Commit | Line | Data |
---|---|---|
75bb4625 JA |
1 | /* |
2 | * Fast and scalable bitmap tagging variant. Uses sparser bitmaps spread | |
3 | * over multiple cachelines to avoid ping-pong between multiple submitters | |
4 | * or submitter and completer. Uses rolling wakeups to avoid falling of | |
5 | * the scaling cliff when we run out of tags and have to start putting | |
6 | * submitters to sleep. | |
7 | * | |
8 | * Uses active queue tracking to support fairer distribution of tags | |
9 | * between multiple submitters when a shared tag map is used. | |
10 | * | |
11 | * Copyright (C) 2013-2014 Jens Axboe | |
12 | */ | |
320ae51f JA |
13 | #include <linux/kernel.h> |
14 | #include <linux/module.h> | |
4bb659b1 | 15 | #include <linux/random.h> |
320ae51f JA |
16 | |
17 | #include <linux/blk-mq.h> | |
18 | #include "blk.h" | |
19 | #include "blk-mq.h" | |
20 | #include "blk-mq-tag.h" | |
21 | ||
4bb659b1 JA |
22 | static bool bt_has_free_tags(struct blk_mq_bitmap_tags *bt) |
23 | { | |
24 | int i; | |
25 | ||
26 | for (i = 0; i < bt->map_nr; i++) { | |
e93ecf60 | 27 | struct blk_align_bitmap *bm = &bt->map[i]; |
4bb659b1 JA |
28 | int ret; |
29 | ||
30 | ret = find_first_zero_bit(&bm->word, bm->depth); | |
31 | if (ret < bm->depth) | |
32 | return true; | |
33 | } | |
34 | ||
35 | return false; | |
320ae51f JA |
36 | } |
37 | ||
38 | bool blk_mq_has_free_tags(struct blk_mq_tags *tags) | |
39 | { | |
4bb659b1 JA |
40 | if (!tags) |
41 | return true; | |
42 | ||
43 | return bt_has_free_tags(&tags->bitmap_tags); | |
44 | } | |
45 | ||
8537b120 | 46 | static inline int bt_index_inc(int index) |
0d2602ca | 47 | { |
8537b120 AG |
48 | return (index + 1) & (BT_WAIT_QUEUES - 1); |
49 | } | |
50 | ||
51 | static inline void bt_index_atomic_inc(atomic_t *index) | |
52 | { | |
53 | int old = atomic_read(index); | |
54 | int new = bt_index_inc(old); | |
55 | atomic_cmpxchg(index, old, new); | |
0d2602ca JA |
56 | } |
57 | ||
58 | /* | |
59 | * If a previously inactive queue goes active, bump the active user count. | |
60 | */ | |
61 | bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx) | |
62 | { | |
63 | if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) && | |
64 | !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
65 | atomic_inc(&hctx->tags->active_queues); | |
66 | ||
67 | return true; | |
68 | } | |
69 | ||
70 | /* | |
aed3ea94 | 71 | * Wakeup all potentially sleeping on tags |
0d2602ca | 72 | */ |
aed3ea94 | 73 | void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool include_reserve) |
0d2602ca | 74 | { |
0d2602ca JA |
75 | struct blk_mq_bitmap_tags *bt; |
76 | int i, wake_index; | |
77 | ||
0d2602ca | 78 | bt = &tags->bitmap_tags; |
8537b120 | 79 | wake_index = atomic_read(&bt->wake_index); |
0d2602ca JA |
80 | for (i = 0; i < BT_WAIT_QUEUES; i++) { |
81 | struct bt_wait_state *bs = &bt->bs[wake_index]; | |
82 | ||
83 | if (waitqueue_active(&bs->wait)) | |
84 | wake_up(&bs->wait); | |
85 | ||
8537b120 | 86 | wake_index = bt_index_inc(wake_index); |
0d2602ca | 87 | } |
aed3ea94 JA |
88 | |
