Commit | Line | Data |
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cafe5635 KO |
1 | /* |
2 | * Primary bucket allocation code | |
3 | * | |
4 | * Copyright 2012 Google, Inc. | |
5 | * | |
6 | * Allocation in bcache is done in terms of buckets: | |
7 | * | |
8 | * Each bucket has associated an 8 bit gen; this gen corresponds to the gen in | |
9 | * btree pointers - they must match for the pointer to be considered valid. | |
10 | * | |
11 | * Thus (assuming a bucket has no dirty data or metadata in it) we can reuse a | |
12 | * bucket simply by incrementing its gen. | |
13 | * | |
14 | * The gens (along with the priorities; it's really the gens are important but | |
15 | * the code is named as if it's the priorities) are written in an arbitrary list | |
16 | * of buckets on disk, with a pointer to them in the journal header. | |
17 | * | |
18 | * When we invalidate a bucket, we have to write its new gen to disk and wait | |
19 | * for that write to complete before we use it - otherwise after a crash we | |
20 | * could have pointers that appeared to be good but pointed to data that had | |
21 | * been overwritten. | |
22 | * | |
23 | * Since the gens and priorities are all stored contiguously on disk, we can | |
24 | * batch this up: We fill up the free_inc list with freshly invalidated buckets, | |
25 | * call prio_write(), and when prio_write() finishes we pull buckets off the | |
26 | * free_inc list and optionally discard them. | |
27 | * | |
28 | * free_inc isn't the only freelist - if it was, we'd often to sleep while | |
29 | * priorities and gens were being written before we could allocate. c->free is a | |
30 | * smaller freelist, and buckets on that list are always ready to be used. | |
31 | * | |
32 | * If we've got discards enabled, that happens when a bucket moves from the | |
33 | * free_inc list to the free list. | |
34 | * | |
35 | * There is another freelist, because sometimes we have buckets that we know | |
36 | * have nothing pointing into them - these we can reuse without waiting for | |
37 | * priorities to be rewritten. These come from freed btree nodes and buckets | |
38 | * that garbage collection discovered no longer had valid keys pointing into | |
39 | * them (because they were overwritten). That's the unused list - buckets on the | |
40 | * unused list move to the free list, optionally being discarded in the process. | |
41 | * | |
42 | * It's also important to ensure that gens don't wrap around - with respect to | |
43 | * either the oldest gen in the btree or the gen on disk. This is quite | |
44 | * difficult to do in practice, but we explicitly guard against it anyways - if | |
45 | * a bucket is in danger of wrapping around we simply skip invalidating it that | |
46 | * time around, and we garbage collect or rewrite the priorities sooner than we | |
47 | * would have otherwise. | |
48 | * | |
49 | * bch_bucket_alloc() allocates a single bucket from a specific cache. | |
50 | * | |
51 | * bch_bucket_alloc_set() allocates one or more buckets from different caches | |
52 | * out of a cache set. | |
53 | * | |
54 | * free_some_buckets() drives all the processes described above. It's called | |
