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f2836352 JT |
1 | /* |
2 | * Copyright (C) 2012 Red Hat. All rights reserved. | |
3 | * | |
4 | * This file is released under the GPL. | |
5 | */ | |
6 | ||
7 | #include "dm-cache-policy.h" | |
8 | #include "dm.h" | |
9 | ||
10 | #include <linux/hash.h> | |
11 | #include <linux/module.h> | |
12 | #include <linux/mutex.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/vmalloc.h> | |
15 | ||
16 | #define DM_MSG_PREFIX "cache-policy-mq" | |
f2836352 JT |
17 | |
18 | static struct kmem_cache *mq_entry_cache; | |
19 | ||
20 | /*----------------------------------------------------------------*/ | |
21 | ||
22 | static unsigned next_power(unsigned n, unsigned min) | |
23 | { | |
24 | return roundup_pow_of_two(max(n, min)); | |
25 | } | |
26 | ||
27 | /*----------------------------------------------------------------*/ | |
28 | ||
f2836352 JT |
29 | /* |
30 | * Large, sequential ios are probably better left on the origin device since | |
31 | * spindles tend to have good bandwidth. | |
32 | * | |
33 | * The io_tracker tries to spot when the io is in one of these sequential | |
34 | * modes. | |
35 | * | |
36 | * Two thresholds to switch between random and sequential io mode are defaulting | |
37 | * as follows and can be adjusted via the constructor and message interfaces. | |
38 | */ | |
39 | #define RANDOM_THRESHOLD_DEFAULT 4 | |
40 | #define SEQUENTIAL_THRESHOLD_DEFAULT 512 | |
41 | ||
42 | enum io_pattern { | |
43 | PATTERN_SEQUENTIAL, | |
44 | PATTERN_RANDOM | |
45 | }; | |
46 | ||
47 | struct io_tracker { | |
48 | enum io_pattern pattern; | |
49 | ||
50 | unsigned nr_seq_samples; | |
51 | unsigned nr_rand_samples; | |
52 | unsigned thresholds[2]; | |
53 | ||
54 | dm_oblock_t last_end_oblock; | |
55 | }; | |
56 | ||
57 | static void iot_init(struct io_tracker *t, | |
58 | int sequential_threshold, int random_threshold) | |
59 | { | |
60 | t->pattern = PATTERN_RANDOM; | |
61 | t->nr_seq_samples = 0; | |
62 | t->nr_rand_samples = 0; | |
63 | t->last_end_oblock = 0; | |
64 | t->thresholds[PATTERN_RANDOM] = random_threshold; | |
65 | t->thresholds[PATTERN_SEQUENTIAL] = sequential_threshold; | |
66 | } | |
67 | ||
68 | static enum io_pattern iot_pattern(struct io_tracker *t) | |
69 | { | |
70 | return t->pattern; | |
71 | } | |
72 | ||
73 | static void iot_update_stats(struct io_tracker *t, struct bio *bio) | |
74 | { | |
4f024f37 | 75 | if (bio->bi_iter.bi_sector == from_oblock(t->last_end_oblock) + 1) |
f2836352 JT |
76 | t->nr_seq_samples++; |
77 | else { | |
78 | /* | |
79 | * Just one non-sequential IO is enough to reset the | |
80 | * counters. | |
81 | */ | |
82 | if (t->nr_seq_samples) { | |
83 | t->nr_seq_samples = 0; | |
84 | t->nr_rand_samples = 0; | |
85 | } | |
86 | ||
87 | t->nr_rand_samples++; | |
88 | } | |
89 | ||
4f024f37 | 90 | t->last_end_oblock = to_oblock(bio_end_sector(bio) - 1); |
f2836352 JT |
91 | } |
92 | ||
93 | static void iot_check_for_pattern_switch(struct io_tracker *t) | |
94 | { | |
95 | switch (t->pattern) { | |
96 | case PATTERN_SEQUENTIAL: | |
97 | if (t->nr_rand_samples >= t->thresholds[PATTERN_RANDOM]) { | |
98 | t->pattern = PATTERN_RANDOM; | |
99 | t->nr_seq_samples = t->nr_rand_samples = 0; | |
100 | } | |
101 | break; | |
102 | ||
103 | case PATTERN_RANDOM: | |
104 | if (t->nr_seq_samples >= t->thresholds[PATTERN_SEQUENTIAL]) { | |
105 | t->pattern = PATTERN_SEQUENTIAL; | |
106 | t->nr_seq_samples = t->nr_rand_samples = 0; | |
107 | } | |
108 | break; | |
109 | } | |
110 | } | |
111 | ||
112 | static void iot_examine_bio(struct io_tracker *t, struct bio *bio) | |
113 | { | |
114 | iot_update_stats(t, bio); | |
115 | iot_check_for_pattern_switch(t); | |
116 | } | |
117 | ||
118 | /*----------------------------------------------------------------*/ | |
119 | ||
120 | ||
121 | /* | |
122 | * This queue is divided up into different levels. Allowing us to push | |
123 | * entries to the back of any of the levels. Think of it as a partially | |
124 | * sorted queue. | |
125 | */ | |
126 | #define NR_QUEUE_LEVELS 16u | |
127 | ||
128 | struct queue { | |
129 | struct list_head qs[NR_QUEUE_LEVELS]; | |
130 | }; | |
131 | ||
132 | static void queue_init(struct queue *q) | |
133 | { | |
134 | unsigned i; | |
135 | ||
136 | for (i = 0; i < NR_QUEUE_LEVELS; i++) | |
137 | INIT_LIST_HEAD(q->qs + i); | |
138 | } | |
139 | ||
c86c3070 JT |
140 | /* |
141 | * Checks to see if the queue is empty. | |
142 | * FIXME: reduce cpu usage. | |
143 | */ | |
144 | static bool queue_empty(struct queue *q) | |
145 | { | |
146 | unsigned i; | |
147 | ||
148 | for (i = 0; i < NR_QUEUE_LEVELS; i++) | |
149 | if (!list_empty(q->qs + i)) | |
150 | return false; | |
151 | ||
152 | return true; | |
153 | } | |
154 | ||
f2836352 JT |
155 | /* |
156 | * Insert an entry to the back of the given level. | |
157 | */ | |
158 | static void queue_push(struct queue *q, unsigned level, struct list_head *elt) | |
159 | { | |
160 | list_add_tail(elt, q->qs + level); | |
161 | } | |
162 | ||
163 | static void queue_remove(struct list_head *elt) | |
164 | { | |
165 | list_del(elt); | |
166 | } | |
167 | ||
168 | /* | |
169 | * Shifts all regions down one level. This has no effect on the order of | |
170 | * the queue. | |
171 | */ | |
172 | static void queue_shift_down(struct queue *q) | |
173 | { | |
174 | unsigned level; | |
175 | ||
176 | for (level = 1; level < NR_QUEUE_LEVELS; level++) | |
177 | list_splice_init(q->qs + level, q->qs + level - 1); | |
178 | } | |
179 | ||
180 | /* | |
181 | * Gives us the oldest entry of the lowest popoulated level. If the first | |
182 | * level is emptied then we shift down one level. | |
183 | */ | |
b155aa0e | 184 | static struct list_head *queue_peek(struct queue *q) |
f2836352 JT |
185 | { |
