spa)
668 buf_discard_identity(arc_buf_hdr_t
*hdr
)
670 hdr
->b_dva
.dva_word
[0] = 0;
671 hdr
->b_dva
.dva_word
[1] = 0;
676 static arc_buf_hdr_t
*
677 buf_hash_find(uint64_t spa
, const dva_t
*dva
, uint64_t birth
, kmutex_t
**lockp
)
679 uint64_t idx
= BUF_HASH_INDEX(spa
, dva
, birth
);
680 kmutex_t
*hash_lock
= BUF_HASH_LOCK(idx
);
683 mutex_enter(hash_lock
);
684 for (buf
= buf_hash_table
.ht_table
[idx
]; buf
!= NULL
;
685 buf
= buf
->b_hash_next
) {
686 if (BUF_EQUAL(spa
, dva
, birth
, buf
)) {
691 mutex_exit(hash_lock
);
697 * Insert an entry into the hash table. If there is already an element
698 * equal to elem in the hash table, then the already existing element
699 * will be returned and the new element will not be inserted.
700 * Otherwise returns NULL.
702 static arc_buf_hdr_t
*
703 buf_hash_insert(arc_buf_hdr_t
*buf
, kmutex_t
**lockp
)
705 uint64_t idx
= BUF_HASH_INDEX(buf
->b_spa
, &buf
->b_dva
, buf
->b_birth
);
706 kmutex_t
*hash_lock
= BUF_HASH_LOCK(idx
);
710 ASSERT(!HDR_IN_HASH_TABLE(buf
));
712 mutex_enter(hash_lock
);
713 for (fbuf
= buf_hash_table
.ht_table
[idx
], i
= 0; fbuf
!= NULL
;
714 fbuf
= fbuf
->b_hash_next
, i
++) {
715 if (BUF_EQUAL(buf
->b_spa
, &buf
->b_dva
, buf
->b_birth
, fbuf
))
719 buf
->b_hash_next
= buf_hash_table
.ht_table
[idx
];
720 buf_hash_table
.ht_table
[idx
] = buf
;
721 buf
->b_flags
|= ARC_IN_HASH_TABLE
;
723 /* collect some hash table performance data */
725 ARCSTAT_BUMP(arcstat_hash_collisions
);
727 ARCSTAT_BUMP(arcstat_hash_chains
);
729 ARCSTAT_MAX(arcstat_hash_chain_max
, i
);
732 ARCSTAT_BUMP(arcstat_hash_elements
);
733 ARCSTAT_MAXSTAT(arcstat_hash_elements
);
739 buf_hash_remove(arc_buf_hdr_t
*buf
)
741 arc_buf_hdr_t
*fbuf
, **bufp
;
742 uint64_t idx
= BUF_HASH_INDEX(buf
->b_spa
, &buf
->b_dva
, buf
->b_birth
);
744 ASSERT(MUTEX_HELD(BUF_HASH_LOCK(idx
)));
745 ASSERT(HDR_IN_HASH_TABLE(buf
));
747 bufp
= &buf_hash_table
.ht_table
[idx
];
748 while ((fbuf
= *bufp
) != buf
) {
749 ASSERT(fbuf
!= NULL
);
750 bufp
= &fbuf
->b_hash_next
;
752 *bufp
= buf
->b_hash_next
;
753 buf
->b_hash_next
= NULL
;
754 buf
->b_flags
&= ~ARC_IN_HASH_TABLE
;
756 /* collect some hash table performance data */
757 ARCSTAT_BUMPDOWN(arcstat_hash_elements
);
759 if (buf_hash_table
.ht_table
[idx
] &&
760 buf_hash_table
.ht_table
[idx
]->b_hash_next
== NULL
)
761 ARCSTAT_BUMPDOWN(arcstat_hash_chains
);
765 * Global data structures and functions for the buf kmem cache.
767 static kmem_cache_t
*hdr_cache
;
768 static kmem_cache_t
*buf_cache
;
775 kmem_free(buf_hash_table
.ht_table
,
776 (buf_hash_table
.ht_mask
+ 1) * sizeof (void *));
777 for (i
= 0; i
< BUF_LOCKS
; i
++)
778 mutex_destroy(&buf_hash_table
.ht_locks
[i
].ht_lock
);
779 kmem_cache_destroy(hdr_cache
);
780 kmem_cache_destroy(buf_cache
);
784 * Constructor callback - called when the cache is empty
785 * and a new buf is requested.
789 hdr_cons(void *vbuf
, void *unused
, int kmflag
)
791 arc_buf_hdr_t
*buf
= vbuf
;
793 bzero(buf
, sizeof (arc_buf_hdr_t
));
794 refcount_create(&buf
->b_refcnt
);
795 cv_init(&buf
->b_cv
, NULL
, CV_DEFAULT
, NULL
);
796 mutex_init(&buf
->b_freeze_lock
, NULL
, MUTEX_DEFAULT
, NULL
);
797 arc_space_consume(sizeof (arc_buf_hdr_t
), ARC_SPACE_HDRS
);
804 buf_cons(void *vbuf
, void *unused
, int kmflag
)
806 arc_buf_t
*buf
= vbuf
;
808 bzero(buf
, sizeof (arc_buf_t
));
809 mutex_init(&buf
->b_evict_lock
, NULL
, MUTEX_DEFAULT
, NULL
);
810 rw_init(&buf
->b_data_lock
, NULL
, RW_DEFAULT
, NULL
);
811 arc_space_consume(sizeof (arc_buf_t
), ARC_SPACE_HDRS
);
817 * Destructor callback - called when a cached buf is
818 * no longer required.
822 hdr_dest(void *vbuf
, void *unused
)
824 arc_buf_hdr_t
*buf
= vbuf
;
826 ASSERT(BUF_EMPTY(buf
));
827 refcount_destroy(&buf
->b_refcnt
);
828 cv_destroy(&buf
->b_cv
);
829 mutex_destroy(&buf
->b_freeze_lock
);
830 arc_space_return(sizeof (arc_buf_hdr_t
), ARC_SPACE_HDRS
);
835 buf_dest(void *vbuf
, void *unused
)
837 arc_buf_t
*buf
= vbuf
;
839 mutex_destroy(&buf
->b_evict_lock
);
840 rw_destroy(&buf
->b_data_lock
);
841 arc_space_return(sizeof (arc_buf_t
), ARC_SPACE_HDRS
);
845 * Reclaim callback -- invoked when memory is low.
849 hdr_recl(void *unused
)
851 dprintf("hdr_recl called\n");
853 * umem calls the reclaim func when we destroy the buf cache,
854 * which is after we do arc_fini().
857 cv_signal(&arc_reclaim_thr_cv
);
864 uint64_t hsize
= 1ULL << 12;
868 * The hash table is big enough to fill all of physical memory
869 * with an average 64K block size. The table will take up
870 * totalmem*sizeof(void*)/64K (eg. 128KB/GB with 8-byte pointers).
872 while (hsize
* 65536 < physmem
* PAGESIZE
)
875 buf_hash_table
.ht_mask
= hsize
- 1;
876 buf_hash_table
.ht_table
=
877 kmem_zalloc(hsize
* sizeof (void*), KM_NOSLEEP
);
878 if (buf_hash_table
.ht_table
== NULL
) {
879 ASSERT(hsize
> (1ULL << 8));
884 hdr_cache
= kmem_cache_create("arc_buf_hdr_t", sizeof (arc_buf_hdr_t
),
885 0, hdr_cons
, hdr_dest
, hdr_recl
, NULL
, NULL
, 0);
886 buf_cache
= kmem_cache_create("arc_buf_t", sizeof (arc_buf_t
),
887 0, buf_cons
, buf_dest
, NULL
, NULL
, NULL
, 0);
889 for (i
= 0; i
< 256; i
++)
890 for (ct
= zfs_crc64_table
+ i
, *ct
= i
, j
= 8; j
> 0; j
--)
891 *ct
= (*ct
>> 1) ^ (-(*ct
& 1) & ZFS_CRC64_POLY
);
893 for (i
= 0; i
< BUF_LOCKS
; i
++) {
894 mutex_init(&buf_hash_table
.ht_locks
[i
].ht_lock
,
895 NULL
, MUTEX_DEFAULT
, NULL
);
899 #define ARC_MINTIME (hz>>4) /* 62 ms */
902 arc_cksum_verify(arc_buf_t
*buf
)
906 if (!(zfs_flags
& ZFS_DEBUG_MODIFY
))
909 mutex_enter(&buf
->b_hdr
->b_freeze_lock
);
910 if (buf
->b_hdr
->b_freeze_cksum
== NULL
||
911 (buf
->b_hdr
->b_flags
& ARC_IO_ERROR
)) {
912 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
915 fletcher_2_native(buf
->b_data
, buf
->b_hdr
->b_size
, &zc
);
916 if (!ZIO_CHECKSUM_EQUAL(*buf
->b_hdr
->b_freeze_cksum
, zc
))
917 panic("buffer modified while frozen!");
918 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
922 arc_cksum_equal(arc_buf_t
*buf
)
927 mutex_enter(&buf
->b_hdr
->b_freeze_lock
);
928 fletcher_2_native(buf
->b_data
, buf
->b_hdr
->b_size
, &zc
);
929 equal
= ZIO_CHECKSUM_EQUAL(*buf
->b_hdr
->b_freeze_cksum
, zc
);
930 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
936 arc_cksum_compute(arc_buf_t
*buf
, boolean_t force
)
938 if (!force
&& !(zfs_flags
& ZFS_DEBUG_MODIFY
))
941 mutex_enter(&buf
->b_hdr
->b_freeze_lock
);
942 if (buf
->b_hdr
->b_freeze_cksum
!= NULL
) {
943 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
946 buf
->b_hdr
->b_freeze_cksum
= kmem_alloc(sizeof (zio_cksum_t
), KM_SLEEP
);
947 fletcher_2_native(buf
->b_data
, buf
->b_hdr
->b_size
,
948 buf
->b_hdr
->b_freeze_cksum
);
949 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
953 arc_buf_thaw(arc_buf_t
*buf
)
955 if (zfs_flags
& ZFS_DEBUG_MODIFY
) {
956 if (buf
->b_hdr
->b_state
!= arc_anon
)
957 panic("modifying non-anon buffer!");
958 if (buf
->b_hdr
->b_flags
& ARC_IO_IN_PROGRESS
)
959 panic("modifying buffer while i/o in progress!");
960 arc_cksum_verify(buf
);
963 mutex_enter(&buf
->b_hdr
->b_freeze_lock
);
964 if (buf
->b_hdr
->b_freeze_cksum
!= NULL
) {
965 kmem_free(buf
->b_hdr
->b_freeze_cksum
, sizeof (zio_cksum_t
));
966 buf
->b_hdr
->b_freeze_cksum
= NULL
;
969 if (zfs_flags
& ZFS_DEBUG_MODIFY
) {
970 if (buf
->b_hdr
->b_thawed
)
971 kmem_free(buf
->b_hdr
->b_thawed
, 1);
972 buf
->b_hdr
->b_thawed
= kmem_alloc(1, KM_SLEEP
);
975 mutex_exit(&buf
->b_hdr
->b_freeze_lock
);
979 arc_buf_freeze(arc_buf_t
*buf
)
983 if (!(zfs_flags
& ZFS_DEBUG_MODIFY
))
986 hash_lock
= HDR_LOCK(buf
->b_hdr
);
987 mutex_enter(hash_lock
);
989 ASSERT(buf
->b_hdr
->b_freeze_cksum
!= NULL
||
990 buf
->b_hdr
->b_state
== arc_anon
);
991 arc_cksum_compute(buf
, B_FALSE
);
992 mutex_exit(hash_lock
);
996 add_reference(arc_buf_hdr_t
*ab
, kmutex_t
*hash_lock
, void *tag
)
998 ASSERT(MUTEX_HELD(hash_lock
));
1000 if ((refcount_add(&ab
->b_refcnt
, tag
) == 1) &&
1001 (ab
->b_state
!= arc_anon
)) {
1002 uint64_t delta
= ab
->b_size
* ab
->b_datacnt
;
1003 list_t
*list
= &ab
->b_state
->arcs_list
[ab
->b_type
];
1004 uint64_t *size
= &ab
->b_state
->arcs_lsize
[ab
->b_type
];
1006 ASSERT(!MUTEX_HELD(&ab
->b_state
->arcs_mtx
));
1007 mutex_enter(&ab
->b_state
->arcs_mtx
);
1008 ASSERT(list_link_active(&ab
->b_arc_node
));
1009 list_remove(list
, ab
);
1010 if (GHOST_STATE(ab
->b_state
)) {
1011 ASSERT3U(ab
->b_datacnt
, ==, 0);
1012 ASSERT3P(ab
->b_buf
, ==, NULL
);
1016 ASSERT3U(*size
, >=, delta
);
1017 atomic_add_64(size
, -delta
);
1018 mutex_exit(&ab
->b_state
->arcs_mtx
);
1019 /* remove the prefetch flag if we get a reference */
1020 if (ab
->b_flags
& ARC_PREFETCH
)
1021 ab
->b_flags
&= ~ARC_PREFETCH
;
1026 remove_reference(arc_buf_hdr_t
*ab
, kmutex_t
*hash_lock
, void *tag
)
1029 arc_state_t
*state
= ab
->b_state
;
1031 ASSERT(state
== arc_anon
|| MUTEX_HELD(hash_lock
));
1032 ASSERT(!GHOST_STATE(state
));
1034 if (((cnt
= refcount_remove(&ab
->b_refcnt
, tag
)) == 0) &&
1035 (state
!= arc_anon
)) {
1036 uint64_t *size
= &state
->arcs_lsize
[ab
->b_type
];
1038 ASSERT(!MUTEX_HELD(&state
->arcs_mtx
));
1039 mutex_enter(&state
->arcs_mtx
);
1040 ASSERT(!list_link_active(&ab
->b_arc_node
));
1041 list_insert_head(&state
->arcs_list
[ab
->b_type
], ab
);
1042 ASSERT(ab
->b_datacnt
> 0);
1043 atomic_add_64(size
, ab
->b_size
* ab
->b_datacnt
);
1044 mutex_exit(&state
->arcs_mtx
);
1050 * Move the supplied buffer to the indicated state. The mutex
1051 * for the buffer must be held by the caller.
1054 arc_change_state(arc_state_t
*new_state
, arc_buf_hdr_t
*ab
, kmutex_t
*hash_lock
)
1056 arc_state_t
*old_state
= ab
->b_state
;
1057 int64_t refcnt
= refcount_count(&ab
->b_refcnt
);
1058 uint64_t from_delta
, to_delta
;
1060 ASSERT(MUTEX_HELD(hash_lock
));
1061 ASSERT(new_state
!= old_state
);
1062 ASSERT(refcnt
== 0 || ab
->b_datacnt
> 0);
1063 ASSERT(ab
->b_datacnt
== 0 || !GHOST_STATE(new_state
));
1064 ASSERT(ab
->b_datacnt
<= 1 || old_state
!= arc_anon
);
1066 from_delta
= to_delta
= ab
->b_datacnt
* ab
->b_size
;
1069 * If this buffer is evictable, transfer it from the
1070 * old state list to the new state list.
1073 if (old_state
!= arc_anon
) {
1074 int use_mutex
= !MUTEX_HELD(&old_state
->arcs_mtx
);
1075 uint64_t *size
= &old_state
->arcs_lsize
[ab
->b_type
];
1078 mutex_enter(&old_state
->arcs_mtx
);
1080 ASSERT(list_link_active(&ab
->b_arc_node
));
1081 list_remove(&old_state
->arcs_list
[ab
->b_type
], ab
);
1084 * If prefetching out of the ghost cache,
1085 * we will have a non-zero datacnt.
