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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 | */ | |
184 | static struct list_head *queue_pop(struct queue *q) | |
185 | { | |
186 | unsigned level; | |
187 | struct list_head *r; | |
188 | ||
189 | for (level = 0; level < NR_QUEUE_LEVELS; level++) | |
190 | if (!list_empty(q->qs + level)) { | |
191 | r = q->qs[level].next; | |
192 | list_del(r); | |
193 | ||
194 | /* have we just emptied the bottom level? */ | |
195 | if (level == 0 && list_empty(q->qs)) | |
196 | queue_shift_down(q); | |
197 | ||
198 | return r; | |
199 | } | |
200 | ||
201 | return NULL; | |
202 | } | |
203 | ||
204 | static struct list_head *list_pop(struct list_head *lh) | |
205 | { | |
206 | struct list_head *r = lh->next; | |
207 | ||
208 | BUG_ON(!r); | |
209 | list_del_init(r); | |
210 | ||
211 | return r; | |
212 | } | |
213 | ||
214 | /*----------------------------------------------------------------*/ | |
215 | ||
216 | /* | |
217 | * Describes a cache entry. Used in both the cache and the pre_cache. | |
218 | */ | |
219 | struct entry { | |
220 | struct hlist_node hlist; | |
221 | struct list_head list; | |
222 | dm_oblock_t oblock; | |
f2836352 JT |
223 | |
224 | /* | |
225 | * FIXME: pack these better | |
226 | */ | |
01911c19 | 227 | bool dirty:1; |
f2836352 JT |
228 | unsigned hit_count; |
229 | unsigned generation; | |
230 | unsigned tick; | |
231 | }; | |
232 | ||
633618e3 JT |
233 | /* |
234 | * Rather than storing the cblock in an entry, we allocate all entries in | |
235 | * an array, and infer the cblock from the entry position. | |
236 | * | |
237 | * Free entries are linked together into a list. | |
238 | */ | |
239 | struct entry_pool { | |
240 | struct entry *entries, *entries_end; | |
241 | struct list_head free; | |
242 | unsigned nr_allocated; | |
243 | }; | |
244 | ||
245 | static int epool_init(struct entry_pool *ep, unsigned nr_entries) | |
246 | { | |
247 | unsigned i; | |
248 | ||
249 | ep->entries = vzalloc(sizeof(struct entry) * nr_entries); | |
250 | if (!ep->entries) | |
251 | return -ENOMEM; | |
252 | ||
253 | ep->entries_end = ep->entries + nr_entries; | |
254 | ||
255 | INIT_LIST_HEAD(&ep->free); | |
256 | for (i = 0; i < nr_entries; i++) | |
257 | list_add(&ep->entries[i].list, &ep->free); | |
258 | ||
259 | ep->nr_allocated = 0; | |
260 | ||
261 | return 0; | |
262 | } | |
263 | ||
264 | static void epool_exit(struct entry_pool *ep) | |
265 | { | |
266 | vfree(ep->entries); | |
267 | } | |
268 | ||
269 | static struct entry *alloc_entry(struct entry_pool *ep) | |
270 | { | |
271 | struct entry *e; | |
272 | ||
273 | if (list_empty(&ep->free)) | |
274 | return NULL; | |
275 | ||
276 | e = list_entry(list_pop(&ep->free), struct entry, list); | |
277 | INIT_LIST_HEAD(&e->list); | |
278 | INIT_HLIST_NODE(&e->hlist); | |
279 | ep->nr_allocated++; | |
280 | ||
281 | return e; | |
282 | } | |
283 | ||
284 | /* | |
285 | * This assumes the cblock hasn't already been allocated. | |
286 | */ | |
287 | static struct entry *alloc_particular_entry(struct entry_pool *ep, dm_cblock_t cblock) | |
288 | { | |
289 | struct entry *e = ep->entries + from_cblock(cblock); | |
633618e3 | 290 | |
b8158051 | 291 | list_del_init(&e->list); |
633618e3 JT |
292 | INIT_HLIST_NODE(&e->hlist); |
293 | ep->nr_allocated++; | |
294 | ||
295 | return e; | |
296 | } | |
297 | ||
298 | static void free_entry(struct entry_pool *ep, struct entry *e) | |
299 | { | |
300 | BUG_ON(!ep->nr_allocated); | |
301 | ep->nr_allocated--; | |
302 | INIT_HLIST_NODE(&e->hlist); | |
303 | list_add(&e->list, &ep->free); | |
304 | } | |
305 | ||
532906aa JT |
306 | /* |
307 | * Returns NULL if the entry is free. | |
308 | */ | |
309 | static struct entry *epool_find(struct entry_pool *ep, dm_cblock_t cblock) | |
310 | { | |
311 | struct entry *e = ep->entries + from_cblock(cblock); | |
7b6b2bc9 | 312 | return !hlist_unhashed(&e->hlist) ? e : NULL; |
532906aa JT |
313 | } |
314 | ||
633618e3 JT |
315 | static bool epool_empty(struct entry_pool *ep) |
316 | { | |
317 | return list_empty(&ep->free); | |
318 | } | |
319 | ||
320 | static bool in_pool(struct entry_pool *ep, struct entry *e) | |
321 | { | |
322 | return e >= ep->entries && e < ep->entries_end; | |
323 | } | |
324 | ||
325 | static dm_cblock_t infer_cblock(struct entry_pool *ep, struct entry *e) | |
326 | { | |
327 | return to_cblock(e - ep->entries); | |
328 | } | |
329 | ||
330 | /*----------------------------------------------------------------*/ | |