186 | unsigned level; | |
f2836352 JT |
187 | |
188 | for (level = 0; level < NR_QUEUE_LEVELS; level++) | |
b155aa0e JT |
189 | if (!list_empty(q->qs + level)) |
190 | return q->qs[level].next; | |
f2836352 | 191 | |
b155aa0e JT |
192 | return NULL; |
193 | } | |
f2836352 | 194 | |
b155aa0e JT |
195 | static struct list_head *queue_pop(struct queue *q) |
196 | { | |
197 | struct list_head *r = queue_peek(q); | |
f2836352 | 198 | |
b155aa0e JT |
199 | if (r) { |
200 | list_del(r); | |
201 | ||
202 | /* have we just emptied the bottom level? */ | |
203 | if (list_empty(q->qs)) | |
204 | queue_shift_down(q); | |
205 | } | |
206 | ||
207 | return r; | |
f2836352 JT |
208 | } |
209 | ||
210 | static struct list_head *list_pop(struct list_head *lh) | |
211 | { | |
212 | struct list_head *r = lh->next; | |
213 | ||
214 | BUG_ON(!r); | |
215 | list_del_init(r); | |
216 | ||
217 | return r; | |
218 | } | |
219 | ||
220 | /*----------------------------------------------------------------*/ | |
221 | ||
222 | /* | |
223 | * Describes a cache entry. Used in both the cache and the pre_cache. | |
224 | */ | |
225 | struct entry { | |
226 | struct hlist_node hlist; | |
227 | struct list_head list; | |
228 | dm_oblock_t oblock; | |
f2836352 JT |
229 | |
230 | /* | |
231 | * FIXME: pack these better | |
232 | */ | |
01911c19 | 233 | bool dirty:1; |
f2836352 JT |
234 | unsigned hit_count; |
235 | unsigned generation; | |
236 | unsigned tick; | |
237 | }; | |
238 | ||
633618e3 JT |
239 | /* |
240 | * Rather than storing the cblock in an entry, we allocate all entries in | |
241 | * an array, and infer the cblock from the entry position. | |
242 | * | |
243 | * Free entries are linked together into a list. | |
244 | */ | |
245 | struct entry_pool { | |
246 | struct entry *entries, *entries_end; | |
247 | struct list_head free; | |
248 | unsigned nr_allocated; | |
249 | }; | |
250 | ||
251 | static int epool_init(struct entry_pool *ep, unsigned nr_entries) | |
252 | { | |
253 | unsigned i; | |
254 | ||
255 | ep->entries = vzalloc(sizeof(struct entry) * nr_entries); | |
256 | if (!ep->entries) | |
257 | return -ENOMEM; | |
258 | ||
259 | ep->entries_end = ep->entries + nr_entries; | |
260 | ||
261 | INIT_LIST_HEAD(&ep->free); | |
262 | for (i = 0; i < nr_entries; i++) | |
263 | list_add(&ep->entries[i].list, &ep->free); | |
264 | ||
265 | ep->nr_allocated = 0; | |
266 | ||
267 | return 0; | |
268 | } | |
269 | ||
270 | static void epool_exit(struct entry_pool *ep) | |
271 | { | |
272 | vfree(ep->entries); | |
273 | } | |
274 | ||
275 | static struct entry *alloc_entry(struct entry_pool *ep) | |
276 | { | |
277 | struct entry *e; | |
278 | ||
279 | if (list_empty(&ep->free)) | |
280 | return NULL; | |
281 | ||
282 | e = list_entry(list_pop(&ep->free), struct entry, list); | |
283 | INIT_LIST_HEAD(&e->list); | |
284 | INIT_HLIST_NODE(&e->hlist); | |
285 | ep->nr_allocated++; | |
286 | ||
287 | return e; | |
288 | } | |
289 | ||
290 | /* | |
291 | * This assumes the cblock hasn't already been allocated. | |
292 | */ | |
293 | static struct entry *alloc_particular_entry(struct entry_pool *ep, dm_cblock_t cblock) | |
294 | { | |
295 | struct entry *e = ep->entries + from_cblock(cblock); | |
633618e3 | 296 | |
b8158051 | 297 | list_del_init(&e->list); |
633618e3 JT |
298 | INIT_HLIST_NODE(&e->hlist); |
299 | ep->nr_allocated++; | |
300 | ||
301 | return e; | |
302 | } | |
303 | ||
304 | static void free_entry(struct entry_pool *ep, struct entry *e) | |
305 | { | |
306 | BUG_ON(!ep->nr_allocated); | |
307 | ep->nr_allocated--; | |
308 | INIT_HLIST_NODE(&e->hlist); | |
309 | list_add(&e->list, &ep->free); | |
310 | } | |
311 | ||
532906aa JT |
312 | /* |
313 | * Returns NULL if the entry is free. | |
314 | */ | |
315 | static struct entry *epool_find(struct entry_pool *ep, dm_cblock_t cblock) | |
316 | { | |
317 | struct entry *e = ep->entries + from_cblock(cblock); | |
7b6b2bc9 | 318 | return !hlist_unhashed(&e->hlist) ? e : NULL; |
532906aa JT |
319 | } |
320 | ||
633618e3 JT |
321 | static bool epool_empty(struct entry_pool *ep) |
322 | { | |
323 | return list_empty(&ep->free); | |
324 | } | |
325 | ||
326 | static bool in_pool(struct entry_pool *ep, struct entry *e) | |
327 | { | |
328 | return e >= ep->entries && e < ep->entries_end; | |
329 | } | |
330 | ||
331 | static dm_cblock_t infer_cblock(struct entry_pool *ep, struct entry *e) | |
332 | { | |
333 | return to_cblock(e - ep->entries); | |
334 | } | |
335 | ||
336 | /*----------------------------------------------------------------*/ | |
337 | ||
f2836352 JT |
338 | struct mq_policy { |
339 | struct dm_cache_policy policy; | |
340 | ||
341 | /* protects everything */ | |
342 | struct mutex lock; | |
343 | dm_cblock_t cache_size; | |
344 | struct io_tracker tracker; | |
345 | ||
633618e3 JT |
346 | /* |
347 | * Entries come from two pools, one of pre-cache entries, and one | |
348 | * for the cache proper. | |
349 | */ | |
350 | struct entry_pool pre_cache_pool; | |
351 | struct entry_pool cache_pool; | |
352 | ||
f2836352 | 353 | /* |
01911c19 JT |
354 | * We maintain three queues of entries. The cache proper, |
355 | * consisting of a clean and dirty queue, contains the currently | |
356 | * active mappings. Whereas the pre_cache tracks blocks that | |
357 | * are being hit frequently and potential candidates for promotion | |
358 | * to the cache. | |
f2836352 JT |
359 | */ |
360 | struct queue pre_cache; | |
01911c19 JT |
361 | struct queue cache_clean; |
362 | struct queue cache_dirty; | |
f2836352 JT |
363 | |
364 | /* | |
365 | * Keeps track of time, incremented by the core. We use this to | |
366 | * avoid attributing multiple hits within the same tick. | |
367 | * | |
368 | * Access to tick_protected should be done with the spin lock held. | |