55 | * from bch_bucket_alloc() and a few other places that need to make sure free | |
56 | * buckets are ready. | |
57 | * | |
58 | * invalidate_buckets_(lru|fifo)() find buckets that are available to be | |
59 | * invalidated, and then invalidate them and stick them on the free_inc list - | |
60 | * in either lru or fifo order. | |
61 | */ | |
62 | ||
63 | #include "bcache.h" | |
64 | #include "btree.h" | |
65 | ||
49b1212d | 66 | #include <linux/blkdev.h> |
79826c35 | 67 | #include <linux/freezer.h> |
119ba0f8 | 68 | #include <linux/kthread.h> |
cafe5635 | 69 | #include <linux/random.h> |
c37511b8 | 70 | #include <trace/events/bcache.h> |
cafe5635 | 71 | |
cafe5635 KO |
72 | /* Bucket heap / gen */ |
73 | ||
74 | uint8_t bch_inc_gen(struct cache *ca, struct bucket *b) | |
75 | { | |
76 | uint8_t ret = ++b->gen; | |
77 | ||
78 | ca->set->need_gc = max(ca->set->need_gc, bucket_gc_gen(b)); | |
79 | WARN_ON_ONCE(ca->set->need_gc > BUCKET_GC_GEN_MAX); | |
80 | ||
cafe5635 KO |
81 | return ret; |
82 | } | |
83 | ||
84 | void bch_rescale_priorities(struct cache_set *c, int sectors) | |
85 | { | |
86 | struct cache *ca; | |
87 | struct bucket *b; | |
88 | unsigned next = c->nbuckets * c->sb.bucket_size / 1024; | |
89 | unsigned i; | |
90 | int r; | |
91 | ||
92 | atomic_sub(sectors, &c->rescale); | |
93 | ||
94 | do { | |
95 | r = atomic_read(&c->rescale); | |
96 | ||
97 | if (r >= 0) | |
98 | return; | |
99 | } while (atomic_cmpxchg(&c->rescale, r, r + next) != r); | |
100 | ||
101 | mutex_lock(&c->bucket_lock); | |
102 | ||
103 | c->min_prio = USHRT_MAX; | |
104 | ||
105 | for_each_cache(ca, c, i) | |
106 | for_each_bucket(b, ca) | |
107 | if (b->prio && | |
108 | b->prio != BTREE_PRIO && | |
109 | !atomic_read(&b->pin)) { | |
110 | b->prio--; | |
111 | c->min_prio = min(c->min_prio, b->prio); | |
112 | } | |
113 | ||
114 | mutex_unlock(&c->bucket_lock); | |
115 | } | |
116 | ||
2531d9ee KO |
117 | /* |
118 | * Background allocation thread: scans for buckets to be invalidated, | |
119 | * invalidates them, rewrites prios/gens (marking them as invalidated on disk), | |
120 | * then optionally issues discard commands to the newly free buckets, then puts | |
121 | * them on the various freelists. | |
122 | */ | |
cafe5635 KO |
123 | |
124 | static inline bool can_inc_bucket_gen(struct bucket *b) | |
125 | { | |
2531d9ee | 126 | return bucket_gc_gen(b) < BUCKET_GC_GEN_MAX; |
cafe5635 KO |
127 | } |
128 | ||
2531d9ee | 129 | bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b) |
cafe5635 | 130 | { |
2531d9ee | 131 | BUG_ON(!ca->set->gc_mark_valid); |
cafe5635 | 132 | |
4fe6a816 KO |
133 | return (!GC_MARK(b) || |
134 | GC_MARK(b) == GC_MARK_RECLAIMABLE) && | |
cafe5635 KO |
135 | !atomic_read(&b->pin) && |
136 | can_inc_bucket_gen(b); | |
137 | } | |
138 | ||
2531d9ee | 139 | void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b) |
cafe5635 | 140 | { |
2531d9ee KO |
141 | lockdep_assert_held(&ca->set->bucket_lock); |
142 | BUG_ON(GC_MARK(b) && GC_MARK(b) != GC_MARK_RECLAIMABLE); | |
7159b1ad KO |
143 | |
144 | if (GC_SECTORS_USED(b)) | |
2531d9ee | 145 | trace_bcache_invalidate(ca, b - ca->buckets); |
7159b1ad | 146 | |
cafe5635 KO |
147 | bch_inc_gen(ca, b); |