1087 if (GHOST_STATE(old_state
) && ab
->b_datacnt
== 0) {
1088 /* ghost elements have a ghost size */
1089 ASSERT(ab
->b_buf
== NULL
);
1090 from_delta
= ab
->b_size
;
1092 ASSERT3U(*size
, >=, from_delta
);
1093 atomic_add_64(size
, -from_delta
);
1096 mutex_exit(&old_state
->arcs_mtx
);
1098 if (new_state
!= arc_anon
) {
1099 int use_mutex
= !MUTEX_HELD(&new_state
->arcs_mtx
);
1100 uint64_t *size
= &new_state
->arcs_lsize
[ab
->b_type
];
1103 mutex_enter(&new_state
->arcs_mtx
);
1105 list_insert_head(&new_state
->arcs_list
[ab
->b_type
], ab
);
1107 /* ghost elements have a ghost size */
1108 if (GHOST_STATE(new_state
)) {
1109 ASSERT(ab
->b_datacnt
== 0);
1110 ASSERT(ab
->b_buf
== NULL
);
1111 to_delta
= ab
->b_size
;
1113 atomic_add_64(size
, to_delta
);
1116 mutex_exit(&new_state
->arcs_mtx
);
1120 ASSERT(!BUF_EMPTY(ab
));
1121 if (new_state
== arc_anon
&& HDR_IN_HASH_TABLE(ab
))
1122 buf_hash_remove(ab
);
1124 /* adjust state sizes */
1126 atomic_add_64(&new_state
->arcs_size
, to_delta
);
1128 ASSERT3U(old_state
->arcs_size
, >=, from_delta
);
1129 atomic_add_64(&old_state
->arcs_size
, -from_delta
);
1131 ab
->b_state
= new_state
;
1133 /* adjust l2arc hdr stats */
1134 if (new_state
== arc_l2c_only
)
1135 l2arc_hdr_stat_add();
1136 else if (old_state
== arc_l2c_only
)
1137 l2arc_hdr_stat_remove();
1141 arc_space_consume(uint64_t space
, arc_space_type_t type
)
1143 ASSERT(type
>= 0 && type
< ARC_SPACE_NUMTYPES
);
1148 case ARC_SPACE_DATA
:
1149 ARCSTAT_INCR(arcstat_data_size
, space
);
1151 case ARC_SPACE_OTHER
:
1152 ARCSTAT_INCR(arcstat_other_size
, space
);
1154 case ARC_SPACE_HDRS
:
1155 ARCSTAT_INCR(arcstat_hdr_size
, space
);
1157 case ARC_SPACE_L2HDRS
:
1158 ARCSTAT_INCR(arcstat_l2_hdr_size
, space
);
1162 atomic_add_64(&arc_meta_used
, space
);
1163 atomic_add_64(&arc_size
, space
);
1167 arc_space_return(uint64_t space
, arc_space_type_t type
)
1169 ASSERT(type
>= 0 && type
< ARC_SPACE_NUMTYPES
);
1174 case ARC_SPACE_DATA
:
1175 ARCSTAT_INCR(arcstat_data_size
, -space
);
1177 case ARC_SPACE_OTHER
:
1178 ARCSTAT_INCR(arcstat_other_size
, -space
);
1180 case ARC_SPACE_HDRS
:
1181 ARCSTAT_INCR(arcstat_hdr_size
, -space
);
1183 case ARC_SPACE_L2HDRS
:
1184 ARCSTAT_INCR(arcstat_l2_hdr_size
, -space
);
1188 ASSERT(arc_meta_used
>= space
);
1189 if (arc_meta_max
< arc_meta_used
)
1190 arc_meta_max
= arc_meta_used
;
1191 atomic_add_64(&arc_meta_used
, -space
);
1192 ASSERT(arc_size
>= space
);
1193 atomic_add_64(&arc_size
, -space
);
1197 arc_data_buf_alloc(uint64_t size
)
1199 if (arc_evict_needed(ARC_BUFC_DATA
))
1200 cv_signal(&arc_reclaim_thr_cv
);
1201 atomic_add_64(&arc_size
, size
);
1202 return (zio_data_buf_alloc(size
));
1206 arc_data_buf_free(void *buf
, uint64_t size
)
1208 zio_data_buf_free(buf
, size
);
1209 ASSERT(arc_size
>= size
);
1210 atomic_add_64(&arc_size
, -size
);
1214 arc_buf_alloc(spa_t
*spa
, int size
, void *tag
, arc_buf_contents_t type
)
1219 ASSERT3U(size
, >, 0);
1220 hdr
= kmem_cache_alloc(hdr_cache
, KM_PUSHPAGE
);
1221 ASSERT(BUF_EMPTY(hdr
));
1224 hdr
->b_spa
= spa_guid(spa
);
1225 hdr
->b_state
= arc_anon
;
1226 hdr
->b_arc_access
= 0;
1227 buf
= kmem_cache_alloc(buf_cache
, KM_PUSHPAGE
);
1230 buf
->b_efunc
= NULL
;
1231 buf
->b_private
= NULL
;
1234 arc_get_data_buf(buf
);
1237 ASSERT(refcount_is_zero(&hdr
->b_refcnt
));
1238 (void) refcount_add(&hdr
->b_refcnt
, tag
);
1243 static char *arc_onloan_tag
= "onloan";
1246 * Loan out an anonymous arc buffer. Loaned buffers are not counted as in
1247 * flight data by arc_tempreserve_space() until they are "returned". Loaned
1248 * buffers must be returned to the arc before they can be used by the DMU or
1252 arc_loan_buf(spa_t
*spa
, int size
)
1256 buf
= arc_buf_alloc(spa
, size
, arc_onloan_tag
, ARC_BUFC_DATA
);
1258 atomic_add_64(&arc_loaned_bytes
, size
);
1263 * Return a loaned arc buffer to the arc.
1266 arc_return_buf(arc_buf_t
*buf
, void *tag
)
1268 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
1270 ASSERT(buf
->b_data
!= NULL
);
1271 (void) refcount_add(&hdr
->b_refcnt
, tag
);
1272 (void) refcount_remove(&hdr
->b_refcnt
, arc_onloan_tag
);
1274 atomic_add_64(&arc_loaned_bytes
, -hdr
->b_size
);
1277 /* Detach an arc_buf from a dbuf (tag) */
1279 arc_loan_inuse_buf(arc_buf_t
*buf
, void *tag
)
1283 ASSERT(buf
->b_data
!= NULL
);
1285 (void) refcount_add(&hdr
->b_refcnt
, arc_onloan_tag
);
1286 (void) refcount_remove(&hdr
->b_refcnt
, tag
);
1287 buf
->b_efunc
= NULL
;
1288 buf
->b_private
= NULL
;
1290 atomic_add_64(&arc_loaned_bytes
, hdr
->b_size
);
1294 arc_buf_clone(arc_buf_t
*from
)
1297 arc_buf_hdr_t
*hdr
= from
->b_hdr
;
1298 uint64_t size
= hdr
->b_size
;
1300 ASSERT(hdr
->b_state
!= arc_anon
);
1302 buf
= kmem_cache_alloc(buf_cache
, KM_PUSHPAGE
);
1305 buf
->b_efunc
= NULL
;
1306 buf
->b_private
= NULL
;
1307 buf
->b_next
= hdr
->b_buf
;
1309 arc_get_data_buf(buf
);
1310 bcopy(from
->b_data
, buf
->b_data
, size
);
1311 hdr
->b_datacnt
+= 1;
1316 arc_buf_add_ref(arc_buf_t
*buf
, void* tag
)
1319 kmutex_t
*hash_lock
;
1322 * Check to see if this buffer is evicted. Callers
1323 * must verify b_data != NULL to know if the add_ref
1326 mutex_enter(&buf
->b_evict_lock
);
1327 if (buf
->b_data
== NULL
) {
1328 mutex_exit(&buf
->b_evict_lock
);
1331 hash_lock
= HDR_LOCK(buf
->b_hdr
);
1332 mutex_enter(hash_lock
);
1334 ASSERT3P(hash_lock
, ==, HDR_LOCK(hdr
));
1335 mutex_exit(&buf
->b_evict_lock
);
1337 ASSERT(hdr
->b_state
== arc_mru
|| hdr
->b_state
== arc_mfu
);
1338 add_reference(hdr
, hash_lock
, tag
);
1339 DTRACE_PROBE1(arc__hit
, arc_buf_hdr_t
*, hdr
);
1340 arc_access(hdr
, hash_lock
);
1341 mutex_exit(hash_lock
);
1342 ARCSTAT_BUMP(arcstat_hits
);
1343 ARCSTAT_CONDSTAT(!(hdr
->b_flags
& ARC_PREFETCH
),
1344 demand
, prefetch
, hdr
->b_type
!= ARC_BUFC_METADATA
,
1345 data
, metadata
, hits
);
1349 * Free the arc data buffer. If it is an l2arc write in progress,
1350 * the buffer is placed on l2arc_free_on_write to be freed later.
1353 arc_buf_data_free(arc_buf_hdr_t
*hdr
, void (*free_func
)(void *, size_t),
1354 void *data
, size_t size
)
1356 if (HDR_L2_WRITING(hdr
)) {
1357 l2arc_data_free_t
*df
;
1358 df
= kmem_alloc(sizeof (l2arc_data_free_t
), KM_SLEEP
);
1359 df
->l2df_data
= data
;
1360 df
->l2df_size
= size
;
1361 df
->l2df_func
= free_func
;
1362 mutex_enter(&l2arc_free_on_write_mtx
);
1363 list_insert_head(l2arc_free_on_write
, df
);
1364 mutex_exit(&l2arc_free_on_write_mtx
);
1365 ARCSTAT_BUMP(arcstat_l2_free_on_write
);
1367 free_func(data
, size
);
1372 arc_buf_destroy(arc_buf_t
*buf
, boolean_t recycle
, boolean_t all
)
1376 /* free up data associated with the buf */
1378 arc_state_t
*state
= buf
->b_hdr
->b_state
;
1379 uint64_t size
= buf
->b_hdr
->b_size
;
1380 arc_buf_contents_t type
= buf
->b_hdr
->b_type
;
1382 arc_cksum_verify(buf
);
1385 if (type
== ARC_BUFC_METADATA
) {
1386 arc_buf_data_free(buf
->b_hdr
, zio_buf_free
,
1388 arc_space_return(size
, ARC_SPACE_DATA
);
1390 ASSERT(type
== ARC_BUFC_DATA
);
1391 arc_buf_data_free(buf
->b_hdr
,
1392 zio_data_buf_free
, buf
->b_data
, size
);
1393 ARCSTAT_INCR(arcstat_data_size
, -size
);
1394 atomic_add_64(&arc_size
, -size
);
1397 if (list_link_active(&buf
->b_hdr
->b_arc_node
)) {
1398 uint64_t *cnt
= &state
->arcs_lsize
[type
];
1400 ASSERT(refcount_is_zero(&buf
->b_hdr
->b_refcnt
));
1401 ASSERT(state
!= arc_anon
);
1403 ASSERT3U(*cnt
, >=, size
);
1404 atomic_add_64(cnt
, -size
);
1406 ASSERT3U(state
->arcs_size
, >=, size
);
1407 atomic_add_64(&state
->arcs_size
, -size
);
1409 ASSERT(buf
->b_hdr
->b_datacnt
> 0);
1410 buf
->b_hdr
->b_datacnt
-= 1;
1413 /* only remove the buf if requested */
1417 /* remove the buf from the hdr list */
1418 for (bufp
= &buf
->b_hdr
->b_buf
; *bufp
!= buf
; bufp
= &(*bufp
)->b_next
)
1420 *bufp
= buf
->b_next
;
1423 ASSERT(buf
->b_efunc
== NULL
);
1425 /* clean up the buf */
1427 kmem_cache_free(buf_cache
, buf
);
1431 arc_hdr_destroy(arc_buf_hdr_t
*hdr
)
1433 l2arc_buf_hdr_t
*l2hdr
= hdr
->b_l2hdr
;
1435 ASSERT(refcount_is_zero(&hdr
->b_refcnt
));
1436 ASSERT3P(hdr
->b_state
, ==, arc_anon
);
1437 ASSERT(!HDR_IO_IN_PROGRESS(hdr
));
1439 if (l2hdr
!= NULL
) {
1440 boolean_t buflist_held
= MUTEX_HELD(&l2arc_buflist_mtx
);
1442 * To prevent arc_free() and l2arc_evict() from
1443 * attempting to free the same buffer at the same time,
1444 * a FREE_IN_PROGRESS flag is given to arc_free() to
1445 * give it priority. l2arc_evict() can't destroy this
1446 * header while we are waiting on l2arc_buflist_mtx.
1448 * The hdr may be removed from l2ad_buflist before we
1449 * grab l2arc_buflist_mtx, so b_l2hdr is rechecked.
1451 if (!buflist_held
) {
1452 mutex_enter(&l2arc_buflist_mtx
);
1453 l2hdr
= hdr
->b_l2hdr
;
1456 if (l2hdr
!= NULL
) {
1457 list_remove(l2hdr
->b_dev
->l2ad_buflist
, hdr
);
1458 ARCSTAT_INCR(arcstat_l2_size
, -hdr
->b_size
);
1459 kmem_free(l2hdr
, sizeof (l2arc_buf_hdr_t
));
1460 if (hdr
->b_state
== arc_l2c_only
)
1461 l2arc_hdr_stat_remove();
1462 hdr
->b_l2hdr
= NULL
;
1466 mutex_exit(&l2arc_buflist_mtx
);
1469 if (!BUF_EMPTY(hdr
)) {
1470 ASSERT(!HDR_IN_HASH_TABLE(hdr
));
1471 buf_discard_identity(hdr
);
1473 while (hdr
->b_buf
) {
1474 arc_buf_t
*buf
= hdr
->b_buf
;
1477 mutex_enter(&arc_eviction_mtx
);
1478 mutex_enter(&buf
->b_evict_lock
);
1479 ASSERT(buf
->b_hdr
!= NULL
);
1480 arc_buf_destroy(hdr
->b_buf
, FALSE
, FALSE
);
1481 hdr
->b_buf
= buf
->b_next
;
1482 buf
->b_hdr
= &arc_eviction_hdr
;
1483 buf
->b_next
= arc_eviction_list
;
1484 arc_eviction_list
= buf
;
1485 mutex_exit(&buf
->b_evict_lock
);
1486 mutex_exit(&arc_eviction_mtx
);
1488 arc_buf_destroy(hdr
->b_buf
, FALSE
, TRUE
);
1491 if (hdr
->b_freeze_cksum
!= NULL
) {
1492 kmem_free(hdr
->b_freeze_cksum
, sizeof (zio_cksum_t
));
1493 hdr
->b_freeze_cksum
= NULL
;
1495 if (hdr
->b_thawed
) {
1496 kmem_free(hdr
->b_thawed
, 1);
1497 hdr
->b_thawed
= NULL
;
1500 ASSERT(!list_link_active(&hdr
->b_arc_node
));
1501 ASSERT3P(hdr
->b_hash_next
, ==, NULL
);
1502 ASSERT3P(hdr
->b_acb
, ==, NULL
);
1503 kmem_cache_free(hdr_cache
, hdr
);
1507 arc_buf_free(arc_buf_t
*buf
, void *tag
)
1509 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
1510 int hashed
= hdr
->b_state
!= arc_anon
;
1512 ASSERT(buf
->b_efunc
== NULL
);
1513 ASSERT(buf
->b_data
!= NULL
);
1516 kmutex_t
*hash_lock
= HDR_LOCK(hdr
);
1518 mutex_enter(hash_lock
);
1520 ASSERT3P(hash_lock
, ==, HDR_LOCK(hdr
));
1522 (void) remove_reference(hdr
, hash_lock
, tag
);
1523 if (hdr
->b_datacnt
> 1) {
1524 arc_buf_destroy(buf
, FALSE
, TRUE
);
1526 ASSERT(buf
== hdr
->b_buf
);
1527 ASSERT(buf
->b_efunc
== NULL
);
1528 hdr
->b_flags
|= ARC_BUF_AVAILABLE
;
1530 mutex_exit(hash_lock
);
1531 } else if (HDR_IO_IN_PROGRESS(hdr
)) {
1534 * We are in the middle of an async write. Don't destroy
1535 * this buffer unless the write completes before we finish
1536 * decrementing the reference count.
1538 mutex_enter(&arc_eviction_mtx
);
1539 (void) remove_reference(hdr
, NULL
, tag
);
1540 ASSERT(refcount_is_zero(&hdr
->b_refcnt
));
1541 destroy_hdr
= !HDR_IO_IN_PROGRESS(hdr
);
1542 mutex_exit(&arc_eviction_mtx
);
1544 arc_hdr_destroy(hdr
);
1546 if (remove_reference(hdr
, NULL
, tag
) > 0)
1547 arc_buf_destroy(buf
, FALSE
, TRUE
);
1549 arc_hdr_destroy(hdr
);
1554 arc_buf_remove_ref(arc_buf_t
*buf
, void* tag
)
1556 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
1557 kmutex_t
*hash_lock
= HDR_LOCK(hdr
);
1558 int no_callback
= (buf
->b_efunc
== NULL
);
1560 if (hdr
->b_state
== arc_anon
) {
1561 ASSERT(hdr
->b_datacnt
== 1);
1562 arc_buf_free(buf
, tag
);
1563 return (no_callback
);
1566 mutex_enter(hash_lock
);
1568 ASSERT3P(hash_lock
, ==, HDR_LOCK(hdr
));
1569 ASSERT(hdr
->b_state
!= arc_anon
);
1570 ASSERT(buf
->b_data
!= NULL
);
1572 (void) remove_reference(hdr
, hash_lock
, tag
);
1573 if (hdr
->b_datacnt
> 1) {
1575 arc_buf_destroy(buf
, FALSE
, TRUE
);
1576 } else if (no_callback
) {
1577 ASSERT(hdr
->b_buf
== buf
&& buf
->b_next
== NULL
);
1578 ASSERT(buf
->b_efunc
== NULL
);
1579 hdr
->b_flags
|= ARC_BUF_AVAILABLE
;
1581 ASSERT(no_callback
|| hdr
->b_datacnt
> 1 ||
1582 refcount_is_zero(&hdr
->b_refcnt
));
1583 mutex_exit(hash_lock
);
1584 return (no_callback
);
1588 arc_buf_size(arc_buf_t
*buf
)
1590 return (buf
->b_hdr
->b_size
);
1594 * Evict buffers from list until we've removed the specified number of
1595 * bytes. Move the removed buffers to the appropriate evict state.
1596 * If the recycle flag is set, then attempt to "recycle" a buffer:
1597 * - look for a buffer to evict that is `bytes' long.
1598 * - return the data block from this buffer rather than freeing it.
1599 * This flag is used by callers that are trying to make space for a
1600 * new buffer in a full arc cache.
1602 * This function makes a "best effort". It skips over any buffers
1603 * it can't get a hash_lock on, and so may not catch all candidates.
1604 * It may also return without evicting as much space as requested.