89 | if (include_reserve) { | |
90 | bt = &tags->breserved_tags; | |
91 | if (waitqueue_active(&bt->bs[0].wait)) | |
92 | wake_up(&bt->bs[0].wait); | |
93 | } | |
0d2602ca JA |
94 | } |
95 | ||
e3a2b3f9 JA |
96 | /* |
97 | * If a previously busy queue goes inactive, potential waiters could now | |
98 | * be allowed to queue. Wake them up and check. | |
99 | */ | |
100 | void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx) | |
101 | { | |
102 | struct blk_mq_tags *tags = hctx->tags; | |
103 | ||
104 | if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
105 | return; | |
106 | ||
107 | atomic_dec(&tags->active_queues); | |
108 | ||
aed3ea94 | 109 | blk_mq_tag_wakeup_all(tags, false); |
e3a2b3f9 JA |
110 | } |
111 | ||
0d2602ca JA |
112 | /* |
113 | * For shared tag users, we track the number of currently active users | |
114 | * and attempt to provide a fair share of the tag depth for each of them. | |
115 | */ | |
116 | static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, | |
117 | struct blk_mq_bitmap_tags *bt) | |
118 | { | |
119 | unsigned int depth, users; | |
120 | ||
121 | if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_SHARED)) | |
122 | return true; | |
123 | if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
124 | return true; | |
125 | ||
126 | /* | |
127 | * Don't try dividing an ant | |
128 | */ | |
129 | if (bt->depth == 1) | |
130 | return true; | |
131 | ||
132 | users = atomic_read(&hctx->tags->active_queues); | |
133 | if (!users) | |
134 | return true; | |
135 | ||
136 | /* | |
137 | * Allow at least some tags | |
138 | */ | |
139 | depth = max((bt->depth + users - 1) / users, 4U); | |
140 | return atomic_read(&hctx->nr_active) < depth; | |
141 | } | |
142 | ||
24391c0d SL |
143 | static int __bt_get_word(struct blk_align_bitmap *bm, unsigned int last_tag, |
144 | bool nowrap) | |
4bb659b1 | 145 | { |
0bf36498 JA |
146 | int tag, org_last_tag = last_tag; |
147 | ||
148 | while (1) { | |
149 | tag = find_next_zero_bit(&bm->word, bm->depth, last_tag); | |
150 | if (unlikely(tag >= bm->depth)) { | |
4bb659b1 | 151 | /* |
0bf36498 JA |
152 | * We started with an offset, and we didn't reset the |
153 | * offset to 0 in a failure case, so start from 0 to | |
4bb659b1 JA |
154 | * exhaust the map. |
155 | */ | |
24391c0d | 156 | if (org_last_tag && last_tag && !nowrap) { |
0bf36498 JA |
157 | last_tag = org_last_tag = 0; |
158 | continue; | |
4bb659b1 JA |
159 | } |
160 | return -1; | |
161 | } | |
0bf36498 JA |
162 | |
163 | if (!test_and_set_bit(tag, &bm->word)) | |
164 | break; | |
165 | ||
4bb659b1 | 166 | last_tag = tag + 1; |
0bf36498 JA |
167 | if (last_tag >= bm->depth - 1) |
168 | last_tag = 0; | |
169 | } | |
4bb659b1 JA |
170 | |
171 | return tag; | |
172 | } | |
173 | ||
24391c0d SL |
174 | #define BT_ALLOC_RR(tags) (tags->alloc_policy == BLK_TAG_ALLOC_RR) |
175 | ||
4bb659b1 JA |
176 | /* |
177 | * Straight forward bitmap tag implementation, where each bit is a tag | |
178 | * (cleared == free, and set == busy). The small twist is using per-cpu | |