148 | b->prio = INITIAL_PRIO; | |
149 | atomic_inc(&b->pin); | |
2531d9ee KO |
150 | } |
151 | ||
152 | static void bch_invalidate_one_bucket(struct cache *ca, struct bucket *b) | |
153 | { | |
154 | __bch_invalidate_one_bucket(ca, b); | |
155 | ||
156 | fifo_push(&ca->free_inc, b - ca->buckets); | |
cafe5635 KO |
157 | } |
158 | ||
e0a985a4 KO |
159 | /* |
160 | * Determines what order we're going to reuse buckets, smallest bucket_prio() | |
161 | * first: we also take into account the number of sectors of live data in that | |
162 | * bucket, and in order for that multiply to make sense we have to scale bucket | |
163 | * | |
164 | * Thus, we scale the bucket priorities so that the bucket with the smallest | |
165 | * prio is worth 1/8th of what INITIAL_PRIO is worth. | |
166 | */ | |
167 | ||
168 | #define bucket_prio(b) \ | |
169 | ({ \ | |
170 | unsigned min_prio = (INITIAL_PRIO - ca->set->min_prio) / 8; \ | |
171 | \ | |
172 | (b->prio - ca->set->min_prio + min_prio) * GC_SECTORS_USED(b); \ | |
173 | }) | |
cafe5635 | 174 | |
b1a67b0f KO |
175 | #define bucket_max_cmp(l, r) (bucket_prio(l) < bucket_prio(r)) |
176 | #define bucket_min_cmp(l, r) (bucket_prio(l) > bucket_prio(r)) | |
cafe5635 | 177 | |
b1a67b0f KO |
178 | static void invalidate_buckets_lru(struct cache *ca) |
179 | { | |
cafe5635 KO |
180 | struct bucket *b; |
181 | ssize_t i; | |
182 | ||
183 | ca->heap.used = 0; | |
184 | ||
185 | for_each_bucket(b, ca) { | |
2531d9ee | 186 | if (!bch_can_invalidate_bucket(ca, b)) |
86b26b82 KO |
187 | continue; |
188 | ||
189 | if (!heap_full(&ca->heap)) | |
190 | heap_add(&ca->heap, b, bucket_max_cmp); | |
191 | else if (bucket_max_cmp(b, heap_peek(&ca->heap))) { | |
192 | ca->heap.data[0] = b; | |
193 | heap_sift(&ca->heap, 0, bucket_max_cmp); | |
cafe5635 KO |
194 | } |
195 | } | |
196 | ||
cafe5635 KO |
197 | for (i = ca->heap.used / 2 - 1; i >= 0; --i) |
198 | heap_sift(&ca->heap, i, bucket_min_cmp); | |
199 | ||
200 | while (!fifo_full(&ca->free_inc)) { | |
201 | if (!heap_pop(&ca->heap, b, bucket_min_cmp)) { | |
86b26b82 KO |
202 | /* |
203 | * We don't want to be calling invalidate_buckets() | |
cafe5635 KO |
204 | * multiple times when it can't do anything |
205 | */ | |
206 | ca->invalidate_needs_gc = 1; | |
72a44517 | 207 | wake_up_gc(ca->set); |
cafe5635 KO |
208 | return; |
209 | } | |
210 | ||
2531d9ee | 211 | bch_invalidate_one_bucket(ca, b); |
cafe5635 KO |
212 | } |
213 | } | |
214 | ||
215 | static void invalidate_buckets_fifo(struct cache *ca) | |
216 | { | |
217 | struct bucket *b; | |
218 | size_t checked = 0; | |
219 | ||
220 | while (!fifo_full(&ca->free_inc)) { | |
221 | if (ca->fifo_last_bucket < ca->sb.first_bucket || | |
222 | ca->fifo_last_bucket >= ca->sb.nbuckets) | |
223 | ca->fifo_last_bucket = ca->sb.first_bucket; | |
224 | ||
225 | b = ca->buckets + ca->fifo_last_bucket++; | |
226 | ||
2531d9ee KO |
227 | if (bch_can_invalidate_bucket(ca, b)) |
228 | bch_invalidate_one_bucket(ca, b); | |
cafe5635 KO |
229 | |
230 | if (++checked >= ca->sb.nbuckets) { | |
231 | ca->invalidate_needs_gc = 1; | |
72a44517 | 232 | wake_up_gc(ca->set); |
cafe5635 KO |
233 | return; |
234 | } | |
235 | } | |
236 | } | |
237 | ||