1607 arc_evict(arc_state_t
*state
, uint64_t spa
, int64_t bytes
, boolean_t recycle
,
1608 arc_buf_contents_t type
)
1610 arc_state_t
*evicted_state
;
1611 uint64_t bytes_evicted
= 0, skipped
= 0, missed
= 0;
1612 arc_buf_hdr_t
*ab
, *ab_prev
= NULL
;
1613 list_t
*list
= &state
->arcs_list
[type
];
1614 kmutex_t
*hash_lock
;
1615 boolean_t have_lock
;
1616 void *stolen
= NULL
;
1618 ASSERT(state
== arc_mru
|| state
== arc_mfu
);
1620 evicted_state
= (state
== arc_mru
) ? arc_mru_ghost
: arc_mfu_ghost
;
1622 mutex_enter(&state
->arcs_mtx
);
1623 mutex_enter(&evicted_state
->arcs_mtx
);
1625 for (ab
= list_tail(list
); ab
; ab
= ab_prev
) {
1626 ab_prev
= list_prev(list
, ab
);
1627 /* prefetch buffers have a minimum lifespan */
1628 if (HDR_IO_IN_PROGRESS(ab
) ||
1629 (spa
&& ab
->b_spa
!= spa
) ||
1630 (ab
->b_flags
& (ARC_PREFETCH
|ARC_INDIRECT
) &&
1631 ddi_get_lbolt() - ab
->b_arc_access
<
1632 arc_min_prefetch_lifespan
)) {
1636 /* "lookahead" for better eviction candidate */
1637 if (recycle
&& ab
->b_size
!= bytes
&&
1638 ab_prev
&& ab_prev
->b_size
== bytes
)
1640 hash_lock
= HDR_LOCK(ab
);
1641 have_lock
= MUTEX_HELD(hash_lock
);
1642 if (have_lock
|| mutex_tryenter(hash_lock
)) {
1643 ASSERT3U(refcount_count(&ab
->b_refcnt
), ==, 0);
1644 ASSERT(ab
->b_datacnt
> 0);
1646 arc_buf_t
*buf
= ab
->b_buf
;
1647 if (!mutex_tryenter(&buf
->b_evict_lock
)) {
1652 bytes_evicted
+= ab
->b_size
;
1653 if (recycle
&& ab
->b_type
== type
&&
1654 ab
->b_size
== bytes
&&
1655 !HDR_L2_WRITING(ab
)) {
1656 stolen
= buf
->b_data
;
1661 mutex_enter(&arc_eviction_mtx
);
1662 arc_buf_destroy(buf
,
1663 buf
->b_data
== stolen
, FALSE
);
1664 ab
->b_buf
= buf
->b_next
;
1665 buf
->b_hdr
= &arc_eviction_hdr
;
1666 buf
->b_next
= arc_eviction_list
;
1667 arc_eviction_list
= buf
;
1668 mutex_exit(&arc_eviction_mtx
);
1669 mutex_exit(&buf
->b_evict_lock
);
1671 mutex_exit(&buf
->b_evict_lock
);
1672 arc_buf_destroy(buf
,
1673 buf
->b_data
== stolen
, TRUE
);
1678 ARCSTAT_INCR(arcstat_evict_l2_cached
,
1681 if (l2arc_write_eligible(ab
->b_spa
, ab
)) {
1682 ARCSTAT_INCR(arcstat_evict_l2_eligible
,
1686 arcstat_evict_l2_ineligible
,
1691 if (ab
->b_datacnt
== 0) {
1692 arc_change_state(evicted_state
, ab
, hash_lock
);
1693 ASSERT(HDR_IN_HASH_TABLE(ab
));
1694 ab
->b_flags
|= ARC_IN_HASH_TABLE
;
1695 ab
->b_flags
&= ~ARC_BUF_AVAILABLE
;
1696 DTRACE_PROBE1(arc__evict
, arc_buf_hdr_t
*, ab
);
1699 mutex_exit(hash_lock
);
1700 if (bytes
>= 0 && bytes_evicted
>= bytes
)
1707 mutex_exit(&evicted_state
->arcs_mtx
);
1708 mutex_exit(&state
->arcs_mtx
);
1710 if (bytes_evicted
< bytes
)
1711 dprintf("only evicted %lld bytes from %x",
1712 (longlong_t
)bytes_evicted
, state
);
1715 ARCSTAT_INCR(arcstat_evict_skip
, skipped
);
1718 ARCSTAT_INCR(arcstat_mutex_miss
, missed
);
1721 * We have just evicted some date into the ghost state, make
1722 * sure we also adjust the ghost state size if necessary.
1725 arc_mru_ghost
->arcs_size
+ arc_mfu_ghost
->arcs_size
> arc_c
) {
1726 int64_t mru_over
= arc_anon
->arcs_size
+ arc_mru
->arcs_size
+
1727 arc_mru_ghost
->arcs_size
- arc_c
;
1729 if (mru_over
> 0 && arc_mru_ghost
->arcs_lsize
[type
] > 0) {
1731 MIN(arc_mru_ghost
->arcs_lsize
[type
], mru_over
);
1732 arc_evict_ghost(arc_mru_ghost
, 0, todelete
);
1733 } else if (arc_mfu_ghost
->arcs_lsize
[type
] > 0) {
1734 int64_t todelete
= MIN(arc_mfu_ghost
->arcs_lsize
[type
],
1735 arc_mru_ghost
->arcs_size
+
1736 arc_mfu_ghost
->arcs_size
- arc_c
);
1737 arc_evict_ghost(arc_mfu_ghost
, 0, todelete
);
1745 * Remove buffers from list until we've removed the specified number of
1746 * bytes. Destroy the buffers that are removed.
1749 arc_evict_ghost(arc_state_t
*state
, uint64_t spa
, int64_t bytes
)
1751 arc_buf_hdr_t
*ab
, *ab_prev
;
1752 arc_buf_hdr_t marker
;
1753 list_t
*list
= &state
->arcs_list
[ARC_BUFC_DATA
];
1754 kmutex_t
*hash_lock
;
1755 uint64_t bytes_deleted
= 0;
1756 uint64_t bufs_skipped
= 0;
1758 ASSERT(GHOST_STATE(state
));
1759 bzero(&marker
, sizeof(marker
));
1761 mutex_enter(&state
->arcs_mtx
);
1762 for (ab
= list_tail(list
); ab
; ab
= ab_prev
) {
1763 ab_prev
= list_prev(list
, ab
);
1764 if (spa
&& ab
->b_spa
!= spa
)
1767 /* ignore markers */
1771 hash_lock
= HDR_LOCK(ab
);
1772 /* caller may be trying to modify this buffer, skip it */
1773 if (MUTEX_HELD(hash_lock
))
1775 if (mutex_tryenter(hash_lock
)) {
1776 ASSERT(!HDR_IO_IN_PROGRESS(ab
));
1777 ASSERT(ab
->b_buf
== NULL
);
1778 ARCSTAT_BUMP(arcstat_deleted
);
1779 bytes_deleted
+= ab
->b_size
;
1781 if (ab
->b_l2hdr
!= NULL
) {
1783 * This buffer is cached on the 2nd Level ARC;
1784 * don't destroy the header.
1786 arc_change_state(arc_l2c_only
, ab
, hash_lock
);
1787 mutex_exit(hash_lock
);
1789 arc_change_state(arc_anon
, ab
, hash_lock
);
1790 mutex_exit(hash_lock
);
1791 arc_hdr_destroy(ab
);
1794 DTRACE_PROBE1(arc__delete
, arc_buf_hdr_t
*, ab
);
1795 if (bytes
>= 0 && bytes_deleted
>= bytes
)
1797 } else if (bytes
< 0) {
1799 * Insert a list marker and then wait for the
1800 * hash lock to become available. Once its
1801 * available, restart from where we left off.
1803 list_insert_after(list
, ab
, &marker
);
1804 mutex_exit(&state
->arcs_mtx
);
1805 mutex_enter(hash_lock
);
1806 mutex_exit(hash_lock
);
1807 mutex_enter(&state
->arcs_mtx
);
1808 ab_prev
= list_prev(list
, &marker
);
1809 list_remove(list
, &marker
);
1813 mutex_exit(&state
->arcs_mtx
);
1815 if (list
== &state
->arcs_list
[ARC_BUFC_DATA
] &&
1816 (bytes
< 0 || bytes_deleted
< bytes
)) {
1817 list
= &state
->arcs_list
[ARC_BUFC_METADATA
];
1822 ARCSTAT_INCR(arcstat_mutex_miss
, bufs_skipped
);
1826 if (bytes_deleted
< bytes
)
1827 dprintf("only deleted %lld bytes from %p",
1828 (longlong_t
)bytes_deleted
, state
);
1834 int64_t adjustment
, delta
;
1840 adjustment
= MIN((int64_t)(arc_size
- arc_c
),
1841 (int64_t)(arc_anon
->arcs_size
+ arc_mru
->arcs_size
+ arc_meta_used
-
1844 if (adjustment
> 0 && arc_mru
->arcs_lsize
[ARC_BUFC_DATA
] > 0) {
1845 delta
= MIN(arc_mru
->arcs_lsize
[ARC_BUFC_DATA
], adjustment
);
1846 (void) arc_evict(arc_mru
, 0, delta
, FALSE
, ARC_BUFC_DATA
);
1847 adjustment
-= delta
;
1850 if (adjustment
> 0 && arc_mru
->arcs_lsize
[ARC_BUFC_METADATA
] > 0) {
1851 delta
= MIN(arc_mru
->arcs_lsize
[ARC_BUFC_METADATA
], adjustment
);
1852 (void) arc_evict(arc_mru
, 0, delta
, FALSE
,
1860 adjustment
= arc_size
- arc_c
;
1862 if (adjustment
> 0 && arc_mfu
->arcs_lsize
[ARC_BUFC_DATA
] > 0) {
1863 delta
= MIN(adjustment
, arc_mfu
->arcs_lsize
[ARC_BUFC_DATA
]);
1864 (void) arc_evict(arc_mfu
, 0, delta
, FALSE
, ARC_BUFC_DATA
);
1865 adjustment
-= delta
;
1868 if (adjustment
> 0 && arc_mfu
->arcs_lsize
[ARC_BUFC_METADATA
] > 0) {
1869 int64_t delta
= MIN(adjustment
,
1870 arc_mfu
->arcs_lsize
[ARC_BUFC_METADATA
]);
1871 (void) arc_evict(arc_mfu
, 0, delta
, FALSE
,
1876 * Adjust ghost lists
1879 adjustment
= arc_mru
->arcs_size
+ arc_mru_ghost
->arcs_size
- arc_c
;
1881 if (adjustment
> 0 && arc_mru_ghost
->arcs_size
> 0) {
1882 delta
= MIN(arc_mru_ghost
->arcs_size
, adjustment
);
1883 arc_evict_ghost(arc_mru_ghost
, 0, delta
);
1887 arc_mru_ghost
->arcs_size
+ arc_mfu_ghost
->arcs_size
- arc_c
;
1889 if (adjustment
> 0 && arc_mfu_ghost
->arcs_size
> 0) {
1890 delta
= MIN(arc_mfu_ghost
->arcs_size
, adjustment
);
1891 arc_evict_ghost(arc_mfu_ghost
, 0, delta
);
1896 arc_do_user_evicts(void)
1898 mutex_enter(&arc_eviction_mtx
);
1899 while (arc_eviction_list
!= NULL
) {
1900 arc_buf_t
*buf
= arc_eviction_list
;
1901 arc_eviction_list
= buf
->b_next
;
1902 mutex_enter(&buf
->b_evict_lock
);
1904 mutex_exit(&buf
->b_evict_lock
);
1905 mutex_exit(&arc_eviction_mtx
);
1907 if (buf
->b_efunc
!= NULL
)
1908 VERIFY(buf
->b_efunc(buf
) == 0);
1910 buf
->b_efunc
= NULL
;
1911 buf
->b_private
= NULL
;
1912 kmem_cache_free(buf_cache
, buf
);
1913 mutex_enter(&arc_eviction_mtx
);
1915 mutex_exit(&arc_eviction_mtx
);
1919 * Flush all *evictable* data from the cache for the given spa.
1920 * NOTE: this will not touch "active" (i.e. referenced) data.
1923 arc_flush(spa_t
*spa
)
1928 guid
= spa_guid(spa
);
1930 while (list_head(&arc_mru
->arcs_list
[ARC_BUFC_DATA
])) {
1931 (void) arc_evict(arc_mru
, guid
, -1, FALSE
, ARC_BUFC_DATA
);
1935 while (list_head(&arc_mru
->arcs_list
[ARC_BUFC_METADATA
])) {
1936 (void) arc_evict(arc_mru
, guid
, -1, FALSE
, ARC_BUFC_METADATA
);
1940 while (list_head(&arc_mfu
->arcs_list
[ARC_BUFC_DATA
])) {
1941 (void) arc_evict(arc_mfu
, guid
, -1, FALSE
, ARC_BUFC_DATA
);
1945 while (list_head(&arc_mfu
->arcs_list
[ARC_BUFC_METADATA
])) {
1946 (void) arc_evict(arc_mfu
, guid
, -1, FALSE
, ARC_BUFC_METADATA
);
1951 arc_evict_ghost(arc_mru_ghost
, guid
, -1);
1952 arc_evict_ghost(arc_mfu_ghost
, guid
, -1);
1954 mutex_enter(&arc_reclaim_thr_lock
);
1955 arc_do_user_evicts();
1956 mutex_exit(&arc_reclaim_thr_lock
);
1957 ASSERT(spa
|| arc_eviction_list
== NULL
);
1963 if (arc_c
> arc_c_min
) {
1967 to_free
= MAX(arc_c
>> arc_shrink_shift
, ptob(needfree
));
1969 to_free
= arc_c
>> arc_shrink_shift
;
1971 if (arc_c
> arc_c_min
+ to_free
)
1972 atomic_add_64(&arc_c
, -to_free
);
1976 atomic_add_64(&arc_p
, -(arc_p
>> arc_shrink_shift
));
1977 if (arc_c
> arc_size
)
1978 arc_c
= MAX(arc_size
, arc_c_min
);
1980 arc_p
= (arc_c
>> 1);
1981 ASSERT(arc_c
>= arc_c_min
);
1982 ASSERT((int64_t)arc_p
>= 0);
1985 if (arc_size
> arc_c
)
1990 arc_reclaim_needed(void)
1999 * take 'desfree' extra pages, so we reclaim sooner, rather than later
2004 * check that we're out of range of the pageout scanner. It starts to
2005 * schedule paging if freemem is less than lotsfree and needfree.
2006 * lotsfree is the high-water mark for pageout, and needfree is the
2007 * number of needed free pages. We add extra pages here to make sure
2008 * the scanner doesn't start up while we're freeing memory.
2010 if (freemem
< lotsfree
+ needfree
+ extra
)
2014 * check to make sure that swapfs has enough space so that anon
2015 * reservations can still succeed. anon_resvmem() checks that the
2016 * availrmem is greater than swapfs_minfree, and the number of reserved
2017 * swap pages. We also add a bit of extra here just to prevent
2018 * circumstances from getting really dire.
2020 if (availrmem
< swapfs_minfree
+ swapfs_reserve
+ extra
)
2025 * If we're on an i386 platform, it's possible that we'll exhaust the
2026 * kernel heap space before we ever run out of available physical
2027 * memory. Most checks of the size of the heap_area compare against
2028 * tune.t_minarmem, which is the minimum available real memory that we
2029 * can have in the system. However, this is generally fixed at 25 pages
2030 * which is so low that it's useless. In this comparison, we seek to
2031 * calculate the total heap-size, and reclaim if more than 3/4ths of the
2032 * heap is allocated. (Or, in the calculation, if less than 1/4th is
2035 if (btop(vmem_size(heap_arena
, VMEM_FREE
)) <
2036 (btop(vmem_size(heap_arena
, VMEM_FREE
| VMEM_ALLOC
)) >> 2))
2041 if (spa_get_random(100) == 0)
2048 arc_kmem_reap_now(arc_reclaim_strategy_t strat
)
2051 kmem_cache_t
*prev_cache
= NULL
;
2052 kmem_cache_t
*prev_data_cache
= NULL
;
2053 extern kmem_cache_t
*zio_buf_cache
[];
2054 extern kmem_cache_t
*zio_data_buf_cache
[];
2057 if (arc_meta_used
>= arc_meta_limit
) {
2059 * We are exceeding our meta-data cache limit.
2060 * Purge some DNLC entries to release holds on meta-data.
2062 dnlc_reduce_cache((void *)(uintptr_t)arc_reduce_dnlc_percent
);
2066 * Reclaim unused memory from all kmem caches.
2073 * An aggressive reclamation will shrink the cache size as well as
2074 * reap free buffers from the arc kmem caches.
2076 if (strat
== ARC_RECLAIM_AGGR
)
2079 for (i
= 0; i
< SPA_MAXBLOCKSIZE
>> SPA_MINBLOCKSHIFT
; i
++) {
2080 if (zio_buf_cache
[i
] != prev_cache
) {
2081 prev_cache
= zio_buf_cache
[i
];
2082 kmem_cache_reap_now(zio_buf_cache
[i
]);
2084 if (zio_data_buf_cache
[i
] != prev_data_cache
) {
2085 prev_data_cache
= zio_data_buf_cache
[i
];
2086 kmem_cache_reap_now(zio_data_buf_cache
[i
]);
2089 kmem_cache_reap_now(buf_cache
);
2090 kmem_cache_reap_now(hdr_cache
);
2094 arc_reclaim_thread(void)
2096 clock_t growtime
= 0;
2097 arc_reclaim_strategy_t last_reclaim
= ARC_RECLAIM_CONS
;
2100 CALLB_CPR_INIT(&cpr
, &arc_reclaim_thr_lock
, callb_generic_cpr
, FTAG
);
2102 mutex_enter(&arc_reclaim_thr_lock
);
2103 while (arc_thread_exit
== 0) {
2104 if (arc_reclaim_needed()) {
2107 if (last_reclaim
== ARC_RECLAIM_CONS
) {
2108 last_reclaim
= ARC_RECLAIM_AGGR
;
2110 last_reclaim
= ARC_RECLAIM_CONS
;
2114 last_reclaim
= ARC_RECLAIM_AGGR
;
2118 /* reset the growth delay for every reclaim */
2119 growtime
= ddi_get_lbolt() + (arc_grow_retry
* hz
);
2121 arc_kmem_reap_now(last_reclaim
);
2124 } else if (arc_no_grow
&& ddi_get_lbolt() >= growtime
) {
2125 arc_no_grow
= FALSE
;
2130 if (arc_eviction_list
!= NULL
)
2131 arc_do_user_evicts();
2133 /* block until needed, or one second, whichever is shorter */
2134 CALLB_CPR_SAFE_BEGIN(&cpr
);
2135 (void) cv_timedwait(&arc_reclaim_thr_cv
,
2136 &arc_reclaim_thr_lock
, (ddi_get_lbolt() + hz
));
2137 CALLB_CPR_SAFE_END(&cpr
, &arc_reclaim_thr_lock
);
2140 arc_thread_exit
= 0;
2141 cv_broadcast(&arc_reclaim_thr_cv
);
2142 CALLB_CPR_EXIT(&cpr
); /* drops arc_reclaim_thr_lock */
2147 * Adapt arc info given the number of bytes we are trying to add and
2148 * the state that we are comming from. This function is only called
2149 * when we are adding new content to the cache.
2152 arc_adapt(int bytes
, arc_state_t
*state
)
2155 uint64_t arc_p_min
= (arc_c
>> arc_p_min_shift
);
2157 if (state
== arc_l2c_only
)
2162 * Adapt the target size of the MRU list:
2163 * - if we just hit in the MRU ghost list, then increase
2164 * the target size of the MRU list.
2165 * - if we just hit in the MFU ghost list, then increase
2166 * the target size of the MFU list by decreasing the
2167 * target size of the MRU list.