179 | * last_tag caches, which blk-mq stores in the blk_mq_ctx software queue | |
180 | * contexts. This enables us to drastically limit the space searched, | |
181 | * without dirtying an extra shared cacheline like we would if we stored | |
182 | * the cache value inside the shared blk_mq_bitmap_tags structure. On top | |
183 | * of that, each word of tags is in a separate cacheline. This means that | |
184 | * multiple users will tend to stick to different cachelines, at least | |
185 | * until the map is exhausted. | |
186 | */ | |
0d2602ca | 187 | static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt, |
24391c0d | 188 | unsigned int *tag_cache, struct blk_mq_tags *tags) |
4bb659b1 JA |
189 | { |
190 | unsigned int last_tag, org_last_tag; | |
191 | int index, i, tag; | |
192 | ||
0d2602ca JA |
193 | if (!hctx_may_queue(hctx, bt)) |
194 | return -1; | |
195 | ||
4bb659b1 | 196 | last_tag = org_last_tag = *tag_cache; |
59d13bf5 | 197 | index = TAG_TO_INDEX(bt, last_tag); |
4bb659b1 JA |
198 | |
199 | for (i = 0; i < bt->map_nr; i++) { | |
24391c0d SL |
200 | tag = __bt_get_word(&bt->map[index], TAG_TO_BIT(bt, last_tag), |
201 | BT_ALLOC_RR(tags)); | |
4bb659b1 | 202 | if (tag != -1) { |
59d13bf5 | 203 | tag += (index << bt->bits_per_word); |
4bb659b1 JA |
204 | goto done; |
205 | } | |
206 | ||
0bf36498 JA |
207 | /* |
208 | * Jump to next index, and reset the last tag to be the | |
209 | * first tag of that index | |
210 | */ | |
211 | index++; | |
212 | last_tag = (index << bt->bits_per_word); | |
213 | ||
214 | if (index >= bt->map_nr) { | |
4bb659b1 | 215 | index = 0; |
0bf36498 JA |
216 | last_tag = 0; |
217 | } | |
4bb659b1 JA |
218 | } |
219 | ||
220 | *tag_cache = 0; | |
221 | return -1; | |
222 | ||
223 | /* | |
224 | * Only update the cache from the allocation path, if we ended | |
225 | * up using the specific cached tag. | |
226 | */ | |
227 | done: | |
24391c0d | 228 | if (tag == org_last_tag || unlikely(BT_ALLOC_RR(tags))) { |
4bb659b1 JA |
229 | last_tag = tag + 1; |
230 | if (last_tag >= bt->depth - 1) | |
231 | last_tag = 0; | |
232 | ||
233 | *tag_cache = last_tag; | |
234 | } | |
235 | ||
236 | return tag; | |
237 | } | |
238 | ||
4bb659b1 JA |
239 | static struct bt_wait_state *bt_wait_ptr(struct blk_mq_bitmap_tags *bt, |
240 | struct blk_mq_hw_ctx *hctx) | |
241 | { | |
242 | struct bt_wait_state *bs; | |
8537b120 | 243 | int wait_index; |
4bb659b1 JA |
244 | |
245 | if (!hctx) | |
246 | return &bt->bs[0]; | |
247 | ||
8537b120 AG |
248 | wait_index = atomic_read(&hctx->wait_index); |
249 | bs = &bt->bs[wait_index]; | |
250 | bt_index_atomic_inc(&hctx->wait_index); | |
4bb659b1 | 251 | return bs; |
320ae51f JA |
252 | } |
253 | ||
cb96a42c ML |
254 | static int bt_get(struct blk_mq_alloc_data *data, |
255 | struct blk_mq_bitmap_tags *bt, | |
256 | struct blk_mq_hw_ctx *hctx, | |
24391c0d | 257 | unsigned int *last_tag, struct blk_mq_tags *tags) |
320ae51f | 258 | { |
4bb659b1 JA |
259 | struct bt_wait_state *bs; |
260 | DEFINE_WAIT(wait); | |
320ae51f JA |
261 | int tag; |
262 | ||
24391c0d | 263 | tag = __bt_get(hctx, bt, last_tag, tags); |