238 | static void invalidate_buckets_random(struct cache *ca) | |
239 | { | |
240 | struct bucket *b; | |
241 | size_t checked = 0; | |
242 | ||
243 | while (!fifo_full(&ca->free_inc)) { | |
244 | size_t n; | |
245 | get_random_bytes(&n, sizeof(n)); | |
246 | ||
247 | n %= (size_t) (ca->sb.nbuckets - ca->sb.first_bucket); | |
248 | n += ca->sb.first_bucket; | |
249 | ||
250 | b = ca->buckets + n; | |
251 | ||
2531d9ee KO |
252 | if (bch_can_invalidate_bucket(ca, b)) |
253 | bch_invalidate_one_bucket(ca, b); | |
cafe5635 KO |
254 | |
255 | if (++checked >= ca->sb.nbuckets / 2) { | |
256 | ca->invalidate_needs_gc = 1; | |
72a44517 | 257 | wake_up_gc(ca->set); |
cafe5635 KO |
258 | return; |
259 | } | |
260 | } | |
261 | } | |
262 | ||
263 | static void invalidate_buckets(struct cache *ca) | |
264 | { | |
2531d9ee | 265 | BUG_ON(ca->invalidate_needs_gc); |
cafe5635 KO |
266 | |
267 | switch (CACHE_REPLACEMENT(&ca->sb)) { | |
268 | case CACHE_REPLACEMENT_LRU: | |
269 | invalidate_buckets_lru(ca); | |
270 | break; | |
271 | case CACHE_REPLACEMENT_FIFO: | |
272 | invalidate_buckets_fifo(ca); | |
273 | break; | |
274 | case CACHE_REPLACEMENT_RANDOM: | |
275 | invalidate_buckets_random(ca); | |
276 | break; | |
277 | } | |
278 | } | |
279 | ||
280 | #define allocator_wait(ca, cond) \ | |
281 | do { \ | |
86b26b82 | 282 | while (1) { \ |
119ba0f8 | 283 | set_current_state(TASK_INTERRUPTIBLE); \ |
86b26b82 KO |
284 | if (cond) \ |
285 | break; \ | |
cafe5635 KO |
286 | \ |
287 | mutex_unlock(&(ca)->set->bucket_lock); \ | |
79826c35 | 288 | if (kthread_should_stop()) \ |
119ba0f8 | 289 | return 0; \ |
cafe5635 | 290 | \ |
79826c35 | 291 | try_to_freeze(); \ |
cafe5635 | 292 | schedule(); \ |
cafe5635 KO |
293 | mutex_lock(&(ca)->set->bucket_lock); \ |
294 | } \ | |
119ba0f8 | 295 | __set_current_state(TASK_RUNNING); \ |
cafe5635 KO |
296 | } while (0) |
297 | ||
78365411 KO |
298 | static int bch_allocator_push(struct cache *ca, long bucket) |
299 | { | |
300 | unsigned i; | |
301 | ||
302 | /* Prios/gens are actually the most important reserve */ | |
303 | if (fifo_push(&ca->free[RESERVE_PRIO], bucket)) | |
304 | return true; | |
305 | ||
306 | for (i = 0; i < RESERVE_NR; i++) | |
307 | if (fifo_push(&ca->free[i], bucket)) | |
308 | return true; | |
309 | ||
310 | return false; | |
311 | } | |
312 | ||
119ba0f8 | 313 | static int bch_allocator_thread(void *arg) |
cafe5635 | 314 | { |
119ba0f8 | 315 | struct cache *ca = arg; |
cafe5635 KO |
316 | |
317 | mutex_lock(&ca->set->bucket_lock); | |
318 | ||
319 | while (1) { | |
86b26b82 KO |
320 | /* |
321 | * First, we pull buckets off of the unused and free_inc lists, | |
322 | * possibly issue discards to them, then we add the bucket to | |
323 | * the free list: | |
324 | */ | |
2531d9ee | 325 | while (!fifo_empty(&ca->free_inc)) { |
cafe5635 KO |
326 | long bucket; |
327 | ||
2531d9ee | 328 | fifo_pop(&ca->free_inc, bucket); |
cafe5635 | 329 | |
cafe5635 | 330 | if (ca->discard) { |
49b1212d KO |
331 | mutex_unlock(&ca->set->bucket_lock); |
332 | blkdev_issue_discard(ca->bdev, | |
333 | bucket_to_sector(ca->set, bucket), | |
8b326d3a | 334 | ca->sb.bucket_size, GFP_KERNEL, 0); |