2169 if (state
== arc_mru_ghost
) {
2170 mult
= ((arc_mru_ghost
->arcs_size
>= arc_mfu_ghost
->arcs_size
) ?
2171 1 : (arc_mfu_ghost
->arcs_size
/arc_mru_ghost
->arcs_size
));
2172 mult
= MIN(mult
, 10); /* avoid wild arc_p adjustment */
2174 arc_p
= MIN(arc_c
- arc_p_min
, arc_p
+ bytes
* mult
);
2175 } else if (state
== arc_mfu_ghost
) {
2178 mult
= ((arc_mfu_ghost
->arcs_size
>= arc_mru_ghost
->arcs_size
) ?
2179 1 : (arc_mru_ghost
->arcs_size
/arc_mfu_ghost
->arcs_size
));
2180 mult
= MIN(mult
, 10);
2182 delta
= MIN(bytes
* mult
, arc_p
);
2183 arc_p
= MAX(arc_p_min
, arc_p
- delta
);
2185 ASSERT((int64_t)arc_p
>= 0);
2187 if (arc_reclaim_needed()) {
2188 cv_signal(&arc_reclaim_thr_cv
);
2195 if (arc_c
>= arc_c_max
)
2199 * If we're within (2 * maxblocksize) bytes of the target
2200 * cache size, increment the target cache size
2202 if (arc_size
> arc_c
- (2ULL << SPA_MAXBLOCKSHIFT
)) {
2203 atomic_add_64(&arc_c
, (int64_t)bytes
);
2204 if (arc_c
> arc_c_max
)
2206 else if (state
== arc_anon
)
2207 atomic_add_64(&arc_p
, (int64_t)bytes
);
2211 ASSERT((int64_t)arc_p
>= 0);
2215 * Check if the cache has reached its limits and eviction is required
2219 arc_evict_needed(arc_buf_contents_t type
)
2221 if (type
== ARC_BUFC_METADATA
&& arc_meta_used
>= arc_meta_limit
)
2226 * If zio data pages are being allocated out of a separate heap segment,
2227 * then enforce that the size of available vmem for this area remains
2228 * above about 1/32nd free.
2230 if (type
== ARC_BUFC_DATA
&& zio_arena
!= NULL
&&
2231 vmem_size(zio_arena
, VMEM_FREE
) <
2232 (vmem_size(zio_arena
, VMEM_ALLOC
) >> 5))
2236 if (arc_reclaim_needed())
2239 return (arc_size
> arc_c
);
2243 * The buffer, supplied as the first argument, needs a data block.
2244 * So, if we are at cache max, determine which cache should be victimized.
2245 * We have the following cases:
2247 * 1. Insert for MRU, p > sizeof(arc_anon + arc_mru) ->
2248 * In this situation if we're out of space, but the resident size of the MFU is
2249 * under the limit, victimize the MFU cache to satisfy this insertion request.
2251 * 2. Insert for MRU, p <= sizeof(arc_anon + arc_mru) ->
2252 * Here, we've used up all of the available space for the MRU, so we need to
2253 * evict from our own cache instead. Evict from the set of resident MRU
2256 * 3. Insert for MFU (c - p) > sizeof(arc_mfu) ->
2257 * c minus p represents the MFU space in the cache, since p is the size of the
2258 * cache that is dedicated to the MRU. In this situation there's still space on
2259 * the MFU side, so the MRU side needs to be victimized.
2261 * 4. Insert for MFU (c - p) < sizeof(arc_mfu) ->
2262 * MFU's resident set is consuming more space than it has been allotted. In
2263 * this situation, we must victimize our own cache, the MFU, for this insertion.
2266 arc_get_data_buf(arc_buf_t
*buf
)
2268 arc_state_t
*state
= buf
->b_hdr
->b_state
;
2269 uint64_t size
= buf
->b_hdr
->b_size
;
2270 arc_buf_contents_t type
= buf
->b_hdr
->b_type
;
2272 arc_adapt(size
, state
);
2275 * We have not yet reached cache maximum size,
2276 * just allocate a new buffer.
2278 if (!arc_evict_needed(type
)) {
2279 if (type
== ARC_BUFC_METADATA
) {
2280 buf
->b_data
= zio_buf_alloc(size
);
2281 arc_space_consume(size
, ARC_SPACE_DATA
);
2283 ASSERT(type
== ARC_BUFC_DATA
);
2284 buf
->b_data
= zio_data_buf_alloc(size
);
2285 ARCSTAT_INCR(arcstat_data_size
, size
);
2286 atomic_add_64(&arc_size
, size
);
2292 * If we are prefetching from the mfu ghost list, this buffer
2293 * will end up on the mru list; so steal space from there.
2295 if (state
== arc_mfu_ghost
)
2296 state
= buf
->b_hdr
->b_flags
& ARC_PREFETCH
? arc_mru
: arc_mfu
;
2297 else if (state
== arc_mru_ghost
)
2300 if (state
== arc_mru
|| state
== arc_anon
) {
2301 uint64_t mru_used
= arc_anon
->arcs_size
+ arc_mru
->arcs_size
;
2302 state
= (arc_mfu
->arcs_lsize
[type
] >= size
&&
2303 arc_p
> mru_used
) ? arc_mfu
: arc_mru
;
2306 uint64_t mfu_space
= arc_c
- arc_p
;
2307 state
= (arc_mru
->arcs_lsize
[type
] >= size
&&
2308 mfu_space
> arc_mfu
->arcs_size
) ? arc_mru
: arc_mfu
;
2310 if ((buf
->b_data
= arc_evict(state
, 0, size
, TRUE
, type
)) == NULL
) {
2311 if (type
== ARC_BUFC_METADATA
) {
2312 buf
->b_data
= zio_buf_alloc(size
);
2313 arc_space_consume(size
, ARC_SPACE_DATA
);
2315 ASSERT(type
== ARC_BUFC_DATA
);
2316 buf
->b_data
= zio_data_buf_alloc(size
);
2317 ARCSTAT_INCR(arcstat_data_size
, size
);
2318 atomic_add_64(&arc_size
, size
);
2320 ARCSTAT_BUMP(arcstat_recycle_miss
);
2322 ASSERT(buf
->b_data
!= NULL
);
2325 * Update the state size. Note that ghost states have a
2326 * "ghost size" and so don't need to be updated.
2328 if (!GHOST_STATE(buf
->b_hdr
->b_state
)) {
2329 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
2331 atomic_add_64(&hdr
->b_state
->arcs_size
, size
);
2332 if (list_link_active(&hdr
->b_arc_node
)) {
2333 ASSERT(refcount_is_zero(&hdr
->b_refcnt
));
2334 atomic_add_64(&hdr
->b_state
->arcs_lsize
[type
], size
);
2337 * If we are growing the cache, and we are adding anonymous
2338 * data, and we have outgrown arc_p, update arc_p
2340 if (arc_size
< arc_c
&& hdr
->b_state
== arc_anon
&&
2341 arc_anon
->arcs_size
+ arc_mru
->arcs_size
> arc_p
)
2342 arc_p
= MIN(arc_c
, arc_p
+ size
);
2347 * This routine is called whenever a buffer is accessed.
2348 * NOTE: the hash lock is dropped in this function.
2351 arc_access(arc_buf_hdr_t
*buf
, kmutex_t
*hash_lock
)
2355 ASSERT(MUTEX_HELD(hash_lock
));
2357 if (buf
->b_state
== arc_anon
) {
2359 * This buffer is not in the cache, and does not
2360 * appear in our "ghost" list. Add the new buffer
2364 ASSERT(buf
->b_arc_access
== 0);
2365 buf
->b_arc_access
= ddi_get_lbolt();
2366 DTRACE_PROBE1(new_state__mru
, arc_buf_hdr_t
*, buf
);
2367 arc_change_state(arc_mru
, buf
, hash_lock
);
2369 } else if (buf
->b_state
== arc_mru
) {
2370 now
= ddi_get_lbolt();
2373 * If this buffer is here because of a prefetch, then either:
2374 * - clear the flag if this is a "referencing" read
2375 * (any subsequent access will bump this into the MFU state).
2377 * - move the buffer to the head of the list if this is
2378 * another prefetch (to make it less likely to be evicted).
2380 if ((buf
->b_flags
& ARC_PREFETCH
) != 0) {
2381 if (refcount_count(&buf
->b_refcnt
) == 0) {
2382 ASSERT(list_link_active(&buf
->b_arc_node
));
2384 buf
->b_flags
&= ~ARC_PREFETCH
;
2385 ARCSTAT_BUMP(arcstat_mru_hits
);
2387 buf
->b_arc_access
= now
;
2392 * This buffer has been "accessed" only once so far,
2393 * but it is still in the cache. Move it to the MFU
2396 if (now
> buf
->b_arc_access
+ ARC_MINTIME
) {
2398 * More than 125ms have passed since we
2399 * instantiated this buffer. Move it to the
2400 * most frequently used state.
2402 buf
->b_arc_access
= now
;
2403 DTRACE_PROBE1(new_state__mfu
, arc_buf_hdr_t
*, buf
);
2404 arc_change_state(arc_mfu
, buf
, hash_lock
);
2406 ARCSTAT_BUMP(arcstat_mru_hits
);
2407 } else if (buf
->b_state
== arc_mru_ghost
) {
2408 arc_state_t
*new_state
;
2410 * This buffer has been "accessed" recently, but
2411 * was evicted from the cache. Move it to the
2415 if (buf
->b_flags
& ARC_PREFETCH
) {
2416 new_state
= arc_mru
;
2417 if (refcount_count(&buf
->b_refcnt
) > 0)
2418 buf
->b_flags
&= ~ARC_PREFETCH
;
2419 DTRACE_PROBE1(new_state__mru
, arc_buf_hdr_t
*, buf
);
2421 new_state
= arc_mfu
;
2422 DTRACE_PROBE1(new_state__mfu
, arc_buf_hdr_t
*, buf
);
2425 buf
->b_arc_access
= ddi_get_lbolt();
2426 arc_change_state(new_state
, buf
, hash_lock
);
2428 ARCSTAT_BUMP(arcstat_mru_ghost_hits
);
2429 } else if (buf
->b_state
== arc_mfu
) {
2431 * This buffer has been accessed more than once and is
2432 * still in the cache. Keep it in the MFU state.
2434 * NOTE: an add_reference() that occurred when we did
2435 * the arc_read() will have kicked this off the list.
2436 * If it was a prefetch, we will explicitly move it to
2437 * the head of the list now.
2439 if ((buf
->b_flags
& ARC_PREFETCH
) != 0) {
2440 ASSERT(refcount_count(&buf
->b_refcnt
) == 0);
2441 ASSERT(list_link_active(&buf
->b_arc_node
));
2443 ARCSTAT_BUMP(arcstat_mfu_hits
);
2444 buf
->b_arc_access
= ddi_get_lbolt();
2445 } else if (buf
->b_state
== arc_mfu_ghost
) {
2446 arc_state_t
*new_state
= arc_mfu
;
2448 * This buffer has been accessed more than once but has
2449 * been evicted from the cache. Move it back to the
2453 if (buf
->b_flags
& ARC_PREFETCH
) {
2455 * This is a prefetch access...
2456 * move this block back to the MRU state.
2458 ASSERT3U(refcount_count(&buf
->b_refcnt
), ==, 0);
2459 new_state
= arc_mru
;
2462 buf
->b_arc_access
= ddi_get_lbolt();
2463 DTRACE_PROBE1(new_state__mfu
, arc_buf_hdr_t
*, buf
);
2464 arc_change_state(new_state
, buf
, hash_lock
);
2466 ARCSTAT_BUMP(arcstat_mfu_ghost_hits
);
2467 } else if (buf
->b_state
== arc_l2c_only
) {
2469 * This buffer is on the 2nd Level ARC.
2472 buf
->b_arc_access
= ddi_get_lbolt();
2473 DTRACE_PROBE1(new_state__mfu
, arc_buf_hdr_t
*, buf
);
2474 arc_change_state(arc_mfu
, buf
, hash_lock
);
2476 ASSERT(!"invalid arc state");
2480 /* a generic arc_done_func_t which you can use */
2483 arc_bcopy_func(zio_t
*zio
, arc_buf_t
*buf
, void *arg
)
2485 if (zio
== NULL
|| zio
->io_error
== 0)
2486 bcopy(buf
->b_data
, arg
, buf
->b_hdr
->b_size
);
2487 VERIFY(arc_buf_remove_ref(buf
, arg
) == 1);
2490 /* a generic arc_done_func_t */
2492 arc_getbuf_func(zio_t
*zio
, arc_buf_t
*buf
, void *arg
)
2494 arc_buf_t
**bufp
= arg
;
2495 if (zio
&& zio
->io_error
) {
2496 VERIFY(arc_buf_remove_ref(buf
, arg
) == 1);
2500 ASSERT(buf
->b_data
);
2505 arc_read_done(zio_t
*zio
)
2507 arc_buf_hdr_t
*hdr
, *found
;
2509 arc_buf_t
*abuf
; /* buffer we're assigning to callback */
2510 kmutex_t
*hash_lock
;
2511 arc_callback_t
*callback_list
, *acb
;
2512 int freeable
= FALSE
;
2514 buf
= zio
->io_private
;
2518 * The hdr was inserted into hash-table and removed from lists
2519 * prior to starting I/O. We should find this header, since
2520 * it's in the hash table, and it should be legit since it's
2521 * not possible to evict it during the I/O. The only possible
2522 * reason for it not to be found is if we were freed during the
2525 found
= buf_hash_find(hdr
->b_spa
, &hdr
->b_dva
, hdr
->b_birth
,
2528 ASSERT((found
== NULL
&& HDR_FREED_IN_READ(hdr
) && hash_lock
== NULL
) ||
2529 (found
== hdr
&& DVA_EQUAL(&hdr
->b_dva
, BP_IDENTITY(zio
->io_bp
))) ||
2530 (found
== hdr
&& HDR_L2_READING(hdr
)));
2532 hdr
->b_flags
&= ~ARC_L2_EVICTED
;
2533 if (l2arc_noprefetch
&& (hdr
->b_flags
& ARC_PREFETCH
))
2534 hdr
->b_flags
&= ~ARC_L2CACHE
;
2536 /* byteswap if necessary */
2537 callback_list
= hdr
->b_acb
;
2538 ASSERT(callback_list
!= NULL
);
2539 if (BP_SHOULD_BYTESWAP(zio
->io_bp
) && zio
->io_error
== 0) {
2540 arc_byteswap_func_t
*func
= BP_GET_LEVEL(zio
->io_bp
) > 0 ?
2541 byteswap_uint64_array
:
2542 dmu_ot
[BP_GET_TYPE(zio
->io_bp
)].ot_byteswap
;
2543 func(buf
->b_data
, hdr
->b_size
);
2546 arc_cksum_compute(buf
, B_FALSE
);
2548 if (hash_lock
&& zio
->io_error
== 0 && hdr
->b_state
== arc_anon
) {
2550 * Only call arc_access on anonymous buffers. This is because
2551 * if we've issued an I/O for an evicted buffer, we've already
2552 * called arc_access (to prevent any simultaneous readers from
2553 * getting confused).
2555 arc_access(hdr
, hash_lock
);
2558 /* create copies of the data buffer for the callers */
2560 for (acb
= callback_list
; acb
; acb
= acb
->acb_next
) {
2561 if (acb
->acb_done
) {
2563 abuf
= arc_buf_clone(buf
);
2564 acb
->acb_buf
= abuf
;
2569 hdr
->b_flags
&= ~ARC_IO_IN_PROGRESS
;
2570 ASSERT(!HDR_BUF_AVAILABLE(hdr
));
2572 ASSERT(buf
->b_efunc
== NULL
);
2573 ASSERT(hdr
->b_datacnt
== 1);
2574 hdr
->b_flags
|= ARC_BUF_AVAILABLE
;
2577 ASSERT(refcount_is_zero(&hdr
->b_refcnt
) || callback_list
!= NULL
);
2579 if (zio
->io_error
!= 0) {
2580 hdr
->b_flags
|= ARC_IO_ERROR
;
2581 if (hdr
->b_state
!= arc_anon
)
2582 arc_change_state(arc_anon
, hdr
, hash_lock
);
2583 if (HDR_IN_HASH_TABLE(hdr
))
2584 buf_hash_remove(hdr
);
2585 freeable
= refcount_is_zero(&hdr
->b_refcnt
);
2589 * Broadcast before we drop the hash_lock to avoid the possibility
2590 * that the hdr (and hence the cv) might be freed before we get to
2591 * the cv_broadcast().
2593 cv_broadcast(&hdr
->b_cv
);
2596 mutex_exit(hash_lock
);
2599 * This block was freed while we waited for the read to
2600 * complete. It has been removed from the hash table and
2601 * moved to the anonymous state (so that it won't show up
2604 ASSERT3P(hdr
->b_state
, ==, arc_anon
);
2605 freeable
= refcount_is_zero(&hdr
->b_refcnt
);
2608 /* execute each callback and free its structure */
2609 while ((acb
= callback_list
) != NULL
) {
2611 acb
->acb_done(zio
, acb
->acb_buf
, acb
->acb_private
);
2613 if (acb
->acb_zio_dummy
!= NULL
) {
2614 acb
->acb_zio_dummy
->io_error
= zio
->io_error
;
2615 zio_nowait(acb
->acb_zio_dummy
);
2618 callback_list
= acb
->acb_next
;
2619 kmem_free(acb
, sizeof (arc_callback_t
));
2623 arc_hdr_destroy(hdr
);
2627 * "Read" the block block at the specified DVA (in bp) via the
2628 * cache. If the block is found in the cache, invoke the provided
2629 * callback immediately and return. Note that the `zio' parameter
2630 * in the callback will be NULL in this case, since no IO was
2631 * required. If the block is not in the cache pass the read request
2632 * on to the spa with a substitute callback function, so that the
2633 * requested block will be added to the cache.
2635 * If a read request arrives for a block that has a read in-progress,
2636 * either wait for the in-progress read to complete (and return the
2637 * results); or, if this is a read with a "done" func, add a record
2638 * to the read to invoke the "done" func when the read completes,
2639 * and return; or just return.
2641 * arc_read_done() will invoke all the requested "done" functions
2642 * for readers of this block.