4bb659b1 JA |
264 | if (tag != -1) |
265 | return tag; | |
266 | ||
cb96a42c | 267 | if (!(data->gfp & __GFP_WAIT)) |
4bb659b1 JA |
268 | return -1; |
269 | ||
35d37c66 | 270 | bs = bt_wait_ptr(bt, hctx); |
4bb659b1 | 271 | do { |
4bb659b1 JA |
272 | prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE); |
273 | ||
24391c0d | 274 | tag = __bt_get(hctx, bt, last_tag, tags); |
4bb659b1 JA |
275 | if (tag != -1) |
276 | break; | |
277 | ||
b3223207 BVA |
278 | /* |
279 | * We're out of tags on this hardware queue, kick any | |
280 | * pending IO submits before going to sleep waiting for | |
bc188d81 SB |
281 | * some to complete. Note that hctx can be NULL here for |
282 | * reserved tag allocation. | |
b3223207 | 283 | */ |
bc188d81 SB |
284 | if (hctx) |
285 | blk_mq_run_hw_queue(hctx, false); | |
b3223207 | 286 | |
080ff351 JA |
287 | /* |
288 | * Retry tag allocation after running the hardware queue, | |
289 | * as running the queue may also have found completions. | |
290 | */ | |
24391c0d | 291 | tag = __bt_get(hctx, bt, last_tag, tags); |
080ff351 JA |
292 | if (tag != -1) |
293 | break; | |
294 | ||
cb96a42c ML |
295 | blk_mq_put_ctx(data->ctx); |
296 | ||
4bb659b1 | 297 | io_schedule(); |
cb96a42c ML |
298 | |
299 | data->ctx = blk_mq_get_ctx(data->q); | |
300 | data->hctx = data->q->mq_ops->map_queue(data->q, | |
301 | data->ctx->cpu); | |
302 | if (data->reserved) { | |
303 | bt = &data->hctx->tags->breserved_tags; | |
304 | } else { | |
305 | last_tag = &data->ctx->last_tag; | |
306 | hctx = data->hctx; | |
307 | bt = &hctx->tags->bitmap_tags; | |
308 | } | |
35d37c66 JA |
309 | finish_wait(&bs->wait, &wait); |
310 | bs = bt_wait_ptr(bt, hctx); | |
4bb659b1 JA |
311 | } while (1); |
312 | ||
313 | finish_wait(&bs->wait, &wait); | |
314 | return tag; | |
315 | } | |
316 | ||
cb96a42c | 317 | static unsigned int __blk_mq_get_tag(struct blk_mq_alloc_data *data) |
4bb659b1 JA |
318 | { |
319 | int tag; | |
320 | ||
cb96a42c | 321 | tag = bt_get(data, &data->hctx->tags->bitmap_tags, data->hctx, |
24391c0d | 322 | &data->ctx->last_tag, data->hctx->tags); |
4bb659b1 | 323 | if (tag >= 0) |
cb96a42c | 324 | return tag + data->hctx->tags->nr_reserved_tags; |
4bb659b1 JA |
325 | |
326 | return BLK_MQ_TAG_FAIL; | |
320ae51f JA |
327 | } |
328 | ||
cb96a42c | 329 | static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_alloc_data *data) |
320ae51f | 330 | { |
4bb659b1 | 331 | int tag, zero = 0; |
320ae51f | 332 | |
cb96a42c | 333 | if (unlikely(!data->hctx->tags->nr_reserved_tags)) { |
320ae51f JA |
334 | WARN_ON_ONCE(1); |
335 | return BLK_MQ_TAG_FAIL; | |
336 | } | |
337 | ||
24391c0d SL |
338 | tag = bt_get(data, &data->hctx->tags->breserved_tags, NULL, &zero, |
339 | data->hctx->tags); | |
320ae51f JA |
340 | if (tag < 0) |
341 | return BLK_MQ_TAG_FAIL; | |
4bb659b1 | 342 | |
320ae51f JA |
343 | return tag; |
344 | } | |
345 | ||
cb96a42c | 346 | unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) |
320ae51f | 347 | { |
cb96a42c ML |
348 | if (!data->reserved) |