49b1212d | 335 | mutex_lock(&ca->set->bucket_lock); |
cafe5635 | 336 | } |
49b1212d | 337 | |
78365411 | 338 | allocator_wait(ca, bch_allocator_push(ca, bucket)); |
0a63b66d | 339 | wake_up(&ca->set->btree_cache_wait); |
35fcd848 | 340 | wake_up(&ca->set->bucket_wait); |
cafe5635 KO |
341 | } |
342 | ||
86b26b82 KO |
343 | /* |
344 | * We've run out of free buckets, we need to find some buckets | |
345 | * we can invalidate. First, invalidate them in memory and add | |
346 | * them to the free_inc list: | |
347 | */ | |
cafe5635 | 348 | |
2531d9ee | 349 | retry_invalidate: |
86b26b82 | 350 | allocator_wait(ca, ca->set->gc_mark_valid && |
2531d9ee | 351 | !ca->invalidate_needs_gc); |
86b26b82 | 352 | invalidate_buckets(ca); |
cafe5635 | 353 | |
86b26b82 KO |
354 | /* |
355 | * Now, we write their new gens to disk so we can start writing | |
356 | * new stuff to them: | |
357 | */ | |
358 | allocator_wait(ca, !atomic_read(&ca->set->prio_blocked)); | |
2531d9ee KO |
359 | if (CACHE_SYNC(&ca->set->sb)) { |
360 | /* | |
361 | * This could deadlock if an allocation with a btree | |
362 | * node locked ever blocked - having the btree node | |
363 | * locked would block garbage collection, but here we're | |
364 | * waiting on garbage collection before we invalidate | |
365 | * and free anything. | |
366 | * | |
367 | * But this should be safe since the btree code always | |
368 | * uses btree_check_reserve() before allocating now, and | |
369 | * if it fails it blocks without btree nodes locked. | |
370 | */ | |
371 | if (!fifo_full(&ca->free_inc)) | |
372 | goto retry_invalidate; | |
373 | ||
cafe5635 | 374 | bch_prio_write(ca); |
2531d9ee | 375 | } |
cafe5635 KO |
376 | } |
377 | } | |
378 | ||
2531d9ee KO |
379 | /* Allocation */ |
380 | ||
78365411 | 381 | long bch_bucket_alloc(struct cache *ca, unsigned reserve, bool wait) |
cafe5635 | 382 | { |
35fcd848 KO |
383 | DEFINE_WAIT(w); |
384 | struct bucket *b; | |
385 | long r; | |
386 | ||
387 | /* fastpath */ | |
78365411 KO |
388 | if (fifo_pop(&ca->free[RESERVE_NONE], r) || |
389 | fifo_pop(&ca->free[reserve], r)) | |
35fcd848 | 390 | goto out; |
35fcd848 | 391 | |
7159b1ad KO |
392 | if (!wait) { |
393 | trace_bcache_alloc_fail(ca, reserve); | |
35fcd848 | 394 | return -1; |
7159b1ad | 395 | } |
35fcd848 | 396 | |
78365411 | 397 | do { |
35fcd848 KO |
398 | prepare_to_wait(&ca->set->bucket_wait, &w, |
399 | TASK_UNINTERRUPTIBLE); | |
400 | ||
401 | mutex_unlock(&ca->set->bucket_lock); | |
402 | schedule(); | |
403 | mutex_lock(&ca->set->bucket_lock); | |
78365411 KO |
404 | } while (!fifo_pop(&ca->free[RESERVE_NONE], r) && |
405 | !fifo_pop(&ca->free[reserve], r)); | |
35fcd848 KO |
406 | |
407 | finish_wait(&ca->set->bucket_wait, &w); | |
408 | out: | |
119ba0f8 | 409 | wake_up_process(ca->alloc_thread); |
cafe5635 | 410 | |
7159b1ad KO |
411 | trace_bcache_alloc(ca, reserve); |
412 | ||
280481d0 | 413 | if (expensive_debug_checks(ca->set)) { |
cafe5635 KO |
414 | size_t iter; |
415 | long i; | |
78365411 | 416 | unsigned j; |
cafe5635 KO |
417 | |
418 | for (iter = 0; iter < prio_buckets(ca) * 2; iter++) | |
419 | BUG_ON(ca->prio_buckets[iter] == (uint64_t) r); | |
420 | ||
78365411 KO |
421 | for (j = 0; j < RESERVE_NR; j++) |