331 | ||
f2836352 JT |
332 | struct mq_policy { |
333 | struct dm_cache_policy policy; | |
334 | ||
335 | /* protects everything */ | |
336 | struct mutex lock; | |
337 | dm_cblock_t cache_size; | |
338 | struct io_tracker tracker; | |
339 | ||
633618e3 JT |
340 | /* |
341 | * Entries come from two pools, one of pre-cache entries, and one | |
342 | * for the cache proper. | |
343 | */ | |
344 | struct entry_pool pre_cache_pool; | |
345 | struct entry_pool cache_pool; | |
346 | ||
f2836352 | 347 | /* |
01911c19 JT |
348 | * We maintain three queues of entries. The cache proper, |
349 | * consisting of a clean and dirty queue, contains the currently | |
350 | * active mappings. Whereas the pre_cache tracks blocks that | |
351 | * are being hit frequently and potential candidates for promotion | |
352 | * to the cache. | |
f2836352 JT |
353 | */ |
354 | struct queue pre_cache; | |
01911c19 JT |
355 | struct queue cache_clean; |
356 | struct queue cache_dirty; | |
f2836352 JT |
357 | |
358 | /* | |
359 | * Keeps track of time, incremented by the core. We use this to | |
360 | * avoid attributing multiple hits within the same tick. | |
361 | * | |
362 | * Access to tick_protected should be done with the spin lock held. | |
363 | * It's copied to tick at the start of the map function (within the | |
364 | * mutex). | |
365 | */ | |
366 | spinlock_t tick_lock; | |
367 | unsigned tick_protected; | |
368 | unsigned tick; | |
369 | ||
370 | /* | |
371 | * A count of the number of times the map function has been called | |
372 | * and found an entry in the pre_cache or cache. Currently used to | |
373 | * calculate the generation. | |
374 | */ | |
375 | unsigned hit_count; | |
376 | ||
377 | /* | |
378 | * A generation is a longish period that is used to trigger some | |
379 | * book keeping effects. eg, decrementing hit counts on entries. | |
380 | * This is needed to allow the cache to evolve as io patterns | |
381 | * change. | |
382 | */ | |
383 | unsigned generation; | |
384 | unsigned generation_period; /* in lookups (will probably change) */ | |
385 | ||
386 | /* | |
387 | * Entries in the pre_cache whose hit count passes the promotion | |
388 | * threshold move to the cache proper. Working out the correct | |
389 | * value for the promotion_threshold is crucial to this policy. | |
390 | */ | |
391 | unsigned promote_threshold; | |
392 | ||
78e03d69 JT |
393 | unsigned discard_promote_adjustment; |
394 | unsigned read_promote_adjustment; | |
395 | unsigned write_promote_adjustment; | |
396 | ||
f2836352 JT |
397 | /* |
398 | * The hash table allows us to quickly find an entry by origin | |
399 | * block. Both pre_cache and cache entries are in here. | |
400 | */ | |
401 | unsigned nr_buckets; | |
402 | dm_block_t hash_bits; | |
403 | struct hlist_head *table; | |
404 | }; | |
405 | ||
78e03d69 JT |
406 | #define DEFAULT_DISCARD_PROMOTE_ADJUSTMENT 1 |
407 | #define DEFAULT_READ_PROMOTE_ADJUSTMENT 4 | |
408 | #define DEFAULT_WRITE_PROMOTE_ADJUSTMENT 8 | |
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 | ||
521 | /* | |
522 | * Has this entry already been updated? | |
523 | */ | |
524 | static bool updated_this_tick(struct mq_policy *mq, struct entry *e) | |
525 | { | |
526 | return mq->tick == e->tick; | |
527 | } | |
528 | ||
529 | /* | |
530 | * The promotion threshold is adjusted every generation. As are the counts | |
531 | * of the entries. | |
532 | * | |
533 | * At the moment the threshold is taken by averaging the hit counts of some | |
01911c19 JT |
534 | * of the entries in the cache (the first 20 entries across all levels in |
535 | * ascending order, giving preference to the clean entries at each level). | |
f2836352 JT |
536 | * |
537 | * We can be much cleverer than this though. For example, each promotion | |
538 | * could bump up the threshold helping to prevent churn. Much more to do | |
539 | * here. | |
540 | */ | |
541 | ||
542 | #define MAX_TO_AVERAGE 20 | |
543 | ||
544 | static void check_generation(struct mq_policy *mq) | |
545 | { | |
546 | unsigned total = 0, nr = 0, count = 0, level; | |
547 | struct list_head *head; | |
548 | struct entry *e; | |
549 | ||
633618e3 | 550 | if ((mq->hit_count >= mq->generation_period) && (epool_empty(&mq->cache_pool))) { |
f2836352 JT |
551 | mq->hit_count = 0; |
552 | mq->generation++; | |
553 | ||
554 | for (level = 0; level < NR_QUEUE_LEVELS && count < MAX_TO_AVERAGE; level++) { | |
01911c19 JT |
555 | head = mq->cache_clean.qs + level; |