369 | * It's copied to tick at the start of the map function (within the | |
370 | * mutex). | |
371 | */ | |
372 | spinlock_t tick_lock; | |
373 | unsigned tick_protected; | |
374 | unsigned tick; | |
375 | ||
376 | /* | |
377 | * A count of the number of times the map function has been called | |
378 | * and found an entry in the pre_cache or cache. Currently used to | |
379 | * calculate the generation. | |
380 | */ | |
381 | unsigned hit_count; | |
382 | ||
383 | /* | |
384 | * A generation is a longish period that is used to trigger some | |
385 | * book keeping effects. eg, decrementing hit counts on entries. | |
386 | * This is needed to allow the cache to evolve as io patterns | |
387 | * change. | |
388 | */ | |
389 | unsigned generation; | |
390 | unsigned generation_period; /* in lookups (will probably change) */ | |
391 | ||
78e03d69 JT |
392 | unsigned discard_promote_adjustment; |
393 | unsigned read_promote_adjustment; | |
394 | unsigned write_promote_adjustment; | |
395 | ||
f2836352 JT |
396 | /* |
397 | * The hash table allows us to quickly find an entry by origin | |
398 | * block. Both pre_cache and cache entries are in here. | |
399 | */ | |
400 | unsigned nr_buckets; | |
401 | dm_block_t hash_bits; | |
402 | struct hlist_head *table; | |
403 | }; | |
404 | ||
78e03d69 JT |
405 | #define DEFAULT_DISCARD_PROMOTE_ADJUSTMENT 1 |
406 | #define DEFAULT_READ_PROMOTE_ADJUSTMENT 4 | |
407 | #define DEFAULT_WRITE_PROMOTE_ADJUSTMENT 8 | |
b155aa0e | 408 | #define DISCOURAGE_DEMOTING_DIRTY_THRESHOLD 128 |
78e03d69 | 409 | |
f2836352 JT |
410 | /*----------------------------------------------------------------*/ |
411 | ||
412 | /* | |
413 | * Simple hash table implementation. Should replace with the standard hash | |
414 | * table that's making its way upstream. | |
415 | */ | |
416 | static void hash_insert(struct mq_policy *mq, struct entry *e) | |
417 | { | |
418 | unsigned h = hash_64(from_oblock(e->oblock), mq->hash_bits); | |
419 | ||
420 | hlist_add_head(&e->hlist, mq->table + h); | |
421 | } | |
422 | ||
423 | static struct entry *hash_lookup(struct mq_policy *mq, dm_oblock_t oblock) | |
424 | { | |
425 | unsigned h = hash_64(from_oblock(oblock), mq->hash_bits); | |
426 | struct hlist_head *bucket = mq->table + h; | |
427 | struct entry *e; | |
428 | ||
429 | hlist_for_each_entry(e, bucket, hlist) | |
430 | if (e->oblock == oblock) { | |
431 | hlist_del(&e->hlist); | |
432 | hlist_add_head(&e->hlist, bucket); | |
433 | return e; | |
434 | } | |
435 | ||
436 | return NULL; | |
437 | } | |
438 | ||
439 | static void hash_remove(struct entry *e) | |
440 | { | |
441 | hlist_del(&e->hlist); | |
442 | } | |
443 | ||
444 | /*----------------------------------------------------------------*/ | |
445 | ||
f2836352 JT |
446 | static bool any_free_cblocks(struct mq_policy *mq) |
447 | { | |
633618e3 | 448 | return !epool_empty(&mq->cache_pool); |
f2836352 JT |
449 | } |
450 | ||
c86c3070 JT |
451 | static bool any_clean_cblocks(struct mq_policy *mq) |
452 | { | |
453 | return !queue_empty(&mq->cache_clean); | |
454 | } | |
455 | ||
f2836352 JT |
456 | /*----------------------------------------------------------------*/ |
457 | ||
458 | /* | |
459 | * Now we get to the meat of the policy. This section deals with deciding | |
460 | * when to to add entries to the pre_cache and cache, and move between | |
461 | * them. | |
462 | */ | |
463 | ||
464 | /* | |
465 | * The queue level is based on the log2 of the hit count. | |
466 | */ | |
467 | static unsigned queue_level(struct entry *e) | |
468 | { | |
469 | return min((unsigned) ilog2(e->hit_count), NR_QUEUE_LEVELS - 1u); | |
470 | } | |
471 | ||
633618e3 JT |
472 | static bool in_cache(struct mq_policy *mq, struct entry *e) |
473 | { | |
474 | return in_pool(&mq->cache_pool, e); | |
475 | } | |
476 | ||
f2836352 JT |
477 | /* |
478 | * Inserts the entry into the pre_cache or the cache. Ensures the cache | |
633618e3 JT |
479 | * block is marked as allocated if necc. Inserts into the hash table. |
480 | * Sets the tick which records when the entry was last moved about. | |
f2836352 JT |
481 | */ |
482 | static void push(struct mq_policy *mq, struct entry *e) | |
483 | { | |
484 | e->tick = mq->tick; | |
485 | hash_insert(mq, e); | |
486 | ||
633618e3 | 487 | if (in_cache(mq, e)) |
01911c19 JT |
488 | queue_push(e->dirty ? &mq->cache_dirty : &mq->cache_clean, |
489 | queue_level(e), &e->list); | |
633618e3 | 490 | else |
f2836352 JT |
491 | queue_push(&mq->pre_cache, queue_level(e), &e->list); |
492 | } | |
493 | ||
494 | /* | |
495 | * Removes an entry from pre_cache or cache. Removes from the hash table. | |
f2836352 JT |
496 | */ |
497 | static void del(struct mq_policy *mq, struct entry *e) | |
498 | { | |
499 | queue_remove(&e->list); | |
500 | hash_remove(e); | |
f2836352 JT |
501 | } |
502 | ||
503 | /* | |
504 | * Like del, except it removes the first entry in the queue (ie. the least | |
505 | * recently used). | |
506 | */ | |
507 | static struct entry *pop(struct mq_policy *mq, struct queue *q) | |
508 | { | |
0184b44e JT |
509 | struct entry *e; |
510 | struct list_head *h = queue_pop(q); | |
f2836352 | 511 | |
0184b44e JT |
512 | if (!h) |
513 | return NULL; | |
f2836352 | 514 | |
0184b44e JT |
515 | e = container_of(h, struct entry, list); |
516 | hash_remove(e); | |
f2836352 JT |
517 | |
518 | return e; | |
519 | } | |
520 | ||
b155aa0e JT |
521 | static struct entry *peek(struct queue *q) |
522 | { | |
523 | struct list_head *h = queue_peek(q); | |
524 | return h ? container_of(h, struct entry, list) : NULL; | |
525 | } | |
526 | ||
f2836352 JT |
527 | /* |
528 | * Has this entry already been updated? | |
529 | */ | |
530 | static bool updated_this_tick(struct mq_policy *mq, struct entry *e) | |