422 | fifo_for_each(i, &ca->free[j], iter) | |
423 | BUG_ON(i == r); | |
cafe5635 KO |
424 | fifo_for_each(i, &ca->free_inc, iter) |
425 | BUG_ON(i == r); | |
cafe5635 | 426 | } |
280481d0 | 427 | |
35fcd848 | 428 | b = ca->buckets + r; |
cafe5635 | 429 | |
35fcd848 | 430 | BUG_ON(atomic_read(&b->pin) != 1); |
cafe5635 | 431 | |
35fcd848 | 432 | SET_GC_SECTORS_USED(b, ca->sb.bucket_size); |
cafe5635 | 433 | |
78365411 | 434 | if (reserve <= RESERVE_PRIO) { |
35fcd848 | 435 | SET_GC_MARK(b, GC_MARK_METADATA); |
981aa8c0 | 436 | SET_GC_MOVE(b, 0); |
35fcd848 KO |
437 | b->prio = BTREE_PRIO; |
438 | } else { | |
439 | SET_GC_MARK(b, GC_MARK_RECLAIMABLE); | |
981aa8c0 | 440 | SET_GC_MOVE(b, 0); |
35fcd848 | 441 | b->prio = INITIAL_PRIO; |
cafe5635 KO |
442 | } |
443 | ||
35fcd848 | 444 | return r; |
cafe5635 KO |
445 | } |
446 | ||
2531d9ee KO |
447 | void __bch_bucket_free(struct cache *ca, struct bucket *b) |
448 | { | |
449 | SET_GC_MARK(b, 0); | |
450 | SET_GC_SECTORS_USED(b, 0); | |
451 | } | |
452 | ||
cafe5635 KO |
453 | void bch_bucket_free(struct cache_set *c, struct bkey *k) |
454 | { | |
455 | unsigned i; | |
456 | ||
2531d9ee KO |
457 | for (i = 0; i < KEY_PTRS(k); i++) |
458 | __bch_bucket_free(PTR_CACHE(c, k, i), | |
459 | PTR_BUCKET(c, k, i)); | |
cafe5635 KO |
460 | } |
461 | ||
78365411 | 462 | int __bch_bucket_alloc_set(struct cache_set *c, unsigned reserve, |
35fcd848 | 463 | struct bkey *k, int n, bool wait) |
cafe5635 KO |
464 | { |
465 | int i; | |
466 | ||
467 | lockdep_assert_held(&c->bucket_lock); | |
468 | BUG_ON(!n || n > c->caches_loaded || n > 8); | |
469 | ||
470 | bkey_init(k); | |
471 | ||
472 | /* sort by free space/prio of oldest data in caches */ | |
473 | ||
474 | for (i = 0; i < n; i++) { | |
475 | struct cache *ca = c->cache_by_alloc[i]; | |
78365411 | 476 | long b = bch_bucket_alloc(ca, reserve, wait); |
cafe5635 KO |
477 | |
478 | if (b == -1) | |
479 | goto err; | |
480 | ||
481 | k->ptr[i] = PTR(ca->buckets[b].gen, | |
482 | bucket_to_sector(c, b), | |
483 | ca->sb.nr_this_dev); | |
484 | ||
485 | SET_KEY_PTRS(k, i + 1); | |
486 | } | |
487 | ||
488 | return 0; | |
489 | err: | |
490 | bch_bucket_free(c, k); | |
3a3b6a4e | 491 | bkey_put(c, k); |
cafe5635 KO |
492 | return -1; |
493 | } | |
494 | ||
78365411 | 495 | int bch_bucket_alloc_set(struct cache_set *c, unsigned reserve, |
35fcd848 | 496 | struct bkey *k, int n, bool wait) |
cafe5635 KO |
497 | { |
498 | int ret; | |
499 | mutex_lock(&c->bucket_lock); | |
78365411 | 500 | ret = __bch_bucket_alloc_set(c, reserve, k, n, wait); |
cafe5635 KO |
501 | mutex_unlock(&c->bucket_lock); |
502 | return ret; | |
503 | } | |
504 | ||
2599b53b KO |
505 | /* Sector allocator */ |
506 | ||
507 | struct open_bucket { | |
508 | struct list_head list; | |
509 | unsigned last_write_point; | |
510 | unsigned sectors_free; | |
511 | BKEY_PADDED(key); | |
512 | }; | |
513 | ||
514 | /* | |
515 | * We keep multiple buckets open for writes, and try to segregate different | |
516 | * write streams for better cache utilization: first we look for a bucket where | |
517 | * the last write to it was sequential with the current write, and failing that | |