556 | list_for_each_entry(e, head, list) { | |
557 | nr++; | |
558 | total += e->hit_count; | |
559 | ||
560 | if (++count >= MAX_TO_AVERAGE) | |
561 | break; | |
562 | } | |
563 | ||
564 | head = mq->cache_dirty.qs + level; | |
f2836352 JT |
565 | list_for_each_entry(e, head, list) { |
566 | nr++; | |
567 | total += e->hit_count; | |
568 | ||
569 | if (++count >= MAX_TO_AVERAGE) | |
570 | break; | |
571 | } | |
572 | } | |
573 | ||
574 | mq->promote_threshold = nr ? total / nr : 1; | |
575 | if (mq->promote_threshold * nr < total) | |
576 | mq->promote_threshold++; | |
577 | } | |
578 | } | |
579 | ||
580 | /* | |
581 | * Whenever we use an entry we bump up it's hit counter, and push it to the | |
582 | * back to it's current level. | |
583 | */ | |
584 | static void requeue_and_update_tick(struct mq_policy *mq, struct entry *e) | |
585 | { | |
586 | if (updated_this_tick(mq, e)) | |
587 | return; | |
588 | ||
589 | e->hit_count++; | |
590 | mq->hit_count++; | |
591 | check_generation(mq); | |
592 | ||
593 | /* generation adjustment, to stop the counts increasing forever. */ | |
594 | /* FIXME: divide? */ | |
595 | /* e->hit_count -= min(e->hit_count - 1, mq->generation - e->generation); */ | |
596 | e->generation = mq->generation; | |
597 | ||
598 | del(mq, e); | |
599 | push(mq, e); | |
600 | } | |
601 | ||
602 | /* | |
603 | * Demote the least recently used entry from the cache to the pre_cache. | |
604 | * Returns the new cache entry to use, and the old origin block it was | |
605 | * mapped to. | |
606 | * | |
607 | * We drop the hit count on the demoted entry back to 1 to stop it bouncing | |
608 | * straight back into the cache if it's subsequently hit. There are | |
609 | * various options here, and more experimentation would be good: | |
610 | * | |
611 | * - just forget about the demoted entry completely (ie. don't insert it | |
612 | into the pre_cache). | |
613 | * - divide the hit count rather that setting to some hard coded value. | |
614 | * - set the hit count to a hard coded value other than 1, eg, is it better | |
615 | * if it goes in at level 2? | |
616 | */ | |
633618e3 | 617 | static int demote_cblock(struct mq_policy *mq, dm_oblock_t *oblock) |
f2836352 | 618 | { |
01911c19 | 619 | struct entry *demoted = pop(mq, &mq->cache_clean); |
f2836352 | 620 | |
01911c19 JT |
621 | if (!demoted) |
622 | /* | |
623 | * We could get a block from mq->cache_dirty, but that | |
624 | * would add extra latency to the triggering bio as it | |
625 | * waits for the writeback. Better to not promote this | |
626 | * time and hope there's a clean block next time this block | |
627 | * is hit. | |
628 | */ | |
629 | return -ENOSPC; | |
630 | ||
f2836352 | 631 | *oblock = demoted->oblock; |
633618e3 JT |
632 | free_entry(&mq->cache_pool, demoted); |
633 | ||
634 | /* | |
635 | * We used to put the demoted block into the pre-cache, but I think | |
636 | * it's simpler to just let it work it's way up from zero again. | |
637 | * Stops blocks flickering in and out of the cache. | |
638 | */ | |
f2836352 | 639 | |
01911c19 | 640 | return 0; |
f2836352 JT |
641 | } |
642 | ||
643 | /* | |
644 | * We modify the basic promotion_threshold depending on the specific io. | |
645 | * | |
646 | * If the origin block has been discarded then there's no cost to copy it | |
647 | * to the cache. | |
648 | * | |
649 | * We bias towards reads, since they can be demoted at no cost if they | |
650 | * haven't been dirtied. | |
651 | */ | |
f2836352 JT |
652 | static unsigned adjusted_promote_threshold(struct mq_policy *mq, |
653 | bool discarded_oblock, int data_dir) | |
654 | { | |
c86c3070 | 655 | if (data_dir == READ) |
78e03d69 | 656 | return mq->promote_threshold + mq->read_promote_adjustment; |
c86c3070 JT |
657 | |
658 | if (discarded_oblock && (any_free_cblocks(mq) || any_clean_cblocks(mq))) { | |
f2836352 JT |
659 | /* |
660 | * We don't need to do any copying at all, so give this a | |
c86c3070 | 661 | * very low threshold. |
f2836352 | 662 | */ |
78e03d69 | 663 | return mq->discard_promote_adjustment; |
c86c3070 | 664 | } |
f2836352 | 665 | |
78e03d69 | 666 | return mq->promote_threshold + mq->write_promote_adjustment; |
f2836352 JT |
667 | } |
668 | ||
669 | static bool should_promote(struct mq_policy *mq, struct entry *e, | |
670 | bool discarded_oblock, int data_dir) | |
671 | { | |
672 | return e->hit_count >= | |
673 | adjusted_promote_threshold(mq, discarded_oblock, data_dir); | |
674 | } | |
675 | ||