2644 * Normal callers should use arc_read and pass the arc buffer and offset
2645 * for the bp. But if you know you don't need locking, you can use
2649 arc_read(zio_t
*pio
, spa_t
*spa
, const blkptr_t
*bp
, arc_buf_t
*pbuf
,
2650 arc_done_func_t
*done
, void *private, int priority
, int zio_flags
,
2651 uint32_t *arc_flags
, const zbookmark_t
*zb
)
2657 * XXX This happens from traverse callback funcs, for
2658 * the objset_phys_t block.
2660 return (arc_read_nolock(pio
, spa
, bp
, done
, private, priority
,
2661 zio_flags
, arc_flags
, zb
));
2664 ASSERT(!refcount_is_zero(&pbuf
->b_hdr
->b_refcnt
));
2665 ASSERT3U((char *)bp
- (char *)pbuf
->b_data
, <, pbuf
->b_hdr
->b_size
);
2666 rw_enter(&pbuf
->b_data_lock
, RW_READER
);
2668 err
= arc_read_nolock(pio
, spa
, bp
, done
, private, priority
,
2669 zio_flags
, arc_flags
, zb
);
2670 rw_exit(&pbuf
->b_data_lock
);
2676 arc_read_nolock(zio_t
*pio
, spa_t
*spa
, const blkptr_t
*bp
,
2677 arc_done_func_t
*done
, void *private, int priority
, int zio_flags
,
2678 uint32_t *arc_flags
, const zbookmark_t
*zb
)
2681 arc_buf_t
*buf
= NULL
;
2682 kmutex_t
*hash_lock
;
2684 uint64_t guid
= spa_guid(spa
);
2687 hdr
= buf_hash_find(guid
, BP_IDENTITY(bp
), BP_PHYSICAL_BIRTH(bp
),
2689 if (hdr
&& hdr
->b_datacnt
> 0) {
2691 *arc_flags
|= ARC_CACHED
;
2693 if (HDR_IO_IN_PROGRESS(hdr
)) {
2695 if (*arc_flags
& ARC_WAIT
) {
2696 cv_wait(&hdr
->b_cv
, hash_lock
);
2697 mutex_exit(hash_lock
);
2700 ASSERT(*arc_flags
& ARC_NOWAIT
);
2703 arc_callback_t
*acb
= NULL
;
2705 acb
= kmem_zalloc(sizeof (arc_callback_t
),
2707 acb
->acb_done
= done
;
2708 acb
->acb_private
= private;
2710 acb
->acb_zio_dummy
= zio_null(pio
,
2711 spa
, NULL
, NULL
, NULL
, zio_flags
);
2713 ASSERT(acb
->acb_done
!= NULL
);
2714 acb
->acb_next
= hdr
->b_acb
;
2716 add_reference(hdr
, hash_lock
, private);
2717 mutex_exit(hash_lock
);
2720 mutex_exit(hash_lock
);
2724 ASSERT(hdr
->b_state
== arc_mru
|| hdr
->b_state
== arc_mfu
);
2727 add_reference(hdr
, hash_lock
, private);
2729 * If this block is already in use, create a new
2730 * copy of the data so that we will be guaranteed
2731 * that arc_release() will always succeed.
2735 ASSERT(buf
->b_data
);
2736 if (HDR_BUF_AVAILABLE(hdr
)) {
2737 ASSERT(buf
->b_efunc
== NULL
);
2738 hdr
->b_flags
&= ~ARC_BUF_AVAILABLE
;
2740 buf
= arc_buf_clone(buf
);
2743 } else if (*arc_flags
& ARC_PREFETCH
&&
2744 refcount_count(&hdr
->b_refcnt
) == 0) {
2745 hdr
->b_flags
|= ARC_PREFETCH
;
2747 DTRACE_PROBE1(arc__hit
, arc_buf_hdr_t
*, hdr
);
2748 arc_access(hdr
, hash_lock
);
2749 if (*arc_flags
& ARC_L2CACHE
)
2750 hdr
->b_flags
|= ARC_L2CACHE
;
2751 mutex_exit(hash_lock
);
2752 ARCSTAT_BUMP(arcstat_hits
);
2753 ARCSTAT_CONDSTAT(!(hdr
->b_flags
& ARC_PREFETCH
),
2754 demand
, prefetch
, hdr
->b_type
!= ARC_BUFC_METADATA
,
2755 data
, metadata
, hits
);
2758 done(NULL
, buf
, private);
2760 uint64_t size
= BP_GET_LSIZE(bp
);
2761 arc_callback_t
*acb
;
2764 boolean_t devw
= B_FALSE
;
2767 /* this block is not in the cache */
2768 arc_buf_hdr_t
*exists
;
2769 arc_buf_contents_t type
= BP_GET_BUFC_TYPE(bp
);
2770 buf
= arc_buf_alloc(spa
, size
, private, type
);
2772 hdr
->b_dva
= *BP_IDENTITY(bp
);
2773 hdr
->b_birth
= BP_PHYSICAL_BIRTH(bp
);
2774 hdr
->b_cksum0
= bp
->blk_cksum
.zc_word
[0];
2775 exists
= buf_hash_insert(hdr
, &hash_lock
);
2777 /* somebody beat us to the hash insert */
2778 mutex_exit(hash_lock
);
2779 buf_discard_identity(hdr
);
2780 (void) arc_buf_remove_ref(buf
, private);
2781 goto top
; /* restart the IO request */
2783 /* if this is a prefetch, we don't have a reference */
2784 if (*arc_flags
& ARC_PREFETCH
) {
2785 (void) remove_reference(hdr
, hash_lock
,
2787 hdr
->b_flags
|= ARC_PREFETCH
;
2789 if (*arc_flags
& ARC_L2CACHE
)
2790 hdr
->b_flags
|= ARC_L2CACHE
;
2791 if (BP_GET_LEVEL(bp
) > 0)
2792 hdr
->b_flags
|= ARC_INDIRECT
;
2794 /* this block is in the ghost cache */
2795 ASSERT(GHOST_STATE(hdr
->b_state
));
2796 ASSERT(!HDR_IO_IN_PROGRESS(hdr
));
2797 ASSERT3U(refcount_count(&hdr
->b_refcnt
), ==, 0);
2798 ASSERT(hdr
->b_buf
== NULL
);
2800 /* if this is a prefetch, we don't have a reference */
2801 if (*arc_flags
& ARC_PREFETCH
)
2802 hdr
->b_flags
|= ARC_PREFETCH
;
2804 add_reference(hdr
, hash_lock
, private);
2805 if (*arc_flags
& ARC_L2CACHE
)
2806 hdr
->b_flags
|= ARC_L2CACHE
;
2807 buf
= kmem_cache_alloc(buf_cache
, KM_PUSHPAGE
);
2810 buf
->b_efunc
= NULL
;
2811 buf
->b_private
= NULL
;
2814 ASSERT(hdr
->b_datacnt
== 0);
2816 arc_get_data_buf(buf
);
2817 arc_access(hdr
, hash_lock
);
2820 ASSERT(!GHOST_STATE(hdr
->b_state
));
2822 acb
= kmem_zalloc(sizeof (arc_callback_t
), KM_SLEEP
);
2823 acb
->acb_done
= done
;
2824 acb
->acb_private
= private;
2826 ASSERT(hdr
->b_acb
== NULL
);
2828 hdr
->b_flags
|= ARC_IO_IN_PROGRESS
;
2830 if (HDR_L2CACHE(hdr
) && hdr
->b_l2hdr
!= NULL
&&
2831 (vd
= hdr
->b_l2hdr
->b_dev
->l2ad_vdev
) != NULL
) {
2832 devw
= hdr
->b_l2hdr
->b_dev
->l2ad_writing
;
2833 addr
= hdr
->b_l2hdr
->b_daddr
;
2835 * Lock out device removal.
2837 if (vdev_is_dead(vd
) ||
2838 !spa_config_tryenter(spa
, SCL_L2ARC
, vd
, RW_READER
))
2842 mutex_exit(hash_lock
);
2844 ASSERT3U(hdr
->b_size
, ==, size
);
2845 DTRACE_PROBE4(arc__miss
, arc_buf_hdr_t
*, hdr
, blkptr_t
*, bp
,
2846 uint64_t, size
, zbookmark_t
*, zb
);
2847 ARCSTAT_BUMP(arcstat_misses
);
2848 ARCSTAT_CONDSTAT(!(hdr
->b_flags
& ARC_PREFETCH
),
2849 demand
, prefetch
, hdr
->b_type
!= ARC_BUFC_METADATA
,
2850 data
, metadata
, misses
);
2852 if (vd
!= NULL
&& l2arc_ndev
!= 0 && !(l2arc_norw
&& devw
)) {
2854 * Read from the L2ARC if the following are true:
2855 * 1. The L2ARC vdev was previously cached.
2856 * 2. This buffer still has L2ARC metadata.
2857 * 3. This buffer isn't currently writing to the L2ARC.
2858 * 4. The L2ARC entry wasn't evicted, which may
2859 * also have invalidated the vdev.
2860 * 5. This isn't prefetch and l2arc_noprefetch is set.
2862 if (hdr
->b_l2hdr
!= NULL
&&
2863 !HDR_L2_WRITING(hdr
) && !HDR_L2_EVICTED(hdr
) &&
2864 !(l2arc_noprefetch
&& HDR_PREFETCH(hdr
))) {
2865 l2arc_read_callback_t
*cb
;
2867 DTRACE_PROBE1(l2arc__hit
, arc_buf_hdr_t
*, hdr
);
2868 ARCSTAT_BUMP(arcstat_l2_hits
);
2870 cb
= kmem_zalloc(sizeof (l2arc_read_callback_t
),
2872 cb
->l2rcb_buf
= buf
;
2873 cb
->l2rcb_spa
= spa
;
2876 cb
->l2rcb_flags
= zio_flags
;
2879 * l2arc read. The SCL_L2ARC lock will be
2880 * released by l2arc_read_done().
2882 rzio
= zio_read_phys(pio
, vd
, addr
, size
,
2883 buf
->b_data
, ZIO_CHECKSUM_OFF
,
2884 l2arc_read_done
, cb
, priority
, zio_flags
|
2885 ZIO_FLAG_DONT_CACHE
| ZIO_FLAG_CANFAIL
|
2886 ZIO_FLAG_DONT_PROPAGATE
|
2887 ZIO_FLAG_DONT_RETRY
, B_FALSE
);
2888 DTRACE_PROBE2(l2arc__read
, vdev_t
*, vd
,
2890 ARCSTAT_INCR(arcstat_l2_read_bytes
, size
);
2892 if (*arc_flags
& ARC_NOWAIT
) {
2897 ASSERT(*arc_flags
& ARC_WAIT
);
2898 if (zio_wait(rzio
) == 0)
2901 /* l2arc read error; goto zio_read() */
2903 DTRACE_PROBE1(l2arc__miss
,
2904 arc_buf_hdr_t
*, hdr
);
2905 ARCSTAT_BUMP(arcstat_l2_misses
);
2906 if (HDR_L2_WRITING(hdr
))
2907 ARCSTAT_BUMP(arcstat_l2_rw_clash
);
2908 spa_config_exit(spa
, SCL_L2ARC
, vd
);
2912 spa_config_exit(spa
, SCL_L2ARC
, vd
);
2913 if (l2arc_ndev
!= 0) {
2914 DTRACE_PROBE1(l2arc__miss
,
2915 arc_buf_hdr_t
*, hdr
);
2916 ARCSTAT_BUMP(arcstat_l2_misses
);
2920 rzio
= zio_read(pio
, spa
, bp
, buf
->b_data
, size
,
2921 arc_read_done
, buf
, priority
, zio_flags
, zb
);
2923 if (*arc_flags
& ARC_WAIT
)
2924 return (zio_wait(rzio
));
2926 ASSERT(*arc_flags
& ARC_NOWAIT
);
2933 arc_set_callback(arc_buf_t
*buf
, arc_evict_func_t
*func
, void *private)
2935 ASSERT(buf
->b_hdr
!= NULL
);
2936 ASSERT(buf
->b_hdr
->b_state
!= arc_anon
);
2937 ASSERT(!refcount_is_zero(&buf
->b_hdr
->b_refcnt
) || func
== NULL
);
2938 ASSERT(buf
->b_efunc
== NULL
);
2939 ASSERT(!HDR_BUF_AVAILABLE(buf
->b_hdr
));
2941 buf
->b_efunc
= func
;
2942 buf
->b_private
= private;
2946 * This is used by the DMU to let the ARC know that a buffer is
2947 * being evicted, so the ARC should clean up. If this arc buf
2948 * is not yet in the evicted state, it will be put there.
2951 arc_buf_evict(arc_buf_t
*buf
)
2954 kmutex_t
*hash_lock
;
2957 mutex_enter(&buf
->b_evict_lock
);
2961 * We are in arc_do_user_evicts().
2963 ASSERT(buf
->b_data
== NULL
);
2964 mutex_exit(&buf
->b_evict_lock
);
2966 } else if (buf
->b_data
== NULL
) {
2967 arc_buf_t copy
= *buf
; /* structure assignment */
2969 * We are on the eviction list; process this buffer now
2970 * but let arc_do_user_evicts() do the reaping.
2972 buf
->b_efunc
= NULL
;
2973 mutex_exit(&buf
->b_evict_lock
);
2974 VERIFY(copy
.b_efunc(©
) == 0);
2977 hash_lock
= HDR_LOCK(hdr
);
2978 mutex_enter(hash_lock
);
2980 ASSERT3P(hash_lock
, ==, HDR_LOCK(hdr
));
2982 ASSERT3U(refcount_count(&hdr
->b_refcnt
), <, hdr
->b_datacnt
);
2983 ASSERT(hdr
->b_state
== arc_mru
|| hdr
->b_state
== arc_mfu
);
2986 * Pull this buffer off of the hdr
2989 while (*bufp
!= buf
)
2990 bufp
= &(*bufp
)->b_next
;
2991 *bufp
= buf
->b_next
;
2993 ASSERT(buf
->b_data
!= NULL
);
2994 arc_buf_destroy(buf
, FALSE
, FALSE
);
2996 if (hdr
->b_datacnt
== 0) {
2997 arc_state_t
*old_state
= hdr
->b_state
;
2998 arc_state_t
*evicted_state
;
3000 ASSERT(hdr
->b_buf
== NULL
);
3001 ASSERT(refcount_is_zero(&hdr
->b_refcnt
));
3004 (old_state
== arc_mru
) ? arc_mru_ghost
: arc_mfu_ghost
;
3006 mutex_enter(&old_state
->arcs_mtx
);
3007 mutex_enter(&evicted_state
->arcs_mtx
);
3009 arc_change_state(evicted_state
, hdr
, hash_lock
);
3010 ASSERT(HDR_IN_HASH_TABLE(hdr
));
3011 hdr
->b_flags
|= ARC_IN_HASH_TABLE
;
3012 hdr
->b_flags
&= ~ARC_BUF_AVAILABLE
;
3014 mutex_exit(&evicted_state
->arcs_mtx
);
3015 mutex_exit(&old_state
->arcs_mtx
);
3017 mutex_exit(hash_lock
);
3018 mutex_exit(&buf
->b_evict_lock
);
3020 VERIFY(buf
->b_efunc(buf
) == 0);
3021 buf
->b_efunc
= NULL
;
3022 buf
->b_private
= NULL
;
3025 kmem_cache_free(buf_cache
, buf
);
3030 * Release this buffer from the cache. This must be done
3031 * after a read and prior to modifying the buffer contents.
3032 * If the buffer has more than one reference, we must make
3033 * a new hdr for the buffer.
3036 arc_release(arc_buf_t
*buf
, void *tag
)
3039 kmutex_t
*hash_lock
= NULL
;
3040 l2arc_buf_hdr_t
*l2hdr
;
3041 uint64_t buf_size
= 0;
3044 * It would be nice to assert that if it's DMU metadata (level >
3045 * 0 || it's the dnode file), then it must be syncing context.
3046 * But we don't know that information at this level.
3049 mutex_enter(&buf
->b_evict_lock
);
3052 /* this buffer is not on any list */
3053 ASSERT(refcount_count(&hdr
->b_refcnt
) > 0);
3055 if (hdr
->b_state
== arc_anon
) {
3056 /* this buffer is already released */
3057 ASSERT(buf
->b_efunc
== NULL
);
3059 hash_lock
= HDR_LOCK(hdr
);
3060 mutex_enter(hash_lock
);
3062 ASSERT3P(hash_lock
, ==, HDR_LOCK(hdr
));
3065 l2hdr
= hdr
->b_l2hdr
;
3067 mutex_enter(&l2arc_buflist_mtx
);
3068 hdr
->b_l2hdr
= NULL
;
3069 buf_size
= hdr
->b_size
;
3073 * Do we have more than one buf?
3075 if (hdr
->b_datacnt
> 1) {
3076 arc_buf_hdr_t
*nhdr
;
3078 uint64_t blksz
= hdr
->b_size
;
3079 uint64_t spa
= hdr
->b_spa
;
3080 arc_buf_contents_t type
= hdr
->b_type
;
3081 uint32_t flags
= hdr
->b_flags
;
3083 ASSERT(hdr
->b_buf
!= buf
|| buf
->b_next
!= NULL
);
3085 * Pull the data off of this hdr and attach it to
3086 * a new anonymous hdr.