349 | return __blk_mq_get_tag(data); | |
320ae51f | 350 | |
cb96a42c | 351 | return __blk_mq_get_reserved_tag(data); |
320ae51f JA |
352 | } |
353 | ||
4bb659b1 JA |
354 | static struct bt_wait_state *bt_wake_ptr(struct blk_mq_bitmap_tags *bt) |
355 | { | |
356 | int i, wake_index; | |
357 | ||
8537b120 | 358 | wake_index = atomic_read(&bt->wake_index); |
4bb659b1 JA |
359 | for (i = 0; i < BT_WAIT_QUEUES; i++) { |
360 | struct bt_wait_state *bs = &bt->bs[wake_index]; | |
361 | ||
362 | if (waitqueue_active(&bs->wait)) { | |
8537b120 AG |
363 | int o = atomic_read(&bt->wake_index); |
364 | if (wake_index != o) | |
365 | atomic_cmpxchg(&bt->wake_index, o, wake_index); | |
4bb659b1 JA |
366 | |
367 | return bs; | |
368 | } | |
369 | ||
8537b120 | 370 | wake_index = bt_index_inc(wake_index); |
4bb659b1 JA |
371 | } |
372 | ||
373 | return NULL; | |
374 | } | |
375 | ||
376 | static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag) | |
377 | { | |
59d13bf5 | 378 | const int index = TAG_TO_INDEX(bt, tag); |
4bb659b1 | 379 | struct bt_wait_state *bs; |
2971c35f | 380 | int wait_cnt; |
4bb659b1 | 381 | |
c38d185d BVA |
382 | clear_bit(TAG_TO_BIT(bt, tag), &bt->map[index].word); |
383 | ||
384 | /* Ensure that the wait list checks occur after clear_bit(). */ | |
385 | smp_mb(); | |
4bb659b1 JA |
386 | |
387 | bs = bt_wake_ptr(bt); | |
2971c35f AG |
388 | if (!bs) |
389 | return; | |
390 | ||
391 | wait_cnt = atomic_dec_return(&bs->wait_cnt); | |
9d8f0bcc BVA |
392 | if (unlikely(wait_cnt < 0)) |
393 | wait_cnt = atomic_inc_return(&bs->wait_cnt); | |
2971c35f | 394 | if (wait_cnt == 0) { |
2971c35f | 395 | atomic_add(bt->wake_cnt, &bs->wait_cnt); |
8537b120 | 396 | bt_index_atomic_inc(&bt->wake_index); |
4bb659b1 JA |
397 | wake_up(&bs->wait); |
398 | } | |
399 | } | |
400 | ||
0d2602ca | 401 | void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, unsigned int tag, |
4bb659b1 | 402 | unsigned int *last_tag) |
320ae51f | 403 | { |
0d2602ca JA |
404 | struct blk_mq_tags *tags = hctx->tags; |
405 | ||
4bb659b1 JA |
406 | if (tag >= tags->nr_reserved_tags) { |
407 | const int real_tag = tag - tags->nr_reserved_tags; | |
408 | ||
70114c39 JA |
409 | BUG_ON(real_tag >= tags->nr_tags); |
410 | bt_clear_tag(&tags->bitmap_tags, real_tag); | |
24391c0d SL |
411 | if (likely(tags->alloc_policy == BLK_TAG_ALLOC_FIFO)) |
412 | *last_tag = real_tag; | |
70114c39 JA |
413 | } else { |
414 | BUG_ON(tag >= tags->nr_reserved_tags); | |
415 | bt_clear_tag(&tags->breserved_tags, tag); | |
416 | } | |
320ae51f JA |
417 | } |
418 | ||
81481eb4 CH |
419 | static void bt_for_each(struct blk_mq_hw_ctx *hctx, |
420 | struct blk_mq_bitmap_tags *bt, unsigned int off, | |
421 | busy_iter_fn *fn, void *data, bool reserved) | |
320ae51f | 422 | { |
81481eb4 CH |
423 | struct request *rq; |
424 | int bit, i; | |
4bb659b1 JA |
425 | |
426 | for (i = 0; i < bt->map_nr; i++) { | |
e93ecf60 | 427 | struct blk_align_bitmap *bm = &bt->map[i]; |
4bb659b1 | 428 | |
81481eb4 CH |
429 | for (bit = find_first_bit(&bm->word, bm->depth); |
430 | bit < bm->depth; | |