676 | static int cache_entry_found(struct mq_policy *mq, | |
677 | struct entry *e, | |
678 | struct policy_result *result) | |
679 | { | |
680 | requeue_and_update_tick(mq, e); | |
681 | ||
633618e3 | 682 | if (in_cache(mq, e)) { |
f2836352 | 683 | result->op = POLICY_HIT; |
633618e3 | 684 | result->cblock = infer_cblock(&mq->cache_pool, e); |
f2836352 JT |
685 | } |
686 | ||
687 | return 0; | |
688 | } | |
689 | ||
690 | /* | |
0184b44e | 691 | * Moves an entry from the pre_cache to the cache. The main work is |
f2836352 JT |
692 | * finding which cache block to use. |
693 | */ | |
694 | static int pre_cache_to_cache(struct mq_policy *mq, struct entry *e, | |
695 | struct policy_result *result) | |
696 | { | |
01911c19 | 697 | int r; |
633618e3 | 698 | struct entry *new_e; |
f2836352 | 699 | |
633618e3 JT |
700 | /* Ensure there's a free cblock in the cache */ |
701 | if (epool_empty(&mq->cache_pool)) { | |
f2836352 | 702 | result->op = POLICY_REPLACE; |
633618e3 | 703 | r = demote_cblock(mq, &result->old_oblock); |
01911c19 JT |
704 | if (r) { |
705 | result->op = POLICY_MISS; | |
706 | return 0; | |
707 | } | |
f2836352 JT |
708 | } else |
709 | result->op = POLICY_NEW; | |
710 | ||
633618e3 JT |
711 | new_e = alloc_entry(&mq->cache_pool); |
712 | BUG_ON(!new_e); | |
713 | ||
714 | new_e->oblock = e->oblock; | |
715 | new_e->dirty = false; | |
716 | new_e->hit_count = e->hit_count; | |
717 | new_e->generation = e->generation; | |
718 | new_e->tick = e->tick; | |
f2836352 JT |
719 | |
720 | del(mq, e); | |
633618e3 JT |
721 | free_entry(&mq->pre_cache_pool, e); |
722 | push(mq, new_e); | |
723 | ||
724 | result->cblock = infer_cblock(&mq->cache_pool, new_e); | |
f2836352 JT |
725 | |
726 | return 0; | |
727 | } | |
728 | ||
729 | static int pre_cache_entry_found(struct mq_policy *mq, struct entry *e, | |
730 | bool can_migrate, bool discarded_oblock, | |
731 | int data_dir, struct policy_result *result) | |
732 | { | |
733 | int r = 0; | |
734 | bool updated = updated_this_tick(mq, e); | |
735 | ||
f2836352 | 736 | if ((!discarded_oblock && updated) || |
af95e7a6 JT |
737 | !should_promote(mq, e, discarded_oblock, data_dir)) { |
738 | requeue_and_update_tick(mq, e); | |
f2836352 | 739 | result->op = POLICY_MISS; |
af95e7a6 JT |
740 | |
741 | } else if (!can_migrate) | |
f2836352 | 742 | r = -EWOULDBLOCK; |
af95e7a6 JT |
743 | |
744 | else { | |
745 | requeue_and_update_tick(mq, e); | |
f2836352 | 746 | r = pre_cache_to_cache(mq, e, result); |
af95e7a6 | 747 | } |
f2836352 JT |
748 | |
749 | return r; | |
750 | } | |
751 | ||
752 | static void insert_in_pre_cache(struct mq_policy *mq, | |
753 | dm_oblock_t oblock) | |
754 | { | |
633618e3 | 755 | struct entry *e = alloc_entry(&mq->pre_cache_pool); |
f2836352 JT |
756 | |
757 | if (!e) | |
758 | /* | |
759 | * There's no spare entry structure, so we grab the least | |
760 | * used one from the pre_cache. | |
761 | */ | |
762 | e = pop(mq, &mq->pre_cache); | |
763 | ||
764 | if (unlikely(!e)) { | |
765 | DMWARN("couldn't pop from pre cache"); | |
766 | return; | |
767 | } | |
768 | ||
633618e3 JT |
769 | e->dirty = false; |
770 | e->oblock = oblock; | |
771 | e->hit_count = 1; | |
772 | e->generation = mq->generation; | |
773 | push(mq, e); | |
f2836352 JT |
774 | } |
775 | ||
776 | static void insert_in_cache(struct mq_policy *mq, dm_oblock_t oblock, | |
777 | struct policy_result *result) | |
778 | { | |
c86c3070 | 779 | int r; |
f2836352 | 780 | struct entry *e; |
f2836352 | 781 | |
633618e3 JT |
782 | if (epool_empty(&mq->cache_pool)) { |
783 | result->op = POLICY_REPLACE; | |
784 | r = demote_cblock(mq, &result->old_oblock); | |
c86c3070 JT |
785 | if (unlikely(r)) { |
786 | result->op = POLICY_MISS; | |
787 | insert_in_pre_cache(mq, oblock); | |
788 | return; | |
789 | } | |
f2836352 | 790 | |
c86c3070 JT |
791 | /* |
792 | * This will always succeed, since we've just demoted. | |
793 | */ | |
633618e3 JT |
794 | e = alloc_entry(&mq->cache_pool); |
795 | BUG_ON(!e); | |
c86c3070 JT |
796 | |
797 | } else { | |
633618e3 | 798 | e = alloc_entry(&mq->cache_pool); |
c86c3070 | 799 | result->op = POLICY_NEW; |
f2836352 JT |
800 | } |
801 | ||
802 | e->oblock = oblock; | |
01911c19 | 803 | e->dirty = false; |
f2836352 JT |
804 | e->hit_count = 1; |
805 | e->generation = mq->generation; | |
806 | push(mq, e); | |
807 | ||
633618e3 | 808 | result->cblock = infer_cblock(&mq->cache_pool, e); |
f2836352 JT |
809 | } |
810 | ||
811 | static int no_entry_found(struct mq_policy *mq, dm_oblock_t oblock, | |