3088 (void) remove_reference(hdr
, hash_lock
, tag
);
3090 while (*bufp
!= buf
)
3091 bufp
= &(*bufp
)->b_next
;
3092 *bufp
= buf
->b_next
;
3095 ASSERT3U(hdr
->b_state
->arcs_size
, >=, hdr
->b_size
);
3096 atomic_add_64(&hdr
->b_state
->arcs_size
, -hdr
->b_size
);
3097 if (refcount_is_zero(&hdr
->b_refcnt
)) {
3098 uint64_t *size
= &hdr
->b_state
->arcs_lsize
[hdr
->b_type
];
3099 ASSERT3U(*size
, >=, hdr
->b_size
);
3100 atomic_add_64(size
, -hdr
->b_size
);
3102 hdr
->b_datacnt
-= 1;
3103 arc_cksum_verify(buf
);
3105 mutex_exit(hash_lock
);
3107 nhdr
= kmem_cache_alloc(hdr_cache
, KM_PUSHPAGE
);
3108 nhdr
->b_size
= blksz
;
3110 nhdr
->b_type
= type
;
3112 nhdr
->b_state
= arc_anon
;
3113 nhdr
->b_arc_access
= 0;
3114 nhdr
->b_flags
= flags
& ARC_L2_WRITING
;
3115 nhdr
->b_l2hdr
= NULL
;
3116 nhdr
->b_datacnt
= 1;
3117 nhdr
->b_freeze_cksum
= NULL
;
3118 (void) refcount_add(&nhdr
->b_refcnt
, tag
);
3120 mutex_exit(&buf
->b_evict_lock
);
3121 atomic_add_64(&arc_anon
->arcs_size
, blksz
);
3123 mutex_exit(&buf
->b_evict_lock
);
3124 ASSERT(refcount_count(&hdr
->b_refcnt
) == 1);
3125 ASSERT(!list_link_active(&hdr
->b_arc_node
));
3126 ASSERT(!HDR_IO_IN_PROGRESS(hdr
));
3127 if (hdr
->b_state
!= arc_anon
)
3128 arc_change_state(arc_anon
, hdr
, hash_lock
);
3129 hdr
->b_arc_access
= 0;
3131 mutex_exit(hash_lock
);
3133 buf_discard_identity(hdr
);
3136 buf
->b_efunc
= NULL
;
3137 buf
->b_private
= NULL
;
3140 list_remove(l2hdr
->b_dev
->l2ad_buflist
, hdr
);
3141 kmem_free(l2hdr
, sizeof (l2arc_buf_hdr_t
));
3142 ARCSTAT_INCR(arcstat_l2_size
, -buf_size
);
3143 mutex_exit(&l2arc_buflist_mtx
);
3148 * Release this buffer. If it does not match the provided BP, fill it
3149 * with that block's contents.
3153 arc_release_bp(arc_buf_t
*buf
, void *tag
, blkptr_t
*bp
, spa_t
*spa
,
3156 arc_release(buf
, tag
);
3161 arc_released(arc_buf_t
*buf
)
3165 mutex_enter(&buf
->b_evict_lock
);
3166 released
= (buf
->b_data
!= NULL
&& buf
->b_hdr
->b_state
== arc_anon
);
3167 mutex_exit(&buf
->b_evict_lock
);
3172 arc_has_callback(arc_buf_t
*buf
)
3176 mutex_enter(&buf
->b_evict_lock
);
3177 callback
= (buf
->b_efunc
!= NULL
);
3178 mutex_exit(&buf
->b_evict_lock
);
3184 arc_referenced(arc_buf_t
*buf
)
3188 mutex_enter(&buf
->b_evict_lock
);
3189 referenced
= (refcount_count(&buf
->b_hdr
->b_refcnt
));
3190 mutex_exit(&buf
->b_evict_lock
);
3191 return (referenced
);
3196 arc_write_ready(zio_t
*zio
)
3198 arc_write_callback_t
*callback
= zio
->io_private
;
3199 arc_buf_t
*buf
= callback
->awcb_buf
;
3200 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
3202 ASSERT(!refcount_is_zero(&buf
->b_hdr
->b_refcnt
));
3203 callback
->awcb_ready(zio
, buf
, callback
->awcb_private
);
3206 * If the IO is already in progress, then this is a re-write
3207 * attempt, so we need to thaw and re-compute the cksum.
3208 * It is the responsibility of the callback to handle the
3209 * accounting for any re-write attempt.
3211 if (HDR_IO_IN_PROGRESS(hdr
)) {
3212 mutex_enter(&hdr
->b_freeze_lock
);
3213 if (hdr
->b_freeze_cksum
!= NULL
) {
3214 kmem_free(hdr
->b_freeze_cksum
, sizeof (zio_cksum_t
));
3215 hdr
->b_freeze_cksum
= NULL
;
3217 mutex_exit(&hdr
->b_freeze_lock
);
3219 arc_cksum_compute(buf
, B_FALSE
);
3220 hdr
->b_flags
|= ARC_IO_IN_PROGRESS
;
3224 arc_write_done(zio_t
*zio
)
3226 arc_write_callback_t
*callback
= zio
->io_private
;
3227 arc_buf_t
*buf
= callback
->awcb_buf
;
3228 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
3230 ASSERT(hdr
->b_acb
== NULL
);
3232 if (zio
->io_error
== 0) {
3233 hdr
->b_dva
= *BP_IDENTITY(zio
->io_bp
);
3234 hdr
->b_birth
= BP_PHYSICAL_BIRTH(zio
->io_bp
);
3235 hdr
->b_cksum0
= zio
->io_bp
->blk_cksum
.zc_word
[0];
3237 ASSERT(BUF_EMPTY(hdr
));
3241 * If the block to be written was all-zero, we may have
3242 * compressed it away. In this case no write was performed
3243 * so there will be no dva/birth/checksum. The buffer must
3244 * therefore remain anonymous (and uncached).
3246 if (!BUF_EMPTY(hdr
)) {
3247 arc_buf_hdr_t
*exists
;
3248 kmutex_t
*hash_lock
;
3250 ASSERT(zio
->io_error
== 0);
3252 arc_cksum_verify(buf
);
3254 exists
= buf_hash_insert(hdr
, &hash_lock
);
3257 * This can only happen if we overwrite for
3258 * sync-to-convergence, because we remove
3259 * buffers from the hash table when we arc_free().
3261 if (zio
->io_flags
& ZIO_FLAG_IO_REWRITE
) {
3262 if (!BP_EQUAL(&zio
->io_bp_orig
, zio
->io_bp
))
3263 panic("bad overwrite, hdr=%p exists=%p",
3264 (void *)hdr
, (void *)exists
);
3265 ASSERT(refcount_is_zero(&exists
->b_refcnt
));
3266 arc_change_state(arc_anon
, exists
, hash_lock
);
3267 mutex_exit(hash_lock
);
3268 arc_hdr_destroy(exists
);
3269 exists
= buf_hash_insert(hdr
, &hash_lock
);
3270 ASSERT3P(exists
, ==, NULL
);
3273 ASSERT(hdr
->b_datacnt
== 1);
3274 ASSERT(hdr
->b_state
== arc_anon
);
3275 ASSERT(BP_GET_DEDUP(zio
->io_bp
));
3276 ASSERT(BP_GET_LEVEL(zio
->io_bp
) == 0);
3279 hdr
->b_flags
&= ~ARC_IO_IN_PROGRESS
;
3280 /* if it's not anon, we are doing a scrub */
3281 if (!exists
&& hdr
->b_state
== arc_anon
)
3282 arc_access(hdr
, hash_lock
);
3283 mutex_exit(hash_lock
);
3285 hdr
->b_flags
&= ~ARC_IO_IN_PROGRESS
;
3288 ASSERT(!refcount_is_zero(&hdr
->b_refcnt
));
3289 callback
->awcb_done(zio
, buf
, callback
->awcb_private
);
3291 kmem_free(callback
, sizeof (arc_write_callback_t
));
3295 arc_write(zio_t
*pio
, spa_t
*spa
, uint64_t txg
,
3296 blkptr_t
*bp
, arc_buf_t
*buf
, boolean_t l2arc
, const zio_prop_t
*zp
,
3297 arc_done_func_t
*ready
, arc_done_func_t
*done
, void *private,
3298 int priority
, int zio_flags
, const zbookmark_t
*zb
)
3300 arc_buf_hdr_t
*hdr
= buf
->b_hdr
;
3301 arc_write_callback_t
*callback
;
3304 ASSERT(ready
!= NULL
);
3305 ASSERT(done
!= NULL
);
3306 ASSERT(!HDR_IO_ERROR(hdr
));
3307 ASSERT((hdr
->b_flags
& ARC_IO_IN_PROGRESS
) == 0);
3308 ASSERT(hdr
->b_acb
== NULL
);
3310 hdr
->b_flags
|= ARC_L2CACHE
;
3311 callback
= kmem_zalloc(sizeof (arc_write_callback_t
), KM_SLEEP
);
3312 callback
->awcb_ready
= ready
;
3313 callback
->awcb_done
= done
;
3314 callback
->awcb_private
= private;
3315 callback
->awcb_buf
= buf
;
3317 zio
= zio_write(pio
, spa
, txg
, bp
, buf
->b_data
, hdr
->b_size
, zp
,
3318 arc_write_ready
, arc_write_done
, callback
, priority
, zio_flags
, zb
);
3324 arc_memory_throttle(uint64_t reserve
, uint64_t inflight_data
, uint64_t txg
)
3327 uint64_t available_memory
= ptob(freemem
);
3328 static uint64_t page_load
= 0;
3329 static uint64_t last_txg
= 0;
3333 MIN(available_memory
, vmem_size(heap_arena
, VMEM_FREE
));
3335 if (available_memory
>= zfs_write_limit_max
)
3338 if (txg
> last_txg
) {
3343 * If we are in pageout, we know that memory is already tight,
3344 * the arc is already going to be evicting, so we just want to
3345 * continue to let page writes occur as quickly as possible.
3347 if (curproc
== proc_pageout
) {
3348 if (page_load
> MAX(ptob(minfree
), available_memory
) / 4)
3350 /* Note: reserve is inflated, so we deflate */
3351 page_load
+= reserve
/ 8;
3353 } else if (page_load
> 0 && arc_reclaim_needed()) {
3354 /* memory is low, delay before restarting */
3355 ARCSTAT_INCR(arcstat_memory_throttle_count
, 1);
3360 if (arc_size
> arc_c_min
) {
3361 uint64_t evictable_memory
=
3362 arc_mru
->arcs_lsize
[ARC_BUFC_DATA
] +
3363 arc_mru
->arcs_lsize
[ARC_BUFC_METADATA
] +
3364 arc_mfu
->arcs_lsize
[ARC_BUFC_DATA
] +
3365 arc_mfu
->arcs_lsize
[ARC_BUFC_METADATA
];
3366 available_memory
+= MIN(evictable_memory
, arc_size
- arc_c_min
);
3369 if (inflight_data
> available_memory
/ 4) {
3370 ARCSTAT_INCR(arcstat_memory_throttle_count
, 1);
3378 arc_tempreserve_clear(uint64_t reserve
)
3380 atomic_add_64(&arc_tempreserve
, -reserve
);
3381 ASSERT((int64_t)arc_tempreserve
>= 0);
3385 arc_tempreserve_space(uint64_t reserve
, uint64_t txg
)
3392 * Once in a while, fail for no reason. Everything should cope.
3394 if (spa_get_random(10000) == 0) {
3395 dprintf("forcing random failure\n");
3399 if (reserve
> arc_c
/4 && !arc_no_grow
)
3400 arc_c
= MIN(arc_c_max
, reserve
* 4);
3401 if (reserve
> arc_c
)
3405 * Don't count loaned bufs as in flight dirty data to prevent long
3406 * network delays from blocking transactions that are ready to be
3407 * assigned to a txg.
3409 anon_size
= MAX((int64_t)(arc_anon
->arcs_size
- arc_loaned_bytes
), 0);
3412 * Writes will, almost always, require additional memory allocations
3413 * in order to compress/encrypt/etc the data. We therefor need to
3414 * make sure that there is sufficient available memory for this.
3416 if ((error
= arc_memory_throttle(reserve
, anon_size
, txg
)))
3420 * Throttle writes when the amount of dirty data in the cache
3421 * gets too large. We try to keep the cache less than half full
3422 * of dirty blocks so that our sync times don't grow too large.
3423 * Note: if two requests come in concurrently, we might let them
3424 * both succeed, when one of them should fail. Not a huge deal.
3427 if (reserve
+ arc_tempreserve
+ anon_size
> arc_c
/ 2 &&
3428 anon_size
> arc_c
/ 4) {
3429 dprintf("failing, arc_tempreserve=%lluK anon_meta=%lluK "
3430 "anon_data=%lluK tempreserve=%lluK arc_c=%lluK\n",
3431 arc_tempreserve
>>10,
3432 arc_anon
->arcs_lsize
[ARC_BUFC_METADATA
]>>10,
3433 arc_anon
->arcs_lsize
[ARC_BUFC_DATA
]>>10,
3434 reserve
>>10, arc_c
>>10);
3437 atomic_add_64(&arc_tempreserve
, reserve
);
3444 mutex_init(&arc_reclaim_thr_lock
, NULL
, MUTEX_DEFAULT
, NULL
);
3445 cv_init(&arc_reclaim_thr_cv
, NULL
, CV_DEFAULT
, NULL
);
3447 /* Convert seconds to clock ticks */
3448 arc_min_prefetch_lifespan
= 1 * hz
;
3450 /* Start out with 1/8 of all memory */
3451 arc_c
= physmem
* PAGESIZE
/ 8;
3455 * On architectures where the physical memory can be larger
3456 * than the addressable space (intel in 32-bit mode), we may
3457 * need to limit the cache to 1/8 of VM size.
3459 arc_c
= MIN(arc_c
, vmem_size(heap_arena
, VMEM_ALLOC
| VMEM_FREE
) / 8);
3462 /* set min cache to 1/32 of all memory, or 64MB, whichever is more */
3463 arc_c_min
= MAX(arc_c
/ 4, 64<<20);
3464 /* set max to 3/4 of all memory, or all but 1GB, whichever is more */
3465 if (arc_c
* 8 >= 1<<30)
3466 arc_c_max
= (arc_c
* 8) - (1<<30);
3468 arc_c_max
= arc_c_min
;
3469 arc_c_max
= MAX(arc_c
* 6, arc_c_max
);
3472 * Allow the tunables to override our calculations if they are
3473 * reasonable (ie. over 64MB)
3475 if (zfs_arc_max
> 64<<20 && zfs_arc_max
< physmem
* PAGESIZE
)
3476 arc_c_max
= zfs_arc_max
;
3477 if (zfs_arc_min
> 64<<20 && zfs_arc_min
<= arc_c_max
)
3478 arc_c_min
= zfs_arc_min
;
3481 arc_p
= (arc_c
>> 1);
3483 /* limit meta-data to 1/4 of the arc capacity */
3484 arc_meta_limit
= arc_c_max
/ 4;
3486 /* Allow the tunable to override if it is reasonable */
3487 if (zfs_arc_meta_limit
> 0 && zfs_arc_meta_limit
<= arc_c_max
)
3488 arc_meta_limit
= zfs_arc_meta_limit
;
3490 if (arc_c_min
< arc_meta_limit
/ 2 && zfs_arc_min
== 0)
3491 arc_c_min
= arc_meta_limit
/ 2;
3493 if (zfs_arc_grow_retry
> 0)
3494 arc_grow_retry
= zfs_arc_grow_retry
;
3496 if (zfs_arc_shrink_shift
> 0)
3497 arc_shrink_shift
= zfs_arc_shrink_shift
;
3499 if (zfs_arc_p_min_shift
> 0)
3500 arc_p_min_shift
= zfs_arc_p_min_shift
;
3502 /* if kmem_flags are set, lets try to use less memory */
3503 if (kmem_debugging())
3505 if (arc_c
< arc_c_min
)
3508 arc_anon
= &ARC_anon
;
3510 arc_mru_ghost
= &ARC_mru_ghost
;
3512 arc_mfu_ghost
= &ARC_mfu_ghost
;
3513 arc_l2c_only
= &ARC_l2c_only
;
3516 mutex_init(&arc_anon
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3517 mutex_init(&arc_mru
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3518 mutex_init(&arc_mru_ghost
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3519 mutex_init(&arc_mfu
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3520 mutex_init(&arc_mfu_ghost
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3521 mutex_init(&arc_l2c_only
->arcs_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3523 list_create(&arc_mru
->arcs_list
[ARC_BUFC_METADATA
],
3524 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3525 list_create(&arc_mru
->arcs_list
[ARC_BUFC_DATA
],
3526 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3527 list_create(&arc_mru_ghost
->arcs_list
[ARC_BUFC_METADATA
],
3528 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3529 list_create(&arc_mru_ghost
->arcs_list
[ARC_BUFC_DATA
],
3530 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3531 list_create(&arc_mfu
->arcs_list
[ARC_BUFC_METADATA
],
3532 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3533 list_create(&arc_mfu
->arcs_list
[ARC_BUFC_DATA
],
3534 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3535 list_create(&arc_mfu_ghost
->arcs_list
[ARC_BUFC_METADATA
],
3536 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3537 list_create(&arc_mfu_ghost
->arcs_list
[ARC_BUFC_DATA
],
3538 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3539 list_create(&arc_l2c_only
->arcs_list
[ARC_BUFC_METADATA
],
3540 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3541 list_create(&arc_l2c_only
->arcs_list
[ARC_BUFC_DATA
],
3542 sizeof (arc_buf_hdr_t
), offsetof(arc_buf_hdr_t
, b_arc_node
));
3546 arc_thread_exit
= 0;
3547 arc_eviction_list
= NULL
;
3548 mutex_init(&arc_eviction_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
3549 bzero(&arc_eviction_hdr
, sizeof (arc_buf_hdr_t
));
3551 arc_ksp
= kstat_create("zfs", 0, "arcstats", "misc", KSTAT_TYPE_NAMED
,
3552 sizeof (arc_stats
) / sizeof (kstat_named_t
), KSTAT_FLAG_VIRTUAL
);
3554 if (arc_ksp
!= NULL
) {
3555 arc_ksp
->ks_data
= &arc_stats
;
3556 kstat_install(arc_ksp
);
3559 (void) thread_create(NULL
, 0, arc_reclaim_thread
, NULL
, 0, &p0
,
3560 TS_RUN
, minclsyspri
);
3565 if (zfs_write_limit_max
== 0)
3566 zfs_write_limit_max
= ptob(physmem
) >> zfs_write_limit_shift
;
3568 zfs_write_limit_shift
= 0;
3569 mutex_init(&zfs_write_limit_lock
, NULL
, MUTEX_DEFAULT
, NULL
);
3575 mutex_enter(&arc_reclaim_thr_lock
);
3576 arc_thread_exit
= 1;
3577 while (arc_thread_exit
!= 0)
3578 cv_wait(&arc_reclaim_thr_cv
, &arc_reclaim_thr_lock
);
3579 mutex_exit(&arc_reclaim_thr_lock
);
3585 if (arc_ksp
!= NULL
) {
3586 kstat_delete(arc_ksp
);
3590 mutex_destroy(&arc_eviction_mtx
);
3591 mutex_destroy(&arc_reclaim_thr_lock
);
3592 cv_destroy(&arc_reclaim_thr_cv
);
3594 list_destroy(&arc_mru
->arcs_list
[ARC_BUFC_METADATA
]);
3595 list_destroy(&arc_mru_ghost
->arcs_list
[ARC_BUFC_METADATA
]);
3596 list_destroy(&arc_mfu
->arcs_list
[ARC_BUFC_METADATA
]);
3597 list_destroy(&arc_mfu_ghost
->arcs_list
[ARC_BUFC_METADATA
]);
3598 list_destroy(&arc_mru
->arcs_list
[ARC_BUFC_DATA
]);
3599 list_destroy(&arc_mru_ghost
->arcs_list
[ARC_BUFC_DATA
]);
3600 list_destroy(&arc_mfu
->arcs_list
[ARC_BUFC_DATA
]);
3601 list_destroy(&arc_mfu_ghost
->arcs_list
[ARC_BUFC_DATA
]);
3603 mutex_destroy(&arc_anon
->arcs_mtx
);
3604 mutex_destroy(&arc_mru
->arcs_mtx
);
3605 mutex_destroy(&arc_mru_ghost
->arcs_mtx
);
3606 mutex_destroy(&arc_mfu
->arcs_mtx
);
3607 mutex_destroy(&arc_mfu_ghost
->arcs_mtx
);
3608 mutex_destroy(&arc_l2c_only
->arcs_mtx
);
3610 mutex_destroy(&zfs_write_limit_lock
);
3614 ASSERT(arc_loaned_bytes
== 0);
3620 * The level 2 ARC (L2ARC) is a cache layer in-between main memory and disk.