531 | { | |
532 | return mq->tick == e->tick; | |
533 | } | |
534 | ||
535 | /* | |
536 | * The promotion threshold is adjusted every generation. As are the counts | |
537 | * of the entries. | |
538 | * | |
539 | * At the moment the threshold is taken by averaging the hit counts of some | |
01911c19 JT |
540 | * of the entries in the cache (the first 20 entries across all levels in |
541 | * ascending order, giving preference to the clean entries at each level). | |
f2836352 JT |
542 | * |
543 | * We can be much cleverer than this though. For example, each promotion | |
544 | * could bump up the threshold helping to prevent churn. Much more to do | |
545 | * here. | |
546 | */ | |
547 | ||
548 | #define MAX_TO_AVERAGE 20 | |
549 | ||
550 | static void check_generation(struct mq_policy *mq) | |
551 | { | |
552 | unsigned total = 0, nr = 0, count = 0, level; | |
553 | struct list_head *head; | |
554 | struct entry *e; | |
555 | ||
633618e3 | 556 | if ((mq->hit_count >= mq->generation_period) && (epool_empty(&mq->cache_pool))) { |
f2836352 JT |
557 | mq->hit_count = 0; |
558 | mq->generation++; | |
559 | ||
560 | for (level = 0; level < NR_QUEUE_LEVELS && count < MAX_TO_AVERAGE; level++) { | |
01911c19 JT |
561 | head = mq->cache_clean.qs + level; |
562 | list_for_each_entry(e, head, list) { | |
563 | nr++; | |
564 | total += e->hit_count; | |
565 | ||
566 | if (++count >= MAX_TO_AVERAGE) | |
567 | break; | |
568 | } | |
569 | ||
570 | head = mq->cache_dirty.qs + level; | |
f2836352 JT |
571 | list_for_each_entry(e, head, list) { |
572 | nr++; | |
573 | total += e->hit_count; | |
574 | ||
575 | if (++count >= MAX_TO_AVERAGE) | |
576 | break; | |
577 | } | |
578 | } | |
f2836352 JT |
579 | } |
580 | } | |
581 | ||
582 | /* | |
583 | * Whenever we use an entry we bump up it's hit counter, and push it to the | |
584 | * back to it's current level. | |
585 | */ | |
586 | static void requeue_and_update_tick(struct mq_policy *mq, struct entry *e) | |
587 | { | |
588 | if (updated_this_tick(mq, e)) | |
589 | return; | |
590 | ||
591 | e->hit_count++; | |
592 | mq->hit_count++; | |
593 | check_generation(mq); | |
594 | ||
595 | /* generation adjustment, to stop the counts increasing forever. */ | |
596 | /* FIXME: divide? */ | |
597 | /* e->hit_count -= min(e->hit_count - 1, mq->generation - e->generation); */ | |
598 | e->generation = mq->generation; | |
599 | ||
600 | del(mq, e); | |
601 | push(mq, e); | |
602 | } | |
603 | ||
604 | /* | |
605 | * Demote the least recently used entry from the cache to the pre_cache. | |
606 | * Returns the new cache entry to use, and the old origin block it was | |
607 | * mapped to. | |
608 | * | |
609 | * We drop the hit count on the demoted entry back to 1 to stop it bouncing | |
610 | * straight back into the cache if it's subsequently hit. There are | |
611 | * various options here, and more experimentation would be good: | |
612 | * | |
613 | * - just forget about the demoted entry completely (ie. don't insert it | |
614 | into the pre_cache). | |
615 | * - divide the hit count rather that setting to some hard coded value. | |
616 | * - set the hit count to a hard coded value other than 1, eg, is it better | |
617 | * if it goes in at level 2? | |
618 | */ | |
633618e3 | 619 | static int demote_cblock(struct mq_policy *mq, dm_oblock_t *oblock) |
f2836352 | 620 | { |
01911c19 | 621 | struct entry *demoted = pop(mq, &mq->cache_clean); |
f2836352 | 622 | |
01911c19 JT |
623 | if (!demoted) |
624 | /* | |
625 | * We could get a block from mq->cache_dirty, but that | |
626 | * would add extra latency to the triggering bio as it | |
627 | * waits for the writeback. Better to not promote this | |
628 | * time and hope there's a clean block next time this block | |
629 | * is hit. | |
630 | */ | |
631 | return -ENOSPC; | |
632 | ||
f2836352 | 633 | *oblock = demoted->oblock; |
633618e3 JT |
634 | free_entry(&mq->cache_pool, demoted); |
635 | ||
636 | /* | |
637 | * We used to put the demoted block into the pre-cache, but I think | |
638 | * it's simpler to just let it work it's way up from zero again. | |
639 | * Stops blocks flickering in and out of the cache. | |
640 | */ | |
f2836352 | 641 | |
01911c19 | 642 | return 0; |
f2836352 JT |
643 | } |
644 | ||
b155aa0e JT |
645 | /* |
646 | * Entries in the pre_cache whose hit count passes the promotion | |
647 | * threshold move to the cache proper. Working out the correct | |
648 | * value for the promotion_threshold is crucial to this policy. | |
649 | */ | |
650 | static unsigned promote_threshold(struct mq_policy *mq) | |
651 | { | |
652 | struct entry *e; | |
653 | ||
654 | if (any_free_cblocks(mq)) | |
655 | return 0; | |
656 | ||
657 | e = peek(&mq->cache_clean); | |
658 | if (e) | |
659 | return e->hit_count; | |
660 | ||
661 | e = peek(&mq->cache_dirty); | |
662 | if (e) | |
663 | return e->hit_count + DISCOURAGE_DEMOTING_DIRTY_THRESHOLD; | |
664 | ||
665 | /* This should never happen */ | |
666 | return 0; | |
667 | } | |
668 | ||
f2836352 JT |
669 | /* |
670 | * We modify the basic promotion_threshold depending on the specific io. | |
671 | * | |
672 | * If the origin block has been discarded then there's no cost to copy it | |
673 | * to the cache. | |
674 | * | |
675 | * We bias towards reads, since they can be demoted at no cost if they | |
676 | * haven't been dirtied. | |
677 | */ | |
f2836352 JT |
678 | static unsigned adjusted_promote_threshold(struct mq_policy *mq, |
679 | bool discarded_oblock, int data_dir) | |
680 | { | |
c86c3070 | 681 | if (data_dir == READ) |
b155aa0e | 682 | return promote_threshold(mq) + mq->read_promote_adjustment; |
c86c3070 JT |
683 | |
684 | if (discarded_oblock && (any_free_cblocks(mq) || any_clean_cblocks(mq))) { | |
f2836352 JT |
685 | /* |