812 | bool can_migrate, bool discarded_oblock, | |
813 | int data_dir, struct policy_result *result) | |
814 | { | |
78e03d69 | 815 | if (adjusted_promote_threshold(mq, discarded_oblock, data_dir) <= 1) { |
f2836352 JT |
816 | if (can_migrate) |
817 | insert_in_cache(mq, oblock, result); | |
818 | else | |
819 | return -EWOULDBLOCK; | |
820 | } else { | |
821 | insert_in_pre_cache(mq, oblock); | |
822 | result->op = POLICY_MISS; | |
823 | } | |
824 | ||
825 | return 0; | |
826 | } | |
827 | ||
828 | /* | |
829 | * Looks the oblock up in the hash table, then decides whether to put in | |
830 | * pre_cache, or cache etc. | |
831 | */ | |
832 | static int map(struct mq_policy *mq, dm_oblock_t oblock, | |
833 | bool can_migrate, bool discarded_oblock, | |
834 | int data_dir, struct policy_result *result) | |
835 | { | |
836 | int r = 0; | |
837 | struct entry *e = hash_lookup(mq, oblock); | |
838 | ||
633618e3 | 839 | if (e && in_cache(mq, e)) |
f2836352 | 840 | r = cache_entry_found(mq, e, result); |
633618e3 | 841 | |
f2836352 JT |
842 | else if (iot_pattern(&mq->tracker) == PATTERN_SEQUENTIAL) |
843 | result->op = POLICY_MISS; | |
633618e3 | 844 | |
f2836352 JT |
845 | else if (e) |
846 | r = pre_cache_entry_found(mq, e, can_migrate, discarded_oblock, | |
847 | data_dir, result); | |
633618e3 | 848 | |
f2836352 JT |
849 | else |
850 | r = no_entry_found(mq, oblock, can_migrate, discarded_oblock, | |
851 | data_dir, result); | |
852 | ||
853 | if (r == -EWOULDBLOCK) | |
854 | result->op = POLICY_MISS; | |
855 | ||
856 | return r; | |
857 | } | |
858 | ||
859 | /*----------------------------------------------------------------*/ | |
860 | ||
861 | /* | |
862 | * Public interface, via the policy struct. See dm-cache-policy.h for a | |
863 | * description of these. | |
864 | */ | |
865 | ||
866 | static struct mq_policy *to_mq_policy(struct dm_cache_policy *p) | |
867 | { | |
868 | return container_of(p, struct mq_policy, policy); | |
869 | } | |
870 | ||
871 | static void mq_destroy(struct dm_cache_policy *p) | |
872 | { | |
873 | struct mq_policy *mq = to_mq_policy(p); | |
874 | ||
14f398ca | 875 | vfree(mq->table); |
633618e3 JT |
876 | epool_exit(&mq->cache_pool); |
877 | epool_exit(&mq->pre_cache_pool); | |
f2836352 JT |
878 | kfree(mq); |
879 | } | |
880 | ||
881 | static void copy_tick(struct mq_policy *mq) | |
882 | { | |
883 | unsigned long flags; | |
884 | ||
885 | spin_lock_irqsave(&mq->tick_lock, flags); | |
886 | mq->tick = mq->tick_protected; | |
887 | spin_unlock_irqrestore(&mq->tick_lock, flags); | |
888 | } | |
889 | ||
890 | static int mq_map(struct dm_cache_policy *p, dm_oblock_t oblock, | |
891 | bool can_block, bool can_migrate, bool discarded_oblock, | |
892 | struct bio *bio, struct policy_result *result) | |
893 | { | |
894 | int r; | |
895 | struct mq_policy *mq = to_mq_policy(p); | |
896 | ||
897 | result->op = POLICY_MISS; | |
898 | ||
899 | if (can_block) | |
900 | mutex_lock(&mq->lock); | |
901 | else if (!mutex_trylock(&mq->lock)) | |
902 | return -EWOULDBLOCK; | |
903 | ||
904 | copy_tick(mq); | |
905 | ||
906 | iot_examine_bio(&mq->tracker, bio); | |
907 | r = map(mq, oblock, can_migrate, discarded_oblock, | |
908 | bio_data_dir(bio), result); | |
909 | ||
910 | mutex_unlock(&mq->lock); | |
911 | ||
912 | return r; | |
913 | } | |
914 | ||
915 | static int mq_lookup(struct dm_cache_policy *p, dm_oblock_t oblock, dm_cblock_t *cblock) | |
916 | { | |
917 | int r; | |
918 | struct mq_policy *mq = to_mq_policy(p); | |
919 | struct entry *e; | |
920 | ||
921 | if (!mutex_trylock(&mq->lock)) | |
922 | return -EWOULDBLOCK; | |
923 | ||
924 | e = hash_lookup(mq, oblock); | |
633618e3 JT |
925 | if (e && in_cache(mq, e)) { |
926 | *cblock = infer_cblock(&mq->cache_pool, e); | |
f2836352 JT |
927 | r = 0; |
928 | } else | |
929 | r = -ENOENT; | |
930 | ||
931 | mutex_unlock(&mq->lock); | |
932 | ||
933 | return r; | |
934 | } | |
935 | ||
633618e3 | 936 | static void __mq_set_clear_dirty(struct mq_policy *mq, dm_oblock_t oblock, bool set) |
01911c19 | 937 | { |
01911c19 JT |
938 | struct entry *e; |
939 | ||
01911c19 | 940 | e = hash_lookup(mq, oblock); |
633618e3 | 941 | BUG_ON(!e || !in_cache(mq, e)); |
01911c19 | 942 | |
633618e3 JT |
943 | del(mq, e); |
944 | e->dirty = set; | |
945 | push(mq, e); | |
01911c19 JT |
946 | } |
947 | ||
948 | static void mq_set_dirty(struct dm_cache_policy *p, dm_oblock_t oblock) | |
949 | { | |
633618e3 JT |