3621 * It uses dedicated storage devices to hold cached data, which are populated
3622 * using large infrequent writes. The main role of this cache is to boost
3623 * the performance of random read workloads. The intended L2ARC devices
3624 * include short-stroked disks, solid state disks, and other media with
3625 * substantially faster read latency than disk.
3627 * +-----------------------+
3629 * +-----------------------+
3632 * l2arc_feed_thread() arc_read()
3636 * +---------------+ |
3638 * +---------------+ |
3643 * +-------+ +-------+
3645 * | cache | | cache |
3646 * +-------+ +-------+
3647 * +=========+ .-----.
3648 * : L2ARC : |-_____-|
3649 * : devices : | Disks |
3650 * +=========+ `-_____-'
3652 * Read requests are satisfied from the following sources, in order:
3655 * 2) vdev cache of L2ARC devices
3657 * 4) vdev cache of disks
3660 * Some L2ARC device types exhibit extremely slow write performance.
3661 * To accommodate for this there are some significant differences between
3662 * the L2ARC and traditional cache design:
3664 * 1. There is no eviction path from the ARC to the L2ARC. Evictions from
3665 * the ARC behave as usual, freeing buffers and placing headers on ghost
3666 * lists. The ARC does not send buffers to the L2ARC during eviction as
3667 * this would add inflated write latencies for all ARC memory pressure.
3669 * 2. The L2ARC attempts to cache data from the ARC before it is evicted.
3670 * It does this by periodically scanning buffers from the eviction-end of
3671 * the MFU and MRU ARC lists, copying them to the L2ARC devices if they are
3672 * not already there. It scans until a headroom of buffers is satisfied,
3673 * which itself is a buffer for ARC eviction. The thread that does this is
3674 * l2arc_feed_thread(), illustrated below; example sizes are included to
3675 * provide a better sense of ratio than this diagram:
3678 * +---------------------+----------+
3679 * ARC_mfu |:::::#:::::::::::::::|o#o###o###|-->. # already on L2ARC
3680 * +---------------------+----------+ | o L2ARC eligible
3681 * ARC_mru |:#:::::::::::::::::::|#o#ooo####|-->| : ARC buffer
3682 * +---------------------+----------+ |
3683 * 15.9 Gbytes ^ 32 Mbytes |
3685 * l2arc_feed_thread()
3687 * l2arc write hand <--[oooo]--'
3691 * +==============================+
3692 * L2ARC dev |####|#|###|###| |####| ... |
3693 * +==============================+
3696 * 3. If an ARC buffer is copied to the L2ARC but then hit instead of
3697 * evicted, then the L2ARC has cached a buffer much sooner than it probably
3698 * needed to, potentially wasting L2ARC device bandwidth and storage. It is
3699 * safe to say that this is an uncommon case, since buffers at the end of
3700 * the ARC lists have moved there due to inactivity.
3702 * 4. If the ARC evicts faster than the L2ARC can maintain a headroom,
3703 * then the L2ARC simply misses copying some buffers. This serves as a
3704 * pressure valve to prevent heavy read workloads from both stalling the ARC
3705 * with waits and clogging the L2ARC with writes. This also helps prevent
3706 * the potential for the L2ARC to churn if it attempts to cache content too
3707 * quickly, such as during backups of the entire pool.
3709 * 5. After system boot and before the ARC has filled main memory, there are
3710 * no evictions from the ARC and so the tails of the ARC_mfu and ARC_mru
3711 * lists can remain mostly static. Instead of searching from tail of these
3712 * lists as pictured, the l2arc_feed_thread() will search from the list heads
3713 * for eligible buffers, greatly increasing its chance of finding them.
3715 * The L2ARC device write speed is also boosted during this time so that
3716 * the L2ARC warms up faster. Since there have been no ARC evictions yet,
3717 * there are no L2ARC reads, and no fear of degrading read performance
3718 * through increased writes.
3720 * 6. Writes to the L2ARC devices are grouped and sent in-sequence, so that
3721 * the vdev queue can aggregate them into larger and fewer writes. Each
3722 * device is written to in a rotor fashion, sweeping writes through
3723 * available space then repeating.
3725 * 7. The L2ARC does not store dirty content. It never needs to flush
3726 * write buffers back to disk based storage.
3728 * 8. If an ARC buffer is written (and dirtied) which also exists in the
3729 * L2ARC, the now stale L2ARC buffer is immediately dropped.
3731 * The performance of the L2ARC can be tweaked by a number of tunables, which
3732 * may be necessary for different workloads:
3734 * l2arc_write_max max write bytes per interval
3735 * l2arc_write_boost extra write bytes during device warmup
3736 * l2arc_noprefetch skip caching prefetched buffers
3737 * l2arc_headroom number of max device writes to precache
3738 * l2arc_feed_secs seconds between L2ARC writing
3740 * Tunables may be removed or added as future performance improvements are
3741 * integrated, and also may become zpool properties.
3743 * There are three key functions that control how the L2ARC warms up:
3745 * l2arc_write_eligible() check if a buffer is eligible to cache
3746 * l2arc_write_size() calculate how much to write
3747 * l2arc_write_interval() calculate sleep delay between writes
3749 * These three functions determine what to write, how much, and how quickly
3754 l2arc_write_eligible(uint64_t spa_guid
, arc_buf_hdr_t
*ab
)
3757 * A buffer is *not* eligible for the L2ARC if it:
3758 * 1. belongs to a different spa.
3759 * 2. is already cached on the L2ARC.
3760 * 3. has an I/O in progress (it may be an incomplete read).
3761 * 4. is flagged not eligible (zfs property).
3763 if (ab
->b_spa
!= spa_guid
|| ab
->b_l2hdr
!= NULL
||
3764 HDR_IO_IN_PROGRESS(ab
) || !HDR_L2CACHE(ab
))
3771 l2arc_write_size(l2arc_dev_t
*dev
)
3775 size
= dev
->l2ad_write
;
3777 if (arc_warm
== B_FALSE
)
3778 size
+= dev
->l2ad_boost
;
3785 l2arc_write_interval(clock_t began
, uint64_t wanted
, uint64_t wrote
)
3787 clock_t interval
, next
, now
;
3790 * If the ARC lists are busy, increase our write rate; if the
3791 * lists are stale, idle back. This is achieved by checking
3792 * how much we previously wrote - if it was more than half of
3793 * what we wanted, schedule the next write much sooner.
3795 if (l2arc_feed_again
&& wrote
> (wanted
/ 2))
3796 interval
= (hz
* l2arc_feed_min_ms
) / 1000;
3798 interval
= hz
* l2arc_feed_secs
;
3800 now
= ddi_get_lbolt();
3801 next
= MAX(now
, MIN(now
+ interval
, began
+ interval
));
3807 l2arc_hdr_stat_add(void)
3809 ARCSTAT_INCR(arcstat_l2_hdr_size
, HDR_SIZE
+ L2HDR_SIZE
);
3810 ARCSTAT_INCR(arcstat_hdr_size
, -HDR_SIZE
);
3814 l2arc_hdr_stat_remove(void)
3816 ARCSTAT_INCR(arcstat_l2_hdr_size
, -(HDR_SIZE
+ L2HDR_SIZE
));
3817 ARCSTAT_INCR(arcstat_hdr_size
, HDR_SIZE
);
3821 * Cycle through L2ARC devices. This is how L2ARC load balances.
3822 * If a device is returned, this also returns holding the spa config lock.
3824 static l2arc_dev_t
*
3825 l2arc_dev_get_next(void)
3827 l2arc_dev_t
*first
, *next
= NULL
;
3830 * Lock out the removal of spas (spa_namespace_lock), then removal
3831 * of cache devices (l2arc_dev_mtx). Once a device has been selected,
3832 * both locks will be dropped and a spa config lock held instead.
3834 mutex_enter(&spa_namespace_lock
);
3835 mutex_enter(&l2arc_dev_mtx
);
3837 /* if there are no vdevs, there is nothing to do */
3838 if (l2arc_ndev
== 0)
3842 next
= l2arc_dev_last
;
3844 /* loop around the list looking for a non-faulted vdev */
3846 next
= list_head(l2arc_dev_list
);
3848 next
= list_next(l2arc_dev_list
, next
);
3850 next
= list_head(l2arc_dev_list
);
3853 /* if we have come back to the start, bail out */
3856 else if (next
== first
)
3859 } while (vdev_is_dead(next
->l2ad_vdev
));
3861 /* if we were unable to find any usable vdevs, return NULL */
3862 if (vdev_is_dead(next
->l2ad_vdev
))
3865 l2arc_dev_last
= next
;
3868 mutex_exit(&l2arc_dev_mtx
);
3871 * Grab the config lock to prevent the 'next' device from being
3872 * removed while we are writing to it.
3875 spa_config_enter(next
->l2ad_spa
, SCL_L2ARC
, next
, RW_READER
);
3876 mutex_exit(&spa_namespace_lock
);
3882 * Free buffers that were tagged for destruction.
3885 l2arc_do_free_on_write(void)
3888 l2arc_data_free_t
*df
, *df_prev
;
3890 mutex_enter(&l2arc_free_on_write_mtx
);
3891 buflist
= l2arc_free_on_write
;
3893 for (df
= list_tail(buflist
); df
; df
= df_prev
) {
3894 df_prev
= list_prev(buflist
, df
);
3895 ASSERT(df
->l2df_data
!= NULL
);
3896 ASSERT(df
->l2df_func
!= NULL
);
3897 df
->l2df_func(df
->l2df_data
, df
->l2df_size
);
3898 list_remove(buflist
, df
);
3899 kmem_free(df
, sizeof (l2arc_data_free_t
));
3902 mutex_exit(&l2arc_free_on_write_mtx
);
3906 * A write to a cache device has completed. Update all headers to allow
3907 * reads from these buffers to begin.
3910 l2arc_write_done(zio_t
*zio
)
3912 l2arc_write_callback_t
*cb
;
3915 arc_buf_hdr_t
*head
, *ab
, *ab_prev
;
3916 l2arc_buf_hdr_t
*abl2
;
3917 kmutex_t
*hash_lock
;
3919 cb
= zio
->io_private
;
3921 dev
= cb
->l2wcb_dev
;
3922 ASSERT(dev
!= NULL
);
3923 head
= cb
->l2wcb_head
;
3924 ASSERT(head
!= NULL
);
3925 buflist
= dev
->l2ad_buflist
;
3926 ASSERT(buflist
!= NULL
);
3927 DTRACE_PROBE2(l2arc__iodone
, zio_t
*, zio
,
3928 l2arc_write_callback_t
*, cb
);
3930 if (zio
->io_error
!= 0)
3931 ARCSTAT_BUMP(arcstat_l2_writes_error
);
3933 mutex_enter(&l2arc_buflist_mtx
);
3936 * All writes completed, or an error was hit.
3938 for (ab
= list_prev(buflist
, head
); ab
; ab
= ab_prev
) {
3939 ab_prev
= list_prev(buflist
, ab
);
3941 hash_lock
= HDR_LOCK(ab
);
3942 if (!mutex_tryenter(hash_lock
)) {
3944 * This buffer misses out. It may be in a stage
3945 * of eviction. Its ARC_L2_WRITING flag will be
3946 * left set, denying reads to this buffer.
3948 ARCSTAT_BUMP(arcstat_l2_writes_hdr_miss
);
3952 if (zio
->io_error
!= 0) {
3954 * Error - drop L2ARC entry.
3956 list_remove(buflist
, ab
);
3959 kmem_free(abl2
, sizeof (l2arc_buf_hdr_t
));
3960 ARCSTAT_INCR(arcstat_l2_size
, -ab
->b_size
);
3964 * Allow ARC to begin reads to this L2ARC entry.
3966 ab
->b_flags
&= ~ARC_L2_WRITING
;
3968 mutex_exit(hash_lock
);
3971 atomic_inc_64(&l2arc_writes_done
);
3972 list_remove(buflist
, head
);
3973 kmem_cache_free(hdr_cache
, head
);
3974 mutex_exit(&l2arc_buflist_mtx
);
3976 l2arc_do_free_on_write();
3978 kmem_free(cb
, sizeof (l2arc_write_callback_t
));
3982 * A read to a cache device completed. Validate buffer contents before
3983 * handing over to the regular ARC routines.
3986 l2arc_read_done(zio_t
*zio
)
3988 l2arc_read_callback_t
*cb
;
3991 kmutex_t
*hash_lock
;
3994 ASSERT(zio
->io_vd
!= NULL
);
3995 ASSERT(zio
->io_flags
& ZIO_FLAG_DONT_PROPAGATE
);
3997 spa_config_exit(zio
->io_spa
, SCL_L2ARC
, zio
->io_vd
);
3999 cb
= zio
->io_private
;
4001 buf
= cb
->l2rcb_buf
;
4002 ASSERT(buf
!= NULL
);
4004 hash_lock
= HDR_LOCK(buf
->b_hdr
);
4005 mutex_enter(hash_lock
);
4007 ASSERT3P(hash_lock
, ==, HDR_LOCK(hdr
));
4010 * Check this survived the L2ARC journey.
4012 equal
= arc_cksum_equal(buf
);
4013 if (equal
&& zio
->io_error
== 0 && !HDR_L2_EVICTED(hdr
)) {
4014 mutex_exit(hash_lock
);
4015 zio
->io_private
= buf
;
4016 zio
->io_bp_copy
= cb
->l2rcb_bp
; /* XXX fix in L2ARC 2.0 */
4017 zio
->io_bp
= &zio
->io_bp_copy
; /* XXX fix in L2ARC 2.0 */
4020 mutex_exit(hash_lock
);
4022 * Buffer didn't survive caching. Increment stats and
4023 * reissue to the original storage device.
4025 if (zio
->io_error
!= 0) {
4026 ARCSTAT_BUMP(arcstat_l2_io_error
);
4028 zio
->io_error
= EIO
;
4031 ARCSTAT_BUMP(arcstat_l2_cksum_bad
);
4034 * If there's no waiter, issue an async i/o to the primary
4035 * storage now. If there *is* a waiter, the caller must
4036 * issue the i/o in a context where it's OK to block.
4038 if (zio
->io_waiter
== NULL
) {
4039 zio_t
*pio
= zio_unique_parent(zio
);
4041 ASSERT(!pio
|| pio
->io_child_type
== ZIO_CHILD_LOGICAL
);
4043 zio_nowait(zio_read(pio
, cb
->l2rcb_spa
, &cb
->l2rcb_bp
,
4044 buf
->b_data
, zio
->io_size
, arc_read_done
, buf
,
4045 zio
->io_priority
, cb
->l2rcb_flags
, &cb
->l2rcb_zb
));
4049 kmem_free(cb
, sizeof (l2arc_read_callback_t
));
4053 * This is the list priority from which the L2ARC will search for pages to
4054 * cache. This is used within loops (0..3) to cycle through lists in the
4055 * desired order. This order can have a significant effect on cache
4058 * Currently the metadata lists are hit first, MFU then MRU, followed by
4059 * the data lists. This function returns a locked list, and also returns
4063 l2arc_list_locked(int list_num
, kmutex_t
**lock
)
4065 list_t
*list
= NULL
;
4067 ASSERT(list_num
>= 0 && list_num
<= 3);
4071 list
= &arc_mfu
->arcs_list
[ARC_BUFC_METADATA
];
4072 *lock
= &arc_mfu
->arcs_mtx
;
4075 list
= &arc_mru
->arcs_list
[ARC_BUFC_METADATA
];
4076 *lock
= &arc_mru
->arcs_mtx
;
4079 list
= &arc_mfu
->arcs_list
[ARC_BUFC_DATA
];
4080 *lock
= &arc_mfu
->arcs_mtx
;
4083 list
= &arc_mru
->arcs_list
[ARC_BUFC_DATA
];
4084 *lock
= &arc_mru
->arcs_mtx
;
4088 ASSERT(!(MUTEX_HELD(*lock
)));
4094 * Evict buffers from the device write hand to the distance specified in
4095 * bytes. This distance may span populated buffers, it may span nothing.
4096 * This is clearing a region on the L2ARC device ready for writing.
4097 * If the 'all' boolean is set, every buffer is evicted.
4100 l2arc_evict(l2arc_dev_t
*dev
, uint64_t distance
, boolean_t all
)
4103 l2arc_buf_hdr_t
*abl2
;
4104 arc_buf_hdr_t
*ab
, *ab_prev
;
4105 kmutex_t
*hash_lock
;
4108 buflist
= dev
->l2ad_buflist
;
4110 if (buflist
== NULL
)
4113 if (!all
&& dev
->l2ad_first
) {
4115 * This is the first sweep through the device. There is
4121 if (dev
->l2ad_hand
>= (dev
->l2ad_end
- (2 * distance
))) {
4123 * When nearing the end of the device, evict to the end
4124 * before the device write hand jumps to the start.