686 | * We don't need to do any copying at all, so give this a | |
c86c3070 | 687 | * very low threshold. |
f2836352 | 688 | */ |
78e03d69 | 689 | return mq->discard_promote_adjustment; |
c86c3070 | 690 | } |
f2836352 | 691 | |
b155aa0e | 692 | return promote_threshold(mq) + mq->write_promote_adjustment; |
f2836352 JT |
693 | } |
694 | ||
695 | static bool should_promote(struct mq_policy *mq, struct entry *e, | |
696 | bool discarded_oblock, int data_dir) | |
697 | { | |
698 | return e->hit_count >= | |
699 | adjusted_promote_threshold(mq, discarded_oblock, data_dir); | |
700 | } | |
701 | ||
702 | static int cache_entry_found(struct mq_policy *mq, | |
703 | struct entry *e, | |
704 | struct policy_result *result) | |
705 | { | |
706 | requeue_and_update_tick(mq, e); | |
707 | ||
633618e3 | 708 | if (in_cache(mq, e)) { |
f2836352 | 709 | result->op = POLICY_HIT; |
633618e3 | 710 | result->cblock = infer_cblock(&mq->cache_pool, e); |
f2836352 JT |
711 | } |
712 | ||
713 | return 0; | |
714 | } | |
715 | ||
716 | /* | |
0184b44e | 717 | * Moves an entry from the pre_cache to the cache. The main work is |
f2836352 JT |
718 | * finding which cache block to use. |
719 | */ | |
720 | static int pre_cache_to_cache(struct mq_policy *mq, struct entry *e, | |
721 | struct policy_result *result) | |
722 | { | |
01911c19 | 723 | int r; |
633618e3 | 724 | struct entry *new_e; |
f2836352 | 725 | |
633618e3 JT |
726 | /* Ensure there's a free cblock in the cache */ |
727 | if (epool_empty(&mq->cache_pool)) { | |
f2836352 | 728 | result->op = POLICY_REPLACE; |
633618e3 | 729 | r = demote_cblock(mq, &result->old_oblock); |
01911c19 JT |
730 | if (r) { |
731 | result->op = POLICY_MISS; | |
732 | return 0; | |
733 | } | |
f2836352 JT |
734 | } else |
735 | result->op = POLICY_NEW; | |
736 | ||
633618e3 JT |
737 | new_e = alloc_entry(&mq->cache_pool); |
738 | BUG_ON(!new_e); | |
739 | ||
740 | new_e->oblock = e->oblock; | |
741 | new_e->dirty = false; | |
742 | new_e->hit_count = e->hit_count; | |
743 | new_e->generation = e->generation; | |
744 | new_e->tick = e->tick; | |
f2836352 JT |
745 | |
746 | del(mq, e); | |
633618e3 JT |
747 | free_entry(&mq->pre_cache_pool, e); |
748 | push(mq, new_e); | |
749 | ||
750 | result->cblock = infer_cblock(&mq->cache_pool, new_e); | |
f2836352 JT |
751 | |
752 | return 0; | |
753 | } | |
754 | ||
755 | static int pre_cache_entry_found(struct mq_policy *mq, struct entry *e, | |
756 | bool can_migrate, bool discarded_oblock, | |
757 | int data_dir, struct policy_result *result) | |
758 | { | |
759 | int r = 0; | |
760 | bool updated = updated_this_tick(mq, e); | |
761 | ||
f2836352 | 762 | if ((!discarded_oblock && updated) || |
af95e7a6 JT |
763 | !should_promote(mq, e, discarded_oblock, data_dir)) { |
764 | requeue_and_update_tick(mq, e); | |
f2836352 | 765 | result->op = POLICY_MISS; |
af95e7a6 JT |
766 | |
767 | } else if (!can_migrate) | |
f2836352 | 768 | r = -EWOULDBLOCK; |
af95e7a6 JT |
769 | |
770 | else { | |
771 | requeue_and_update_tick(mq, e); | |
f2836352 | 772 | r = pre_cache_to_cache(mq, e, result); |
af95e7a6 | 773 | } |
f2836352 JT |
774 | |
775 | return r; | |
776 | } | |
777 | ||
778 | static void insert_in_pre_cache(struct mq_policy *mq, | |
779 | dm_oblock_t oblock) | |
780 | { | |
633618e3 | 781 | struct entry *e = alloc_entry(&mq->pre_cache_pool); |
f2836352 JT |
782 | |
783 | if (!e) | |
784 | /* | |
785 | * There's no spare entry structure, so we grab the least | |
786 | * used one from the pre_cache. | |
787 | */ | |
788 | e = pop(mq, &mq->pre_cache); | |
789 | ||
790 | if (unlikely(!e)) { | |
791 | DMWARN("couldn't pop from pre cache"); | |
792 | return; | |
793 | } | |
794 | ||
633618e3 JT |
795 | e->dirty = false; |
796 | e->oblock = oblock; | |
797 | e->hit_count = 1; | |
798 | e->generation = mq->generation; | |
799 | push(mq, e); | |
f2836352 JT |
800 | } |
801 | ||
802 | static void insert_in_cache(struct mq_policy *mq, dm_oblock_t oblock, | |
803 | struct policy_result *result) | |
804 | { | |
c86c3070 | 805 | int r; |
f2836352 | 806 | struct entry *e; |
f2836352 | 807 | |
633618e3 JT |
808 | if (epool_empty(&mq->cache_pool)) { |
809 | result->op = POLICY_REPLACE; | |
810 | r = demote_cblock(mq, &result->old_oblock); | |
c86c3070 JT |
811 | if (unlikely(r)) { |
812 | result->op = POLICY_MISS; | |
813 | insert_in_pre_cache(mq, oblock); | |
814 | return; | |
815 | } | |
f2836352 | 816 | |
c86c3070 JT |
817 | /* |
818 | * This will always succeed, since we've just demoted. | |
819 | */ | |
633618e3 JT |
820 | e = alloc_entry(&mq->cache_pool); |
821 | BUG_ON(!e); | |
c86c3070 JT |
822 | |
823 | } else { | |
633618e3 | 824 | e = alloc_entry(&mq->cache_pool); |
c86c3070 | 825 | result->op = POLICY_NEW; |
f2836352 JT |
826 | } |
827 | ||
828 | e->oblock = oblock; | |
01911c19 | 829 | e->dirty = false; |
f2836352 JT |
830 | e->hit_count = 1; |
831 | e->generation = mq->generation; | |
832 | push(mq, e); | |
833 | ||
633618e3 | 834 | result->cblock = infer_cblock(&mq->cache_pool, e); |
f2836352 JT |
835 | } |
836 | ||
837 | static int no_entry_found(struct mq_policy *mq, dm_oblock_t oblock, | |
838 | bool can_migrate, bool discarded_oblock, | |
839 | int data_dir, struct policy_result *result) | |
840 | { | |
78e03d69 | 841 | if (adjusted_promote_threshold(mq, discarded_oblock, data_dir) <= 1) { |
f2836352 JT |
842 | if (can_migrate) |
843 | insert_in_cache(mq, oblock, result); | |
844 | else | |
845 | return -EWOULDBLOCK; | |
846 | } else { | |
847 | insert_in_pre_cache(mq, oblock); | |
848 | result->op = POLICY_MISS; | |
849 | } | |
850 | ||
851 | return 0; | |
852 | } | |
853 | ||
854 | /* | |
855 | * Looks the oblock up in the hash table, then decides whether to put in | |
856 | * pre_cache, or cache etc. | |
857 | */ | |