950 | struct mq_policy *mq = to_mq_policy(p); |
951 | ||
952 | mutex_lock(&mq->lock); | |
953 | __mq_set_clear_dirty(mq, oblock, true); | |
954 | mutex_unlock(&mq->lock); | |
01911c19 JT |
955 | } |
956 | ||
957 | static void mq_clear_dirty(struct dm_cache_policy *p, dm_oblock_t oblock) | |
958 | { | |
633618e3 JT |
959 | struct mq_policy *mq = to_mq_policy(p); |
960 | ||
961 | mutex_lock(&mq->lock); | |
962 | __mq_set_clear_dirty(mq, oblock, false); | |
963 | mutex_unlock(&mq->lock); | |
01911c19 JT |
964 | } |
965 | ||
f2836352 JT |
966 | static int mq_load_mapping(struct dm_cache_policy *p, |
967 | dm_oblock_t oblock, dm_cblock_t cblock, | |
968 | uint32_t hint, bool hint_valid) | |
969 | { | |
970 | struct mq_policy *mq = to_mq_policy(p); | |
971 | struct entry *e; | |
972 | ||
633618e3 | 973 | e = alloc_particular_entry(&mq->cache_pool, cblock); |
f2836352 | 974 | e->oblock = oblock; |
01911c19 | 975 | e->dirty = false; /* this gets corrected in a minute */ |
f2836352 JT |
976 | e->hit_count = hint_valid ? hint : 1; |
977 | e->generation = mq->generation; | |
978 | push(mq, e); | |
979 | ||
980 | return 0; | |
981 | } | |
982 | ||
633618e3 JT |
983 | static int mq_save_hints(struct mq_policy *mq, struct queue *q, |
984 | policy_walk_fn fn, void *context) | |
985 | { | |
986 | int r; | |
987 | unsigned level; | |
988 | struct entry *e; | |
989 | ||
990 | for (level = 0; level < NR_QUEUE_LEVELS; level++) | |
991 | list_for_each_entry(e, q->qs + level, list) { | |
992 | r = fn(context, infer_cblock(&mq->cache_pool, e), | |
993 | e->oblock, e->hit_count); | |
994 | if (r) | |
995 | return r; | |
996 | } | |
997 | ||
998 | return 0; | |
999 | } | |
1000 | ||
f2836352 JT |
1001 | static int mq_walk_mappings(struct dm_cache_policy *p, policy_walk_fn fn, |
1002 | void *context) | |
1003 | { | |
1004 | struct mq_policy *mq = to_mq_policy(p); | |
1005 | int r = 0; | |
f2836352 JT |
1006 | |
1007 | mutex_lock(&mq->lock); | |
1008 | ||
633618e3 JT |
1009 | r = mq_save_hints(mq, &mq->cache_clean, fn, context); |
1010 | if (!r) | |
1011 | r = mq_save_hints(mq, &mq->cache_dirty, fn, context); | |
f2836352 | 1012 | |
f2836352 JT |
1013 | mutex_unlock(&mq->lock); |
1014 | ||
1015 | return r; | |
1016 | } | |
1017 | ||
633618e3 | 1018 | static void __remove_mapping(struct mq_policy *mq, dm_oblock_t oblock) |
f2836352 | 1019 | { |
b936bf8b GU |
1020 | struct entry *e; |
1021 | ||
b936bf8b | 1022 | e = hash_lookup(mq, oblock); |
633618e3 | 1023 | BUG_ON(!e || !in_cache(mq, e)); |
f2836352 JT |
1024 | |
1025 | del(mq, e); | |
633618e3 JT |
1026 | free_entry(&mq->cache_pool, e); |
1027 | } | |
1028 | ||
1029 | static void mq_remove_mapping(struct dm_cache_policy *p, dm_oblock_t oblock) | |
1030 | { | |
1031 | struct mq_policy *mq = to_mq_policy(p); | |
f2836352 | 1032 | |
633618e3 JT |
1033 | mutex_lock(&mq->lock); |
1034 | __remove_mapping(mq, oblock); | |
f2836352 JT |
1035 | mutex_unlock(&mq->lock); |
1036 | } | |
1037 | ||
532906aa JT |
1038 | static int __remove_cblock(struct mq_policy *mq, dm_cblock_t cblock) |
1039 | { | |
1040 | struct entry *e = epool_find(&mq->cache_pool, cblock); | |
1041 | ||
1042 | if (!e) | |
1043 | return -ENODATA; | |
1044 | ||
1045 | del(mq, e); | |
1046 | free_entry(&mq->cache_pool, e); | |
1047 | ||
1048 | return 0; | |
1049 | } | |
1050 | ||
1051 | static int mq_remove_cblock(struct dm_cache_policy *p, dm_cblock_t cblock) | |
1052 | { | |
1053 | int r; | |
1054 | struct mq_policy *mq = to_mq_policy(p); | |
1055 | ||
1056 | mutex_lock(&mq->lock); | |
1057 | r = __remove_cblock(mq, cblock); | |
1058 | mutex_unlock(&mq->lock); | |
1059 | ||
1060 | return r; | |
1061 | } | |
1062 | ||
01911c19 JT |
1063 | static int __mq_writeback_work(struct mq_policy *mq, dm_oblock_t *oblock, |
1064 | dm_cblock_t *cblock) | |
1065 | { | |
1066 | struct entry *e = pop(mq, &mq->cache_dirty); | |
1067 | ||
1068 | if (!e) | |
1069 | return -ENODATA; | |
1070 | ||
1071 | *oblock = e->oblock; | |
633618e3 | 1072 | *cblock = infer_cblock(&mq->cache_pool, e); |
01911c19 JT |
1073 | e->dirty = false; |
1074 | push(mq, e); | |
1075 | ||
1076 | return 0; | |
1077 | } | |
1078 | ||
1079 | static int mq_writeback_work(struct dm_cache_policy *p, dm_oblock_t *oblock, | |
1080 | dm_cblock_t *cblock) | |
1081 | { | |
1082 | int r; | |
1083 | struct mq_policy *mq = to_mq_policy(p); | |
1084 | ||
1085 | mutex_lock(&mq->lock); | |
1086 | r = __mq_writeback_work(mq, oblock, cblock); | |
1087 | mutex_unlock(&mq->lock); | |
1088 | ||
1089 | return r; | |