431 | bit = find_next_bit(&bm->word, bm->depth, bit + 1)) { | |
432 | rq = blk_mq_tag_to_rq(hctx->tags, off + bit); | |
433 | if (rq->q == hctx->queue) | |
434 | fn(hctx, rq, data, reserved); | |
435 | } | |
4bb659b1 | 436 | |
59d13bf5 | 437 | off += (1 << bt->bits_per_word); |
4bb659b1 | 438 | } |
320ae51f JA |
439 | } |
440 | ||
f26cdc85 KB |
441 | static void bt_tags_for_each(struct blk_mq_tags *tags, |
442 | struct blk_mq_bitmap_tags *bt, unsigned int off, | |
443 | busy_tag_iter_fn *fn, void *data, bool reserved) | |
444 | { | |
445 | struct request *rq; | |
446 | int bit, i; | |
447 | ||
448 | if (!tags->rqs) | |
449 | return; | |
450 | for (i = 0; i < bt->map_nr; i++) { | |
451 | struct blk_align_bitmap *bm = &bt->map[i]; | |
452 | ||
453 | for (bit = find_first_bit(&bm->word, bm->depth); | |
454 | bit < bm->depth; | |
455 | bit = find_next_bit(&bm->word, bm->depth, bit + 1)) { | |
456 | rq = blk_mq_tag_to_rq(tags, off + bit); | |
457 | fn(rq, data, reserved); | |
458 | } | |
459 | ||
460 | off += (1 << bt->bits_per_word); | |
461 | } | |
462 | } | |
463 | ||
464 | void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn, | |
465 | void *priv) | |
466 | { | |
467 | if (tags->nr_reserved_tags) | |
468 | bt_tags_for_each(tags, &tags->breserved_tags, 0, fn, priv, true); | |
469 | bt_tags_for_each(tags, &tags->bitmap_tags, tags->nr_reserved_tags, fn, priv, | |
470 | false); | |
471 | } | |
472 | EXPORT_SYMBOL(blk_mq_all_tag_busy_iter); | |
473 | ||
81481eb4 CH |
474 | void blk_mq_tag_busy_iter(struct blk_mq_hw_ctx *hctx, busy_iter_fn *fn, |
475 | void *priv) | |
320ae51f | 476 | { |
81481eb4 | 477 | struct blk_mq_tags *tags = hctx->tags; |
320ae51f | 478 | |
320ae51f | 479 | if (tags->nr_reserved_tags) |
81481eb4 CH |
480 | bt_for_each(hctx, &tags->breserved_tags, 0, fn, priv, true); |
481 | bt_for_each(hctx, &tags->bitmap_tags, tags->nr_reserved_tags, fn, priv, | |
482 | false); | |
320ae51f | 483 | } |
edf866b3 | 484 | EXPORT_SYMBOL(blk_mq_tag_busy_iter); |
320ae51f | 485 | |
4bb659b1 JA |
486 | static unsigned int bt_unused_tags(struct blk_mq_bitmap_tags *bt) |
487 | { | |
488 | unsigned int i, used; | |
489 | ||
490 | for (i = 0, used = 0; i < bt->map_nr; i++) { | |
e93ecf60 | 491 | struct blk_align_bitmap *bm = &bt->map[i]; |
4bb659b1 JA |
492 | |
493 | used += bitmap_weight(&bm->word, bm->depth); | |
494 | } | |
495 | ||
496 | return bt->depth - used; | |
497 | } | |
498 | ||
e3a2b3f9 JA |
499 | static void bt_update_count(struct blk_mq_bitmap_tags *bt, |
500 | unsigned int depth) | |
501 | { | |
502 | unsigned int tags_per_word = 1U << bt->bits_per_word; | |
503 | unsigned int map_depth = depth; | |
504 | ||
505 | if (depth) { | |
506 | int i; | |
507 | ||
508 | for (i = 0; i < bt->map_nr; i++) { | |
509 | bt->map[i].depth = min(map_depth, tags_per_word); | |
510 | map_depth -= bt->map[i].depth; | |
511 | } | |
512 | } | |
513 | ||
514 | bt->wake_cnt = BT_WAIT_BATCH; | |
abab13b5 JA |
515 | if (bt->wake_cnt > depth / BT_WAIT_QUEUES) |
516 | bt->wake_cnt = max(1U, depth / BT_WAIT_QUEUES); | |
e3a2b3f9 JA |
517 | |