518 | * we look for a bucket that was last used by the same task. | |
519 | * | |
520 | * The ideas is if you've got multiple tasks pulling data into the cache at the | |
521 | * same time, you'll get better cache utilization if you try to segregate their | |
522 | * data and preserve locality. | |
523 | * | |
524 | * For example, say you've starting Firefox at the same time you're copying a | |
525 | * bunch of files. Firefox will likely end up being fairly hot and stay in the | |
526 | * cache awhile, but the data you copied might not be; if you wrote all that | |
527 | * data to the same buckets it'd get invalidated at the same time. | |
528 | * | |
529 | * Both of those tasks will be doing fairly random IO so we can't rely on | |
530 | * detecting sequential IO to segregate their data, but going off of the task | |
531 | * should be a sane heuristic. | |
532 | */ | |
533 | static struct open_bucket *pick_data_bucket(struct cache_set *c, | |
534 | const struct bkey *search, | |
535 | unsigned write_point, | |
536 | struct bkey *alloc) | |
537 | { | |
538 | struct open_bucket *ret, *ret_task = NULL; | |
539 | ||
540 | list_for_each_entry_reverse(ret, &c->data_buckets, list) | |
541 | if (!bkey_cmp(&ret->key, search)) | |
542 | goto found; | |
543 | else if (ret->last_write_point == write_point) | |
544 | ret_task = ret; | |
545 | ||
546 | ret = ret_task ?: list_first_entry(&c->data_buckets, | |
547 | struct open_bucket, list); | |
548 | found: | |
549 | if (!ret->sectors_free && KEY_PTRS(alloc)) { | |
550 | ret->sectors_free = c->sb.bucket_size; | |
551 | bkey_copy(&ret->key, alloc); | |
552 | bkey_init(alloc); | |
553 | } | |
554 | ||
555 | if (!ret->sectors_free) | |
556 | ret = NULL; | |
557 | ||
558 | return ret; | |
559 | } | |
560 | ||
561 | /* | |
562 | * Allocates some space in the cache to write to, and k to point to the newly | |
563 | * allocated space, and updates KEY_SIZE(k) and KEY_OFFSET(k) (to point to the | |
564 | * end of the newly allocated space). | |
565 | * | |
566 | * May allocate fewer sectors than @sectors, KEY_SIZE(k) indicates how many | |
567 | * sectors were actually allocated. | |
568 | * | |
569 | * If s->writeback is true, will not fail. | |
570 | */ | |
571 | bool bch_alloc_sectors(struct cache_set *c, struct bkey *k, unsigned sectors, | |
572 | unsigned write_point, unsigned write_prio, bool wait) | |
573 | { | |
574 | struct open_bucket *b; | |
575 | BKEY_PADDED(key) alloc; | |
576 | unsigned i; | |
577 | ||
578 | /* | |
579 | * We might have to allocate a new bucket, which we can't do with a | |
580 | * spinlock held. So if we have to allocate, we drop the lock, allocate | |
581 | * and then retry. KEY_PTRS() indicates whether alloc points to | |
582 | * allocated bucket(s). | |
583 | */ | |
584 | ||
585 | bkey_init(&alloc.key); | |
586 | spin_lock(&c->data_bucket_lock); | |
587 | ||
588 | while (!(b = pick_data_bucket(c, k, write_point, &alloc.key))) { | |
589 | unsigned watermark = write_prio | |
78365411 KO |
590 | ? RESERVE_MOVINGGC |
591 | : RESERVE_NONE; | |
2599b53b KO |
592 | |
593 | spin_unlock(&c->data_bucket_lock); | |
594 | ||
595 | if (bch_bucket_alloc_set(c, watermark, &alloc.key, 1, wait)) | |