1090 | } | |
1091 | ||
633618e3 JT |
1092 | static void __force_mapping(struct mq_policy *mq, |
1093 | dm_oblock_t current_oblock, dm_oblock_t new_oblock) | |
f2836352 JT |
1094 | { |
1095 | struct entry *e = hash_lookup(mq, current_oblock); | |
1096 | ||
633618e3 JT |
1097 | if (e && in_cache(mq, e)) { |
1098 | del(mq, e); | |
1099 | e->oblock = new_oblock; | |
1100 | e->dirty = true; | |
1101 | push(mq, e); | |
1102 | } | |
f2836352 JT |
1103 | } |
1104 | ||
1105 | static void mq_force_mapping(struct dm_cache_policy *p, | |
1106 | dm_oblock_t current_oblock, dm_oblock_t new_oblock) | |
1107 | { | |
1108 | struct mq_policy *mq = to_mq_policy(p); | |
1109 | ||
1110 | mutex_lock(&mq->lock); | |
633618e3 | 1111 | __force_mapping(mq, current_oblock, new_oblock); |
f2836352 JT |
1112 | mutex_unlock(&mq->lock); |
1113 | } | |
1114 | ||
1115 | static dm_cblock_t mq_residency(struct dm_cache_policy *p) | |
1116 | { | |
99ba2ae4 | 1117 | dm_cblock_t r; |
f2836352 JT |
1118 | struct mq_policy *mq = to_mq_policy(p); |
1119 | ||
99ba2ae4 | 1120 | mutex_lock(&mq->lock); |
633618e3 | 1121 | r = to_cblock(mq->cache_pool.nr_allocated); |
99ba2ae4 JT |
1122 | mutex_unlock(&mq->lock); |
1123 | ||
1124 | return r; | |
f2836352 JT |
1125 | } |
1126 | ||
1127 | static void mq_tick(struct dm_cache_policy *p) | |
1128 | { | |
1129 | struct mq_policy *mq = to_mq_policy(p); | |
1130 | unsigned long flags; | |
1131 | ||
1132 | spin_lock_irqsave(&mq->tick_lock, flags); | |
1133 | mq->tick_protected++; | |
1134 | spin_unlock_irqrestore(&mq->tick_lock, flags); | |
1135 | } | |
1136 | ||
1137 | static int mq_set_config_value(struct dm_cache_policy *p, | |
1138 | const char *key, const char *value) | |
1139 | { | |
1140 | struct mq_policy *mq = to_mq_policy(p); | |
f2836352 JT |
1141 | unsigned long tmp; |
1142 | ||
f2836352 JT |
1143 | if (kstrtoul(value, 10, &tmp)) |
1144 | return -EINVAL; | |
1145 | ||
78e03d69 JT |
1146 | if (!strcasecmp(key, "random_threshold")) { |
1147 | mq->tracker.thresholds[PATTERN_RANDOM] = tmp; | |
1148 | ||
1149 | } else if (!strcasecmp(key, "sequential_threshold")) { | |
1150 | mq->tracker.thresholds[PATTERN_SEQUENTIAL] = tmp; | |
1151 | ||
1152 | } else if (!strcasecmp(key, "discard_promote_adjustment")) | |
1153 | mq->discard_promote_adjustment = tmp; | |
1154 | ||
1155 | else if (!strcasecmp(key, "read_promote_adjustment")) | |
1156 | mq->read_promote_adjustment = tmp; | |
1157 | ||
1158 | else if (!strcasecmp(key, "write_promote_adjustment")) | |
1159 | mq->write_promote_adjustment = tmp; | |
1160 | ||
1161 | else | |
1162 | return -EINVAL; | |
f2836352 JT |
1163 | |
1164 | return 0; | |
1165 | } | |
1166 | ||
1167 | static int mq_emit_config_values(struct dm_cache_policy *p, char *result, unsigned maxlen) | |
1168 | { | |
1169 | ssize_t sz = 0; | |
1170 | struct mq_policy *mq = to_mq_policy(p); | |
1171 | ||
78e03d69 JT |
1172 | DMEMIT("10 random_threshold %u " |
1173 | "sequential_threshold %u " | |
1174 | "discard_promote_adjustment %u " | |
1175 | "read_promote_adjustment %u " | |
1176 | "write_promote_adjustment %u", | |
f2836352 | 1177 | mq->tracker.thresholds[PATTERN_RANDOM], |
78e03d69 JT |
1178 | mq->tracker.thresholds[PATTERN_SEQUENTIAL], |
1179 | mq->discard_promote_adjustment, | |
1180 | mq->read_promote_adjustment, | |
1181 | mq->write_promote_adjustment); | |
f2836352 JT |
1182 | |
1183 | return 0; | |
1184 | } | |
1185 | ||
1186 | /* Init the policy plugin interface function pointers. */ | |
1187 | static void init_policy_functions(struct mq_policy *mq) | |
1188 | { | |
1189 | mq->policy.destroy = mq_destroy; | |
1190 | mq->policy.map = mq_map; | |
1191 | mq->policy.lookup = mq_lookup; | |
01911c19 JT |
1192 | mq->policy.set_dirty = mq_set_dirty; |
1193 | mq->policy.clear_dirty = mq_clear_dirty; | |
f2836352 JT |
1194 | mq->policy.load_mapping = mq_load_mapping; |
1195 | mq->policy.walk_mappings = mq_walk_mappings; | |
1196 | mq->policy.remove_mapping = mq_remove_mapping; | |
532906aa | 1197 | mq->policy.remove_cblock = mq_remove_cblock; |
01911c19 | 1198 | mq->policy.writeback_work = mq_writeback_work; |
f2836352 JT |
1199 | mq->policy.force_mapping = mq_force_mapping; |
1200 | mq->policy.residency = mq_residency; | |
1201 | mq->policy.tick = mq_tick; | |
1202 | mq->policy.emit_config_values = mq_emit_config_values; | |
1203 | mq->policy.set_config_value = mq_set_config_value; | |
1204 | } | |
1205 | ||
1206 | static struct dm_cache_policy *mq_create(dm_cblock_t cache_size, | |