858 | static int map(struct mq_policy *mq, dm_oblock_t oblock, | |
859 | bool can_migrate, bool discarded_oblock, | |
860 | int data_dir, struct policy_result *result) | |
861 | { | |
862 | int r = 0; | |
863 | struct entry *e = hash_lookup(mq, oblock); | |
864 | ||
633618e3 | 865 | if (e && in_cache(mq, e)) |
f2836352 | 866 | r = cache_entry_found(mq, e, result); |
633618e3 | 867 | |
f1afb36a MS |
868 | else if (mq->tracker.thresholds[PATTERN_SEQUENTIAL] && |
869 | iot_pattern(&mq->tracker) == PATTERN_SEQUENTIAL) | |
f2836352 | 870 | result->op = POLICY_MISS; |
633618e3 | 871 | |
f2836352 JT |
872 | else if (e) |
873 | r = pre_cache_entry_found(mq, e, can_migrate, discarded_oblock, | |
874 | data_dir, result); | |
633618e3 | 875 | |
f2836352 JT |
876 | else |
877 | r = no_entry_found(mq, oblock, can_migrate, discarded_oblock, | |
878 | data_dir, result); | |
879 | ||
880 | if (r == -EWOULDBLOCK) | |
881 | result->op = POLICY_MISS; | |
882 | ||
883 | return r; | |
884 | } | |
885 | ||
886 | /*----------------------------------------------------------------*/ | |
887 | ||
888 | /* | |
889 | * Public interface, via the policy struct. See dm-cache-policy.h for a | |
890 | * description of these. | |
891 | */ | |
892 | ||
893 | static struct mq_policy *to_mq_policy(struct dm_cache_policy *p) | |
894 | { | |
895 | return container_of(p, struct mq_policy, policy); | |
896 | } | |
897 | ||
898 | static void mq_destroy(struct dm_cache_policy *p) | |
899 | { | |
900 | struct mq_policy *mq = to_mq_policy(p); | |
901 | ||
14f398ca | 902 | vfree(mq->table); |
633618e3 JT |
903 | epool_exit(&mq->cache_pool); |
904 | epool_exit(&mq->pre_cache_pool); | |
f2836352 JT |
905 | kfree(mq); |
906 | } | |
907 | ||
908 | static void copy_tick(struct mq_policy *mq) | |
909 | { | |
910 | unsigned long flags; | |
911 | ||
912 | spin_lock_irqsave(&mq->tick_lock, flags); | |
913 | mq->tick = mq->tick_protected; | |
914 | spin_unlock_irqrestore(&mq->tick_lock, flags); | |
915 | } | |
916 | ||
917 | static int mq_map(struct dm_cache_policy *p, dm_oblock_t oblock, | |
918 | bool can_block, bool can_migrate, bool discarded_oblock, | |
919 | struct bio *bio, struct policy_result *result) | |
920 | { | |
921 | int r; | |
922 | struct mq_policy *mq = to_mq_policy(p); | |
923 | ||
924 | result->op = POLICY_MISS; | |
925 | ||
926 | if (can_block) | |
927 | mutex_lock(&mq->lock); | |
928 | else if (!mutex_trylock(&mq->lock)) | |
929 | return -EWOULDBLOCK; | |
930 | ||
931 | copy_tick(mq); | |
932 | ||
933 | iot_examine_bio(&mq->tracker, bio); | |
934 | r = map(mq, oblock, can_migrate, discarded_oblock, | |
935 | bio_data_dir(bio), result); | |
936 | ||
937 | mutex_unlock(&mq->lock); | |
938 | ||
939 | return r; | |
940 | } | |
941 | ||
942 | static int mq_lookup(struct dm_cache_policy *p, dm_oblock_t oblock, dm_cblock_t *cblock) | |
943 | { | |
944 | int r; | |
945 | struct mq_policy *mq = to_mq_policy(p); | |
946 | struct entry *e; | |
947 | ||
948 | if (!mutex_trylock(&mq->lock)) | |
949 | return -EWOULDBLOCK; | |
950 | ||
951 | e = hash_lookup(mq, oblock); | |
633618e3 JT |
952 | if (e && in_cache(mq, e)) { |
953 | *cblock = infer_cblock(&mq->cache_pool, e); | |
f2836352 JT |
954 | r = 0; |
955 | } else | |
956 | r = -ENOENT; | |
957 | ||
958 | mutex_unlock(&mq->lock); | |
959 | ||
960 | return r; | |
961 | } | |
962 | ||
633618e3 | 963 | static void __mq_set_clear_dirty(struct mq_policy *mq, dm_oblock_t oblock, bool set) |
01911c19 | 964 | { |
01911c19 JT |
965 | struct entry *e; |
966 | ||
01911c19 | 967 | e = hash_lookup(mq, oblock); |
633618e3 | 968 | BUG_ON(!e || !in_cache(mq, e)); |
01911c19 | 969 | |
633618e3 JT |
970 | del(mq, e); |
971 | e->dirty = set; | |
972 | push(mq, e); | |
01911c19 JT |
973 | } |
974 | ||
975 | static void mq_set_dirty(struct dm_cache_policy *p, dm_oblock_t oblock) | |
976 | { | |
633618e3 JT |
977 | struct mq_policy *mq = to_mq_policy(p); |
978 | ||
979 | mutex_lock(&mq->lock); | |
980 | __mq_set_clear_dirty(mq, oblock, true); | |
981 | mutex_unlock(&mq->lock); | |
01911c19 JT |
982 | } |
983 | ||
984 | static void mq_clear_dirty(struct dm_cache_policy *p, dm_oblock_t oblock) | |
985 | { | |
633618e3 JT |
986 | struct mq_policy *mq = to_mq_policy(p); |
987 | ||
988 | mutex_lock(&mq->lock); | |
989 | __mq_set_clear_dirty(mq, oblock, false); | |
990 | mutex_unlock(&mq->lock); | |
01911c19 JT |
991 | } |
992 | ||
f2836352 JT |
993 | static int mq_load_mapping(struct dm_cache_policy *p, |
994 | dm_oblock_t oblock, dm_cblock_t cblock, | |
995 | uint32_t hint, bool hint_valid) | |
996 | { | |
997 | struct mq_policy *mq = to_mq_policy(p); | |
998 | struct entry *e; | |
999 | ||
633618e3 | 1000 | e = alloc_particular_entry(&mq->cache_pool, cblock); |
f2836352 | 1001 | e->oblock = oblock; |
01911c19 | 1002 | e->dirty = false; /* this gets corrected in a minute */ |
f2836352 JT |
1003 | e->hit_count = hint_valid ? hint : 1; |
1004 | e->generation = mq->generation; | |
1005 | push(mq, e); | |
1006 | ||
1007 | return 0; | |
1008 | } | |
1009 | ||
633618e3 JT |
1010 | static int mq_save_hints(struct mq_policy *mq, struct queue *q, |
1011 | policy_walk_fn fn, void *context) | |
1012 | { | |
1013 | int r; | |
1014 | unsigned level; | |
1015 | struct entry *e; | |
1016 | ||
1017 | for (level = 0; level < NR_QUEUE_LEVELS; level++) | |
1018 | list_for_each_entry(e, q->qs + level, list) { | |
1019 | r = fn(context, infer_cblock(&mq->cache_pool, e), | |
1020 | e->oblock, e->hit_count); | |
1021 | if (r) | |
1022 | return r; | |
1023 | } | |
1024 | ||
1025 | return 0; | |
1026 | } | |
1027 | ||
f2836352 JT |
1028 | static int mq_walk_mappings(struct dm_cache_policy *p, policy_walk_fn fn, |
1029 | void *context) | |
1030 | { | |
1031 | struct mq_policy *mq = to_mq_policy(p); | |
1032 | int r = 0; | |