596 | return false; | |
597 | ||
598 | spin_lock(&c->data_bucket_lock); | |
599 | } | |
600 | ||
601 | /* | |
602 | * If we had to allocate, we might race and not need to allocate the | |
603 | * second time we call find_data_bucket(). If we allocated a bucket but | |
604 | * didn't use it, drop the refcount bch_bucket_alloc_set() took: | |
605 | */ | |
606 | if (KEY_PTRS(&alloc.key)) | |
3a3b6a4e | 607 | bkey_put(c, &alloc.key); |
2599b53b KO |
608 | |
609 | for (i = 0; i < KEY_PTRS(&b->key); i++) | |
610 | EBUG_ON(ptr_stale(c, &b->key, i)); | |
611 | ||
612 | /* Set up the pointer to the space we're allocating: */ | |
613 | ||
614 | for (i = 0; i < KEY_PTRS(&b->key); i++) | |
615 | k->ptr[i] = b->key.ptr[i]; | |
616 | ||
617 | sectors = min(sectors, b->sectors_free); | |
618 | ||
619 | SET_KEY_OFFSET(k, KEY_OFFSET(k) + sectors); | |
620 | SET_KEY_SIZE(k, sectors); | |
621 | SET_KEY_PTRS(k, KEY_PTRS(&b->key)); | |
622 | ||
623 | /* | |
624 | * Move b to the end of the lru, and keep track of what this bucket was | |
625 | * last used for: | |
626 | */ | |
627 | list_move_tail(&b->list, &c->data_buckets); | |
628 | bkey_copy_key(&b->key, k); | |
629 | b->last_write_point = write_point; | |
630 | ||
631 | b->sectors_free -= sectors; | |
632 | ||
633 | for (i = 0; i < KEY_PTRS(&b->key); i++) { | |
634 | SET_PTR_OFFSET(&b->key, i, PTR_OFFSET(&b->key, i) + sectors); | |
635 | ||
636 | atomic_long_add(sectors, | |
637 | &PTR_CACHE(c, &b->key, i)->sectors_written); | |
638 | } | |
639 | ||
640 | if (b->sectors_free < c->sb.block_size) | |
641 | b->sectors_free = 0; | |
642 | ||
643 | /* | |
644 | * k takes refcounts on the buckets it points to until it's inserted | |
645 | * into the btree, but if we're done with this bucket we just transfer | |
646 | * get_data_bucket()'s refcount. | |
647 | */ | |
648 | if (b->sectors_free) | |
649 | for (i = 0; i < KEY_PTRS(&b->key); i++) | |
650 | atomic_inc(&PTR_BUCKET(c, &b->key, i)->pin); | |
651 | ||
652 | spin_unlock(&c->data_bucket_lock); | |
653 | return true; | |
654 | } | |
655 | ||
cafe5635 KO |
656 | /* Init */ |
657 | ||
2599b53b KO |
658 | void bch_open_buckets_free(struct cache_set *c) |
659 | { | |
660 | struct open_bucket *b; | |
661 | ||
662 | while (!list_empty(&c->data_buckets)) { | |
663 | b = list_first_entry(&c->data_buckets, | |
664 | struct open_bucket, list); | |
665 | list_del(&b->list); | |
666 | kfree(b); | |
667 | } | |
668 | } | |
669 | ||
670 | int bch_open_buckets_alloc(struct cache_set *c) | |
671 | { | |
672 | int i; | |
673 | ||
674 | spin_lock_init(&c->data_bucket_lock); | |
675 | ||
676 | for (i = 0; i < 6; i++) { | |
677 | struct open_bucket *b = kzalloc(sizeof(*b), GFP_KERNEL); | |
678 | if (!b) | |
679 | return -ENOMEM; | |
680 | ||
681 | list_add(&b->list, &c->data_buckets); | |
682 | } | |
683 | ||
684 | return 0; | |
685 | } | |
686 | ||
119ba0f8 KO |
687 | int bch_cache_allocator_start(struct cache *ca) |
688 | { | |
79826c35 KO |
689 | struct task_struct *k = kthread_run(bch_allocator_thread, |
690 | ca, "bcache_allocator"); | |
691 | if (IS_ERR(k)) | |
692 | return PTR_ERR(k); | |
119ba0f8 | 693 | |
79826c35 | 694 | ca->alloc_thread = k; |
119ba0f8 KO |
695 | return 0; |
696 | } |