1207 | sector_t origin_size, | |
1208 | sector_t cache_block_size) | |
1209 | { | |
f2836352 JT |
1210 | struct mq_policy *mq = kzalloc(sizeof(*mq), GFP_KERNEL); |
1211 | ||
1212 | if (!mq) | |
1213 | return NULL; | |
1214 | ||
1215 | init_policy_functions(mq); | |
1216 | iot_init(&mq->tracker, SEQUENTIAL_THRESHOLD_DEFAULT, RANDOM_THRESHOLD_DEFAULT); | |
f2836352 | 1217 | mq->cache_size = cache_size; |
633618e3 JT |
1218 | |
1219 | if (epool_init(&mq->pre_cache_pool, from_cblock(cache_size))) { | |
1220 | DMERR("couldn't initialize pool of pre-cache entries"); | |
1221 | goto bad_pre_cache_init; | |
1222 | } | |
1223 | ||
1224 | if (epool_init(&mq->cache_pool, from_cblock(cache_size))) { | |
1225 | DMERR("couldn't initialize pool of cache entries"); | |
1226 | goto bad_cache_init; | |
1227 | } | |
1228 | ||
f2836352 JT |
1229 | mq->tick_protected = 0; |
1230 | mq->tick = 0; | |
1231 | mq->hit_count = 0; | |
1232 | mq->generation = 0; | |
1233 | mq->promote_threshold = 0; | |
78e03d69 JT |
1234 | mq->discard_promote_adjustment = DEFAULT_DISCARD_PROMOTE_ADJUSTMENT; |
1235 | mq->read_promote_adjustment = DEFAULT_READ_PROMOTE_ADJUSTMENT; | |
1236 | mq->write_promote_adjustment = DEFAULT_WRITE_PROMOTE_ADJUSTMENT; | |
f2836352 JT |
1237 | mutex_init(&mq->lock); |
1238 | spin_lock_init(&mq->tick_lock); | |
f2836352 JT |
1239 | |
1240 | queue_init(&mq->pre_cache); | |
01911c19 JT |
1241 | queue_init(&mq->cache_clean); |
1242 | queue_init(&mq->cache_dirty); | |
1243 | ||
f2836352 JT |
1244 | mq->generation_period = max((unsigned) from_cblock(cache_size), 1024U); |
1245 | ||
f2836352 JT |
1246 | mq->nr_buckets = next_power(from_cblock(cache_size) / 2, 16); |
1247 | mq->hash_bits = ffs(mq->nr_buckets) - 1; | |
14f398ca | 1248 | mq->table = vzalloc(sizeof(*mq->table) * mq->nr_buckets); |
f2836352 JT |
1249 | if (!mq->table) |
1250 | goto bad_alloc_table; | |
1251 | ||
f2836352 JT |
1252 | return &mq->policy; |
1253 | ||
f2836352 | 1254 | bad_alloc_table: |
633618e3 JT |
1255 | epool_exit(&mq->cache_pool); |
1256 | bad_cache_init: | |
1257 | epool_exit(&mq->pre_cache_pool); | |
1258 | bad_pre_cache_init: | |
f2836352 JT |
1259 | kfree(mq); |
1260 | ||
1261 | return NULL; | |
1262 | } | |
1263 | ||
1264 | /*----------------------------------------------------------------*/ | |
1265 | ||
1266 | static struct dm_cache_policy_type mq_policy_type = { | |
1267 | .name = "mq", | |
78e03d69 | 1268 | .version = {1, 2, 0}, |
f2836352 JT |
1269 | .hint_size = 4, |
1270 | .owner = THIS_MODULE, | |
1271 | .create = mq_create | |
1272 | }; | |
1273 | ||
1274 | static struct dm_cache_policy_type default_policy_type = { | |
1275 | .name = "default", | |
78e03d69 | 1276 | .version = {1, 2, 0}, |
f2836352 JT |
1277 | .hint_size = 4, |
1278 | .owner = THIS_MODULE, | |
2e68c4e6 MS |
1279 | .create = mq_create, |
1280 | .real = &mq_policy_type | |
f2836352 JT |
1281 | }; |
1282 | ||
1283 | static int __init mq_init(void) | |
1284 | { | |
1285 | int r; | |
1286 | ||
1287 | mq_entry_cache = kmem_cache_create("dm_mq_policy_cache_entry", | |
1288 | sizeof(struct entry), | |
1289 | __alignof__(struct entry), | |
1290 | 0, NULL); | |
1291 | if (!mq_entry_cache) | |
1292 | goto bad; | |
1293 | ||
1294 | r = dm_cache_policy_register(&mq_policy_type); | |
1295 | if (r) { | |
1296 | DMERR("register failed %d", r); | |
1297 | goto bad_register_mq; | |
1298 | } | |
1299 | ||
1300 | r = dm_cache_policy_register(&default_policy_type); | |
1301 | if (!r) { | |
4e7f506f MS |
1302 | DMINFO("version %u.%u.%u loaded", |
1303 | mq_policy_type.version[0], | |
1304 | mq_policy_type.version[1], | |
1305 | mq_policy_type.version[2]); | |
f2836352 JT |
1306 | return 0; |
1307 | } | |
1308 | ||
1309 | DMERR("register failed (as default) %d", r); | |
1310 | ||
1311 | dm_cache_policy_unregister(&mq_policy_type); | |
1312 | bad_register_mq: | |
1313 | kmem_cache_destroy(mq_entry_cache); | |
1314 | bad: | |
1315 | return -ENOMEM; | |
1316 | } | |
1317 | ||
1318 | static void __exit mq_exit(void) | |
1319 | { | |
1320 | dm_cache_policy_unregister(&mq_policy_type); | |
1321 | dm_cache_policy_unregister(&default_policy_type); | |
1322 | ||
1323 | kmem_cache_destroy(mq_entry_cache); | |
1324 | } | |
1325 | ||
1326 | module_init(mq_init); | |
1327 | module_exit(mq_exit); | |
1328 | ||
1329 | MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); | |
1330 | MODULE_LICENSE("GPL"); | |
1331 | MODULE_DESCRIPTION("mq cache policy"); | |
1332 | ||
1333 | MODULE_ALIAS("dm-cache-default"); |