f2836352 JT |
1033 | |
1034 | mutex_lock(&mq->lock); | |
1035 | ||
633618e3 JT |
1036 | r = mq_save_hints(mq, &mq->cache_clean, fn, context); |
1037 | if (!r) | |
1038 | r = mq_save_hints(mq, &mq->cache_dirty, fn, context); | |
f2836352 | 1039 | |
f2836352 JT |
1040 | mutex_unlock(&mq->lock); |
1041 | ||
1042 | return r; | |
1043 | } | |
1044 | ||
633618e3 | 1045 | static void __remove_mapping(struct mq_policy *mq, dm_oblock_t oblock) |
f2836352 | 1046 | { |
b936bf8b GU |
1047 | struct entry *e; |
1048 | ||
b936bf8b | 1049 | e = hash_lookup(mq, oblock); |
633618e3 | 1050 | BUG_ON(!e || !in_cache(mq, e)); |
f2836352 JT |
1051 | |
1052 | del(mq, e); | |
633618e3 JT |
1053 | free_entry(&mq->cache_pool, e); |
1054 | } | |
1055 | ||
1056 | static void mq_remove_mapping(struct dm_cache_policy *p, dm_oblock_t oblock) | |
1057 | { | |
1058 | struct mq_policy *mq = to_mq_policy(p); | |
f2836352 | 1059 | |
633618e3 JT |
1060 | mutex_lock(&mq->lock); |
1061 | __remove_mapping(mq, oblock); | |
f2836352 JT |
1062 | mutex_unlock(&mq->lock); |
1063 | } | |
1064 | ||
532906aa JT |
1065 | static int __remove_cblock(struct mq_policy *mq, dm_cblock_t cblock) |
1066 | { | |
1067 | struct entry *e = epool_find(&mq->cache_pool, cblock); | |
1068 | ||
1069 | if (!e) | |
1070 | return -ENODATA; | |
1071 | ||
1072 | del(mq, e); | |
1073 | free_entry(&mq->cache_pool, e); | |
1074 | ||
1075 | return 0; | |
1076 | } | |
1077 | ||
1078 | static int mq_remove_cblock(struct dm_cache_policy *p, dm_cblock_t cblock) | |
1079 | { | |
1080 | int r; | |
1081 | struct mq_policy *mq = to_mq_policy(p); | |
1082 | ||
1083 | mutex_lock(&mq->lock); | |
1084 | r = __remove_cblock(mq, cblock); | |
1085 | mutex_unlock(&mq->lock); | |
1086 | ||
1087 | return r; | |
1088 | } | |
1089 | ||
01911c19 JT |
1090 | static int __mq_writeback_work(struct mq_policy *mq, dm_oblock_t *oblock, |
1091 | dm_cblock_t *cblock) | |
1092 | { | |
1093 | struct entry *e = pop(mq, &mq->cache_dirty); | |
1094 | ||
1095 | if (!e) | |
1096 | return -ENODATA; | |
1097 | ||
1098 | *oblock = e->oblock; | |
633618e3 | 1099 | *cblock = infer_cblock(&mq->cache_pool, e); |
01911c19 JT |
1100 | e->dirty = false; |
1101 | push(mq, e); | |
1102 | ||
1103 | return 0; | |
1104 | } | |
1105 | ||
1106 | static int mq_writeback_work(struct dm_cache_policy *p, dm_oblock_t *oblock, | |
1107 | dm_cblock_t *cblock) | |
1108 | { | |
1109 | int r; | |
1110 | struct mq_policy *mq = to_mq_policy(p); | |
1111 | ||
1112 | mutex_lock(&mq->lock); | |
1113 | r = __mq_writeback_work(mq, oblock, cblock); | |
1114 | mutex_unlock(&mq->lock); | |
1115 | ||
1116 | return r; | |
1117 | } | |
1118 | ||
633618e3 JT |
1119 | static void __force_mapping(struct mq_policy *mq, |
1120 | dm_oblock_t current_oblock, dm_oblock_t new_oblock) | |
f2836352 JT |
1121 | { |
1122 | struct entry *e = hash_lookup(mq, current_oblock); | |
1123 | ||
633618e3 JT |
1124 | if (e && in_cache(mq, e)) { |
1125 | del(mq, e); | |
1126 | e->oblock = new_oblock; | |
1127 | e->dirty = true; | |
1128 | push(mq, e); | |
1129 | } | |
f2836352 JT |
1130 | } |
1131 | ||
1132 | static void mq_force_mapping(struct dm_cache_policy *p, | |
1133 | dm_oblock_t current_oblock, dm_oblock_t new_oblock) | |
1134 | { | |
1135 | struct mq_policy *mq = to_mq_policy(p); | |
1136 | ||
1137 | mutex_lock(&mq->lock); | |
633618e3 | 1138 | __force_mapping(mq, current_oblock, new_oblock); |
f2836352 JT |
1139 | mutex_unlock(&mq->lock); |
1140 | } | |
1141 | ||
1142 | static dm_cblock_t mq_residency(struct dm_cache_policy *p) | |
1143 | { | |
99ba2ae4 | 1144 | dm_cblock_t r; |
f2836352 JT |
1145 | struct mq_policy *mq = to_mq_policy(p); |
1146 | ||
99ba2ae4 | 1147 | mutex_lock(&mq->lock); |
633618e3 | 1148 | r = to_cblock(mq->cache_pool.nr_allocated); |
99ba2ae4 JT |
1149 | mutex_unlock(&mq->lock); |
1150 | ||
1151 | return r; | |
f2836352 JT |
1152 | } |
1153 | ||
1154 | static void mq_tick(struct dm_cache_policy *p) | |
1155 | { | |
1156 | struct mq_policy *mq = to_mq_policy(p); | |
1157 | unsigned long flags; | |
1158 | ||
1159 | spin_lock_irqsave(&mq->tick_lock, flags); | |
1160 | mq->tick_protected++; | |
1161 | spin_unlock_irqrestore(&mq->tick_lock, flags); | |
1162 | } | |
1163 | ||
1164 | static int mq_set_config_value(struct dm_cache_policy *p, | |
1165 | const char *key, const char *value) | |
1166 | { | |
1167 | struct mq_policy *mq = to_mq_policy(p); | |
f2836352 JT |
1168 | unsigned long tmp; |
1169 | ||
f2836352 JT |
1170 | if (kstrtoul(value, 10, &tmp)) |
1171 | return -EINVAL; | |
1172 | ||
78e03d69 JT |
1173 | if (!strcasecmp(key, "random_threshold")) { |
1174 | mq->tracker.thresholds[PATTERN_RANDOM] = tmp; | |
1175 | ||
1176 | } else if (!strcasecmp(key, "sequential_threshold")) { | |
1177 | mq->tracker.thresholds[PATTERN_SEQUENTIAL] = tmp; | |
1178 | ||
1179 | } else if (!strcasecmp(key, "discard_promote_adjustment")) | |
1180 | mq->discard_promote_adjustment = tmp; | |
1181 | ||
1182 | else if (!strcasecmp(key, "read_promote_adjustment")) | |
1183 | mq->read_promote_adjustment = tmp; | |
1184 | ||
1185 | else if (!strcasecmp(key, "write_promote_adjustment")) | |
1186 | mq->write_promote_adjustment = tmp; | |
1187 | ||
1188 | else | |
1189 | return -EINVAL; | |
f2836352 JT |
1190 | |
1191 | return 0; | |
1192 | } | |
1193 | ||
1194 | static int mq_emit_config_values(struct dm_cache_policy *p, char *result, unsigned maxlen) | |
1195 | { | |
1196 | ssize_t sz = 0; | |
1197 | struct mq_policy *mq = to_mq_policy(p); | |
1198 | ||
78e03d69 JT |
1199 | DMEMIT("10 random_threshold %u " |
1200 | "sequential_threshold %u " | |
1201 | "discard_promote_adjustment %u " | |
1202 | "read_promote_adjustment %u " | |
1203 | "write_promote_adjustment %u", | |
f2836352 | 1204 | mq->tracker.thresholds[PATTERN_RANDOM], |
78e03d69 JT |