518 | bt->depth = depth; | |
519 | } | |
520 | ||
4bb659b1 JA |
521 | static int bt_alloc(struct blk_mq_bitmap_tags *bt, unsigned int depth, |
522 | int node, bool reserved) | |
523 | { | |
524 | int i; | |
525 | ||
59d13bf5 JA |
526 | bt->bits_per_word = ilog2(BITS_PER_LONG); |
527 | ||
4bb659b1 JA |
528 | /* |
529 | * Depth can be zero for reserved tags, that's not a failure | |
530 | * condition. | |
531 | */ | |
532 | if (depth) { | |
e3a2b3f9 | 533 | unsigned int nr, tags_per_word; |
59d13bf5 JA |
534 | |
535 | tags_per_word = (1 << bt->bits_per_word); | |
536 | ||
537 | /* | |
538 | * If the tag space is small, shrink the number of tags | |
539 | * per word so we spread over a few cachelines, at least. | |
540 | * If less than 4 tags, just forget about it, it's not | |
541 | * going to work optimally anyway. | |
542 | */ | |
543 | if (depth >= 4) { | |
544 | while (tags_per_word * 4 > depth) { | |
545 | bt->bits_per_word--; | |
546 | tags_per_word = (1 << bt->bits_per_word); | |
547 | } | |
548 | } | |
4bb659b1 | 549 | |
59d13bf5 | 550 | nr = ALIGN(depth, tags_per_word) / tags_per_word; |
e93ecf60 | 551 | bt->map = kzalloc_node(nr * sizeof(struct blk_align_bitmap), |
4bb659b1 JA |
552 | GFP_KERNEL, node); |
553 | if (!bt->map) | |
554 | return -ENOMEM; | |
555 | ||
556 | bt->map_nr = nr; | |
4bb659b1 JA |
557 | } |
558 | ||
559 | bt->bs = kzalloc(BT_WAIT_QUEUES * sizeof(*bt->bs), GFP_KERNEL); | |
560 | if (!bt->bs) { | |
561 | kfree(bt->map); | |
564e559f | 562 | bt->map = NULL; |
4bb659b1 JA |
563 | return -ENOMEM; |
564 | } | |
565 | ||
86fb5c56 AG |
566 | bt_update_count(bt, depth); |
567 | ||
568 | for (i = 0; i < BT_WAIT_QUEUES; i++) { | |
4bb659b1 | 569 | init_waitqueue_head(&bt->bs[i].wait); |
86fb5c56 AG |
570 | atomic_set(&bt->bs[i].wait_cnt, bt->wake_cnt); |
571 | } | |
4bb659b1 | 572 | |
4bb659b1 JA |
573 | return 0; |
574 | } | |
575 | ||
576 | static void bt_free(struct blk_mq_bitmap_tags *bt) | |
577 | { | |
578 | kfree(bt->map); | |
579 | kfree(bt->bs); | |
580 | } | |
581 | ||
582 | static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, | |
24391c0d | 583 | int node, int alloc_policy) |
4bb659b1 JA |
584 | { |
585 | unsigned int depth = tags->nr_tags - tags->nr_reserved_tags; | |
586 | ||
24391c0d SL |
587 | tags->alloc_policy = alloc_policy; |
588 | ||
4bb659b1 JA |
589 | if (bt_alloc(&tags->bitmap_tags, depth, node, false)) |
590 | goto enomem; | |
591 | if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, node, true)) | |
592 | goto enomem; | |
593 | ||
594 | return tags; | |
595 | enomem: | |
596 | bt_free(&tags->bitmap_tags); | |
597 | kfree(tags); | |
598 | return NULL; | |
599 | } | |
600 | ||
320ae51f | 601 | struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, |
24391c0d SL |
602 | unsigned int reserved_tags, |
603 | int node, int alloc_policy) | |
320ae51f | 604 | { |
320ae51f | 605 | struct blk_mq_tags *tags; |
320ae51f JA |
606 | |
607 | if (total_tags > BLK_MQ_TAG_MAX) { | |
608 | pr_err("blk-mq: tag depth too large\n"); | |
609 | return NULL; | |
610 | } | |
611 | ||