4126 taddr
= dev
->l2ad_end
;
4128 taddr
= dev
->l2ad_hand
+ distance
;
4130 DTRACE_PROBE4(l2arc__evict
, l2arc_dev_t
*, dev
, list_t
*, buflist
,
4131 uint64_t, taddr
, boolean_t
, all
);
4134 mutex_enter(&l2arc_buflist_mtx
);
4135 for (ab
= list_tail(buflist
); ab
; ab
= ab_prev
) {
4136 ab_prev
= list_prev(buflist
, ab
);
4138 hash_lock
= HDR_LOCK(ab
);
4139 if (!mutex_tryenter(hash_lock
)) {
4141 * Missed the hash lock. Retry.
4143 ARCSTAT_BUMP(arcstat_l2_evict_lock_retry
);
4144 mutex_exit(&l2arc_buflist_mtx
);
4145 mutex_enter(hash_lock
);
4146 mutex_exit(hash_lock
);
4150 if (HDR_L2_WRITE_HEAD(ab
)) {
4152 * We hit a write head node. Leave it for
4153 * l2arc_write_done().
4155 list_remove(buflist
, ab
);
4156 mutex_exit(hash_lock
);
4160 if (!all
&& ab
->b_l2hdr
!= NULL
&&
4161 (ab
->b_l2hdr
->b_daddr
> taddr
||
4162 ab
->b_l2hdr
->b_daddr
< dev
->l2ad_hand
)) {
4164 * We've evicted to the target address,
4165 * or the end of the device.
4167 mutex_exit(hash_lock
);
4171 if (HDR_FREE_IN_PROGRESS(ab
)) {
4173 * Already on the path to destruction.
4175 mutex_exit(hash_lock
);
4179 if (ab
->b_state
== arc_l2c_only
) {
4180 ASSERT(!HDR_L2_READING(ab
));
4182 * This doesn't exist in the ARC. Destroy.
4183 * arc_hdr_destroy() will call list_remove()
4184 * and decrement arcstat_l2_size.
4186 arc_change_state(arc_anon
, ab
, hash_lock
);
4187 arc_hdr_destroy(ab
);
4190 * Invalidate issued or about to be issued
4191 * reads, since we may be about to write
4192 * over this location.
4194 if (HDR_L2_READING(ab
)) {
4195 ARCSTAT_BUMP(arcstat_l2_evict_reading
);
4196 ab
->b_flags
|= ARC_L2_EVICTED
;
4200 * Tell ARC this no longer exists in L2ARC.
4202 if (ab
->b_l2hdr
!= NULL
) {
4205 kmem_free(abl2
, sizeof (l2arc_buf_hdr_t
));
4206 ARCSTAT_INCR(arcstat_l2_size
, -ab
->b_size
);
4208 list_remove(buflist
, ab
);
4211 * This may have been leftover after a
4214 ab
->b_flags
&= ~ARC_L2_WRITING
;
4216 mutex_exit(hash_lock
);
4218 mutex_exit(&l2arc_buflist_mtx
);
4220 vdev_space_update(dev
->l2ad_vdev
, -(taddr
- dev
->l2ad_evict
), 0, 0);
4221 dev
->l2ad_evict
= taddr
;
4225 * Find and write ARC buffers to the L2ARC device.
4227 * An ARC_L2_WRITING flag is set so that the L2ARC buffers are not valid
4228 * for reading until they have completed writing.
4231 l2arc_write_buffers(spa_t
*spa
, l2arc_dev_t
*dev
, uint64_t target_sz
)
4233 arc_buf_hdr_t
*ab
, *ab_prev
, *head
;
4234 l2arc_buf_hdr_t
*hdrl2
;
4236 uint64_t passed_sz
, write_sz
, buf_sz
, headroom
;
4238 kmutex_t
*hash_lock
, *list_lock
= NULL
;
4239 boolean_t have_lock
, full
;
4240 l2arc_write_callback_t
*cb
;
4242 uint64_t guid
= spa_guid(spa
);
4245 ASSERT(dev
->l2ad_vdev
!= NULL
);
4250 head
= kmem_cache_alloc(hdr_cache
, KM_PUSHPAGE
);
4251 head
->b_flags
|= ARC_L2_WRITE_HEAD
;
4254 * Copy buffers for L2ARC writing.
4256 mutex_enter(&l2arc_buflist_mtx
);
4257 for (try = 0; try <= 3; try++) {
4258 list
= l2arc_list_locked(try, &list_lock
);
4262 * L2ARC fast warmup.
4264 * Until the ARC is warm and starts to evict, read from the
4265 * head of the ARC lists rather than the tail.
4267 headroom
= target_sz
* l2arc_headroom
;
4268 if (arc_warm
== B_FALSE
)
4269 ab
= list_head(list
);
4271 ab
= list_tail(list
);
4273 for (; ab
; ab
= ab_prev
) {
4274 if (arc_warm
== B_FALSE
)
4275 ab_prev
= list_next(list
, ab
);
4277 ab_prev
= list_prev(list
, ab
);
4279 hash_lock
= HDR_LOCK(ab
);
4280 have_lock
= MUTEX_HELD(hash_lock
);
4281 if (!have_lock
&& !mutex_tryenter(hash_lock
)) {
4283 * Skip this buffer rather than waiting.
4288 passed_sz
+= ab
->b_size
;
4289 if (passed_sz
> headroom
) {
4293 mutex_exit(hash_lock
);
4297 if (!l2arc_write_eligible(guid
, ab
)) {
4298 mutex_exit(hash_lock
);
4302 if ((write_sz
+ ab
->b_size
) > target_sz
) {
4304 mutex_exit(hash_lock
);
4310 * Insert a dummy header on the buflist so
4311 * l2arc_write_done() can find where the
4312 * write buffers begin without searching.
4314 list_insert_head(dev
->l2ad_buflist
, head
);
4317 sizeof (l2arc_write_callback_t
), KM_SLEEP
);
4318 cb
->l2wcb_dev
= dev
;
4319 cb
->l2wcb_head
= head
;
4320 pio
= zio_root(spa
, l2arc_write_done
, cb
,
4325 * Create and add a new L2ARC header.
4327 hdrl2
= kmem_zalloc(sizeof (l2arc_buf_hdr_t
), KM_SLEEP
);
4329 hdrl2
->b_daddr
= dev
->l2ad_hand
;
4331 ab
->b_flags
|= ARC_L2_WRITING
;
4332 ab
->b_l2hdr
= hdrl2
;
4333 list_insert_head(dev
->l2ad_buflist
, ab
);
4334 buf_data
= ab
->b_buf
->b_data
;
4335 buf_sz
= ab
->b_size
;
4338 * Compute and store the buffer cksum before
4339 * writing. On debug the cksum is verified first.
4341 arc_cksum_verify(ab
->b_buf
);
4342 arc_cksum_compute(ab
->b_buf
, B_TRUE
);
4344 mutex_exit(hash_lock
);
4346 wzio
= zio_write_phys(pio
, dev
->l2ad_vdev
,
4347 dev
->l2ad_hand
, buf_sz
, buf_data
, ZIO_CHECKSUM_OFF
,
4348 NULL
, NULL
, ZIO_PRIORITY_ASYNC_WRITE
,
4349 ZIO_FLAG_CANFAIL
, B_FALSE
);
4351 DTRACE_PROBE2(l2arc__write
, vdev_t
*, dev
->l2ad_vdev
,
4353 (void) zio_nowait(wzio
);
4356 * Keep the clock hand suitably device-aligned.
4358 buf_sz
= vdev_psize_to_asize(dev
->l2ad_vdev
, buf_sz
);
4361 dev
->l2ad_hand
+= buf_sz
;
4364 mutex_exit(list_lock
);
4369 mutex_exit(&l2arc_buflist_mtx
);
4372 ASSERT3U(write_sz
, ==, 0);
4373 kmem_cache_free(hdr_cache
, head
);
4377 ASSERT3U(write_sz
, <=, target_sz
);
4378 ARCSTAT_BUMP(arcstat_l2_writes_sent
);
4379 ARCSTAT_INCR(arcstat_l2_write_bytes
, write_sz
);
4380 ARCSTAT_INCR(arcstat_l2_size
, write_sz
);
4381 vdev_space_update(dev
->l2ad_vdev
, write_sz
, 0, 0);
4384 * Bump device hand to the device start if it is approaching the end.
4385 * l2arc_evict() will already have evicted ahead for this case.
4387 if (dev
->l2ad_hand
>= (dev
->l2ad_end
- target_sz
)) {
4388 vdev_space_update(dev
->l2ad_vdev
,
4389 dev
->l2ad_end
- dev
->l2ad_hand
, 0, 0);
4390 dev
->l2ad_hand
= dev
->l2ad_start
;
4391 dev
->l2ad_evict
= dev
->l2ad_start
;
4392 dev
->l2ad_first
= B_FALSE
;
4395 dev
->l2ad_writing
= B_TRUE
;
4396 (void) zio_wait(pio
);
4397 dev
->l2ad_writing
= B_FALSE
;
4403 * This thread feeds the L2ARC at regular intervals. This is the beating
4404 * heart of the L2ARC.
4407 l2arc_feed_thread(void)
4412 uint64_t size
, wrote
;
4413 clock_t begin
, next
= ddi_get_lbolt();
4415 CALLB_CPR_INIT(&cpr
, &l2arc_feed_thr_lock
, callb_generic_cpr
, FTAG
);
4417 mutex_enter(&l2arc_feed_thr_lock
);
4419 while (l2arc_thread_exit
== 0) {
4420 CALLB_CPR_SAFE_BEGIN(&cpr
);
4421 (void) cv_timedwait(&l2arc_feed_thr_cv
, &l2arc_feed_thr_lock
,
4423 CALLB_CPR_SAFE_END(&cpr
, &l2arc_feed_thr_lock
);
4424 next
= ddi_get_lbolt() + hz
;
4427 * Quick check for L2ARC devices.
4429 mutex_enter(&l2arc_dev_mtx
);
4430 if (l2arc_ndev
== 0) {
4431 mutex_exit(&l2arc_dev_mtx
);
4434 mutex_exit(&l2arc_dev_mtx
);
4435 begin
= ddi_get_lbolt();
4438 * This selects the next l2arc device to write to, and in
4439 * doing so the next spa to feed from: dev->l2ad_spa. This
4440 * will return NULL if there are now no l2arc devices or if
4441 * they are all faulted.
4443 * If a device is returned, its spa's config lock is also
4444 * held to prevent device removal. l2arc_dev_get_next()
4445 * will grab and release l2arc_dev_mtx.
4447 if ((dev
= l2arc_dev_get_next()) == NULL
)
4450 spa
= dev
->l2ad_spa
;
4451 ASSERT(spa
!= NULL
);
4454 * If the pool is read-only then force the feed thread to
4455 * sleep a little longer.
4457 if (!spa_writeable(spa
)) {
4458 next
= ddi_get_lbolt() + 5 * l2arc_feed_secs
* hz
;
4459 spa_config_exit(spa
, SCL_L2ARC
, dev
);
4464 * Avoid contributing to memory pressure.
4466 if (arc_reclaim_needed()) {
4467 ARCSTAT_BUMP(arcstat_l2_abort_lowmem
);
4468 spa_config_exit(spa
, SCL_L2ARC
, dev
);
4472 ARCSTAT_BUMP(arcstat_l2_feeds
);
4474 size
= l2arc_write_size(dev
);
4477 * Evict L2ARC buffers that will be overwritten.
4479 l2arc_evict(dev
, size
, B_FALSE
);
4482 * Write ARC buffers.
4484 wrote
= l2arc_write_buffers(spa
, dev
, size
);
4487 * Calculate interval between writes.
4489 next
= l2arc_write_interval(begin
, size
, wrote
);
4490 spa_config_exit(spa
, SCL_L2ARC
, dev
);
4493 l2arc_thread_exit
= 0;
4494 cv_broadcast(&l2arc_feed_thr_cv
);
4495 CALLB_CPR_EXIT(&cpr
); /* drops l2arc_feed_thr_lock */
4500 l2arc_vdev_present(vdev_t
*vd
)
4504 mutex_enter(&l2arc_dev_mtx
);
4505 for (dev
= list_head(l2arc_dev_list
); dev
!= NULL
;
4506 dev
= list_next(l2arc_dev_list
, dev
)) {
4507 if (dev
->l2ad_vdev
== vd
)
4510 mutex_exit(&l2arc_dev_mtx
);
4512 return (dev
!= NULL
);
4516 * Add a vdev for use by the L2ARC. By this point the spa has already
4517 * validated the vdev and opened it.
4520 l2arc_add_vdev(spa_t
*spa
, vdev_t
*vd
)
4522 l2arc_dev_t
*adddev
;
4524 ASSERT(!l2arc_vdev_present(vd
));
4527 * Create a new l2arc device entry.
4529 adddev
= kmem_zalloc(sizeof (l2arc_dev_t
), KM_SLEEP
);
4530 adddev
->l2ad_spa
= spa
;
4531 adddev
->l2ad_vdev
= vd
;
4532 adddev
->l2ad_write
= l2arc_write_max
;
4533 adddev
->l2ad_boost
= l2arc_write_boost
;
4534 adddev
->l2ad_start
= VDEV_LABEL_START_SIZE
;
4535 adddev
->l2ad_end
= VDEV_LABEL_START_SIZE
+ vdev_get_min_asize(vd
);
4536 adddev
->l2ad_hand
= adddev
->l2ad_start
;
4537 adddev
->l2ad_evict
= adddev
->l2ad_start
;
4538 adddev
->l2ad_first
= B_TRUE
;
4539 adddev
->l2ad_writing
= B_FALSE
;
4540 ASSERT3U(adddev
->l2ad_write
, >, 0);
4543 * This is a list of all ARC buffers that are still valid on the
4546 adddev
->l2ad_buflist
= kmem_zalloc(sizeof (list_t
), KM_SLEEP
);
4547 list_create(adddev
->l2ad_buflist
, sizeof (arc_buf_hdr_t
),
4548 offsetof(arc_buf_hdr_t
, b_l2node
));
4550 vdev_space_update(vd
, 0, 0, adddev
->l2ad_end
- adddev
->l2ad_hand
);
4553 * Add device to global list
4555 mutex_enter(&l2arc_dev_mtx
);
4556 list_insert_head(l2arc_dev_list
, adddev
);
4557 atomic_inc_64(&l2arc_ndev
);
4558 mutex_exit(&l2arc_dev_mtx
);
4562 * Remove a vdev from the L2ARC.
4565 l2arc_remove_vdev(vdev_t
*vd
)
4567 l2arc_dev_t
*dev
, *nextdev
, *remdev
= NULL
;
4570 * Find the device by vdev
4572 mutex_enter(&l2arc_dev_mtx
);
4573 for (dev
= list_head(l2arc_dev_list
); dev
; dev
= nextdev
) {
4574 nextdev
= list_next(l2arc_dev_list
, dev
);
4575 if (vd
== dev
->l2ad_vdev
) {
4580 ASSERT(remdev
!= NULL
);
4583 * Remove device from global list
4585 list_remove(l2arc_dev_list
, remdev
);
4586 l2arc_dev_last
= NULL
; /* may have been invalidated */
4587 atomic_dec_64(&l2arc_ndev
);
4588 mutex_exit(&l2arc_dev_mtx
);
4591 * Clear all buflists and ARC references. L2ARC device flush.
4593 l2arc_evict(remdev
, 0, B_TRUE
);
4594 list_destroy(remdev
->l2ad_buflist
);
4595 kmem_free(remdev
->l2ad_buflist
, sizeof (list_t
));
4596 kmem_free(remdev
, sizeof (l2arc_dev_t
));
4602 l2arc_thread_exit
= 0;
4604 l2arc_writes_sent
= 0;
4605 l2arc_writes_done
= 0;
4607 mutex_init(&l2arc_feed_thr_lock
, NULL
, MUTEX_DEFAULT
, NULL
);
4608 cv_init(&l2arc_feed_thr_cv
, NULL
, CV_DEFAULT
, NULL
);
4609 mutex_init(&l2arc_dev_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
4610 mutex_init(&l2arc_buflist_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
4611 mutex_init(&l2arc_free_on_write_mtx
, NULL
, MUTEX_DEFAULT
, NULL
);
4613 l2arc_dev_list
= &L2ARC_dev_list
;
4614 l2arc_free_on_write
= &L2ARC_free_on_write
;
4615 list_create(l2arc_dev_list
, sizeof (l2arc_dev_t
),
4616 offsetof(l2arc_dev_t
, l2ad_node
));
4617 list_create(l2arc_free_on_write
, sizeof (l2arc_data_free_t
),
4618 offsetof(l2arc_data_free_t
, l2df_list_node
));
4625 * This is called from dmu_fini(), which is called from spa_fini();
4626 * Because of this, we can assume that all l2arc devices have
4627 * already been removed when the pools themselves were removed.
4630 l2arc_do_free_on_write();
4632 mutex_destroy(&l2arc_feed_thr_lock
);
4633 cv_destroy(&l2arc_feed_thr_cv
);
4634 mutex_destroy(&l2arc_dev_mtx
);
4635 mutex_destroy(&l2arc_buflist_mtx
);
4636 mutex_destroy(&l2arc_free_on_write_mtx
);
4638 list_destroy(l2arc_dev_list
);
4639 list_destroy(l2arc_free_on_write
);
4645 if (!(spa_mode_global
& FWRITE
))
4648 (void) thread_create(NULL
, 0, l2arc_feed_thread
, NULL
, 0, &p0
,
4649 TS_RUN
, minclsyspri
);
4655 if (!(spa_mode_global
& FWRITE
))
4658 mutex_enter(&l2arc_feed_thr_lock
);
4659 cv_signal(&l2arc_feed_thr_cv
); /* kick thread out of startup */
4660 l2arc_thread_exit
= 1;
4661 while (l2arc_thread_exit
!= 0)
4662 cv_wait(&l2arc_feed_thr_cv
, &l2arc_feed_thr_lock
);
4663 mutex_exit(&l2arc_feed_thr_lock
);