1205 | mq->tracker.thresholds[PATTERN_SEQUENTIAL], |
1206 | mq->discard_promote_adjustment, | |
1207 | mq->read_promote_adjustment, | |
1208 | mq->write_promote_adjustment); | |
f2836352 JT |
1209 | |
1210 | return 0; | |
1211 | } | |
1212 | ||
1213 | /* Init the policy plugin interface function pointers. */ | |
1214 | static void init_policy_functions(struct mq_policy *mq) | |
1215 | { | |
1216 | mq->policy.destroy = mq_destroy; | |
1217 | mq->policy.map = mq_map; | |
1218 | mq->policy.lookup = mq_lookup; | |
01911c19 JT |
1219 | mq->policy.set_dirty = mq_set_dirty; |
1220 | mq->policy.clear_dirty = mq_clear_dirty; | |
f2836352 JT |
1221 | mq->policy.load_mapping = mq_load_mapping; |
1222 | mq->policy.walk_mappings = mq_walk_mappings; | |
1223 | mq->policy.remove_mapping = mq_remove_mapping; | |
532906aa | 1224 | mq->policy.remove_cblock = mq_remove_cblock; |
01911c19 | 1225 | mq->policy.writeback_work = mq_writeback_work; |
f2836352 JT |
1226 | mq->policy.force_mapping = mq_force_mapping; |
1227 | mq->policy.residency = mq_residency; | |
1228 | mq->policy.tick = mq_tick; | |
1229 | mq->policy.emit_config_values = mq_emit_config_values; | |
1230 | mq->policy.set_config_value = mq_set_config_value; | |
1231 | } | |
1232 | ||
1233 | static struct dm_cache_policy *mq_create(dm_cblock_t cache_size, | |
1234 | sector_t origin_size, | |
1235 | sector_t cache_block_size) | |
1236 | { | |
f2836352 JT |
1237 | struct mq_policy *mq = kzalloc(sizeof(*mq), GFP_KERNEL); |
1238 | ||
1239 | if (!mq) | |
1240 | return NULL; | |
1241 | ||
1242 | init_policy_functions(mq); | |
1243 | iot_init(&mq->tracker, SEQUENTIAL_THRESHOLD_DEFAULT, RANDOM_THRESHOLD_DEFAULT); | |
f2836352 | 1244 | mq->cache_size = cache_size; |
633618e3 JT |
1245 | |
1246 | if (epool_init(&mq->pre_cache_pool, from_cblock(cache_size))) { | |
1247 | DMERR("couldn't initialize pool of pre-cache entries"); | |
1248 | goto bad_pre_cache_init; | |
1249 | } | |
1250 | ||
1251 | if (epool_init(&mq->cache_pool, from_cblock(cache_size))) { | |
1252 | DMERR("couldn't initialize pool of cache entries"); | |
1253 | goto bad_cache_init; | |
1254 | } | |
1255 | ||
f2836352 JT |
1256 | mq->tick_protected = 0; |
1257 | mq->tick = 0; | |
1258 | mq->hit_count = 0; | |
1259 | mq->generation = 0; | |
78e03d69 JT |
1260 | mq->discard_promote_adjustment = DEFAULT_DISCARD_PROMOTE_ADJUSTMENT; |
1261 | mq->read_promote_adjustment = DEFAULT_READ_PROMOTE_ADJUSTMENT; | |
1262 | mq->write_promote_adjustment = DEFAULT_WRITE_PROMOTE_ADJUSTMENT; | |
f2836352 JT |
1263 | mutex_init(&mq->lock); |
1264 | spin_lock_init(&mq->tick_lock); | |
f2836352 JT |
1265 | |
1266 | queue_init(&mq->pre_cache); | |
01911c19 JT |
1267 | queue_init(&mq->cache_clean); |
1268 | queue_init(&mq->cache_dirty); | |
1269 | ||
f2836352 JT |
1270 | mq->generation_period = max((unsigned) from_cblock(cache_size), 1024U); |
1271 | ||
f2836352 JT |
1272 | mq->nr_buckets = next_power(from_cblock(cache_size) / 2, 16); |
1273 | mq->hash_bits = ffs(mq->nr_buckets) - 1; | |
14f398ca | 1274 | mq->table = vzalloc(sizeof(*mq->table) * mq->nr_buckets); |
f2836352 JT |
1275 | if (!mq->table) |
1276 | goto bad_alloc_table; | |
1277 | ||
f2836352 JT |
1278 | return &mq->policy; |
1279 | ||
f2836352 | 1280 | bad_alloc_table: |
633618e3 JT |
1281 | epool_exit(&mq->cache_pool); |
1282 | bad_cache_init: | |
1283 | epool_exit(&mq->pre_cache_pool); | |
1284 | bad_pre_cache_init: | |
f2836352 JT |
1285 | kfree(mq); |
1286 | ||
1287 | return NULL; | |
1288 | } | |
1289 | ||
1290 | /*----------------------------------------------------------------*/ | |
1291 | ||
1292 | static struct dm_cache_policy_type mq_policy_type = { | |
1293 | .name = "mq", | |
f1afb36a | 1294 | .version = {1, 3, 0}, |
f2836352 JT |
1295 | .hint_size = 4, |
1296 | .owner = THIS_MODULE, | |
1297 | .create = mq_create | |
1298 | }; | |
1299 | ||
1300 | static struct dm_cache_policy_type default_policy_type = { | |
1301 | .name = "default", | |
f1afb36a | 1302 | .version = {1, 3, 0}, |
f2836352 JT |
1303 | .hint_size = 4, |
1304 | .owner = THIS_MODULE, | |
2e68c4e6 MS |
1305 | .create = mq_create, |
1306 | .real = &mq_policy_type | |
f2836352 JT |
1307 | }; |
1308 | ||
1309 | static int __init mq_init(void) | |
1310 | { | |
1311 | int r; | |
1312 | ||
1313 | mq_entry_cache = kmem_cache_create("dm_mq_policy_cache_entry", | |
1314 | sizeof(struct entry), | |
1315 | __alignof__(struct entry), | |
1316 | 0, NULL); | |
1317 | if (!mq_entry_cache) | |
1318 | goto bad; | |
1319 | ||
1320 | r = dm_cache_policy_register(&mq_policy_type); | |
1321 | if (r) { | |
1322 | DMERR("register failed %d", r); | |
1323 | goto bad_register_mq; | |
1324 | } | |
1325 | ||
1326 | r = dm_cache_policy_register(&default_policy_type); | |
1327 | if (!r) { | |
4e7f506f MS |
1328 | DMINFO("version %u.%u.%u loaded", |
1329 | mq_policy_type.version[0], | |
1330 | mq_policy_type.version[1], | |
1331 | mq_policy_type.version[2]); | |
f2836352 JT |
1332 | return 0; |
1333 | } | |
1334 | ||
1335 | DMERR("register failed (as default) %d", r); | |
1336 | ||
1337 | dm_cache_policy_unregister(&mq_policy_type); | |
1338 | bad_register_mq: | |
1339 | kmem_cache_destroy(mq_entry_cache); | |
1340 | bad: | |
1341 | return -ENOMEM; | |
1342 | } | |
1343 | ||
1344 | static void __exit mq_exit(void) | |
1345 | { | |
1346 | dm_cache_policy_unregister(&mq_policy_type); | |
1347 | dm_cache_policy_unregister(&default_policy_type); | |
1348 | ||
1349 | kmem_cache_destroy(mq_entry_cache); | |
1350 | } | |
1351 | ||
1352 | module_init(mq_init); | |
1353 | module_exit(mq_exit); | |
1354 | ||
1355 | MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); | |
1356 | MODULE_LICENSE("GPL"); | |
1357 | MODULE_DESCRIPTION("mq cache policy"); | |
1358 | ||
1359 | MODULE_ALIAS("dm-cache-default"); |