612 | tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node); | |
613 | if (!tags) | |
614 | return NULL; | |
615 | ||
f26cdc85 KB |
616 | if (!zalloc_cpumask_var(&tags->cpumask, GFP_KERNEL)) { |
617 | kfree(tags); | |
618 | return NULL; | |
619 | } | |
620 | ||
320ae51f JA |
621 | tags->nr_tags = total_tags; |
622 | tags->nr_reserved_tags = reserved_tags; | |
320ae51f | 623 | |
24391c0d | 624 | return blk_mq_init_bitmap_tags(tags, node, alloc_policy); |
320ae51f JA |
625 | } |
626 | ||
627 | void blk_mq_free_tags(struct blk_mq_tags *tags) | |
628 | { | |
4bb659b1 JA |
629 | bt_free(&tags->bitmap_tags); |
630 | bt_free(&tags->breserved_tags); | |
320ae51f JA |
631 | kfree(tags); |
632 | } | |
633 | ||
4bb659b1 JA |
634 | void blk_mq_tag_init_last_tag(struct blk_mq_tags *tags, unsigned int *tag) |
635 | { | |
636 | unsigned int depth = tags->nr_tags - tags->nr_reserved_tags; | |
637 | ||
9d3d21ae | 638 | *tag = prandom_u32() % depth; |
4bb659b1 JA |
639 | } |
640 | ||
e3a2b3f9 JA |
641 | int blk_mq_tag_update_depth(struct blk_mq_tags *tags, unsigned int tdepth) |
642 | { | |
643 | tdepth -= tags->nr_reserved_tags; | |
644 | if (tdepth > tags->nr_tags) | |
645 | return -EINVAL; | |
646 | ||
647 | /* | |
648 | * Don't need (or can't) update reserved tags here, they remain | |
649 | * static and should never need resizing. | |
650 | */ | |
651 | bt_update_count(&tags->bitmap_tags, tdepth); | |
aed3ea94 | 652 | blk_mq_tag_wakeup_all(tags, false); |
e3a2b3f9 JA |
653 | return 0; |
654 | } | |
655 | ||
205fb5f5 BVA |
656 | /** |
657 | * blk_mq_unique_tag() - return a tag that is unique queue-wide | |
658 | * @rq: request for which to compute a unique tag | |
659 | * | |
660 | * The tag field in struct request is unique per hardware queue but not over | |
661 | * all hardware queues. Hence this function that returns a tag with the | |
662 | * hardware context index in the upper bits and the per hardware queue tag in | |
663 | * the lower bits. | |
664 | * | |
665 | * Note: When called for a request that is queued on a non-multiqueue request | |
666 | * queue, the hardware context index is set to zero. | |
667 | */ | |
668 | u32 blk_mq_unique_tag(struct request *rq) | |
669 | { | |
670 | struct request_queue *q = rq->q; | |
671 | struct blk_mq_hw_ctx *hctx; | |
672 | int hwq = 0; | |
673 | ||
674 | if (q->mq_ops) { | |
675 | hctx = q->mq_ops->map_queue(q, rq->mq_ctx->cpu); | |
676 | hwq = hctx->queue_num; | |
677 | } | |
678 | ||
679 | return (hwq << BLK_MQ_UNIQUE_TAG_BITS) | | |
680 | (rq->tag & BLK_MQ_UNIQUE_TAG_MASK); | |
681 | } | |
682 | EXPORT_SYMBOL(blk_mq_unique_tag); | |
683 | ||
320ae51f JA |
684 | ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page) |
685 | { | |
686 | char *orig_page = page; | |
4bb659b1 | 687 | unsigned int free, res; |
320ae51f JA |
688 | |
689 | if (!tags) | |
690 | return 0; | |
691 | ||
59d13bf5 JA |
692 | page += sprintf(page, "nr_tags=%u, reserved_tags=%u, " |
693 | "bits_per_word=%u\n", | |
694 | tags->nr_tags, tags->nr_reserved_tags, | |
695 | tags->bitmap_tags.bits_per_word); | |
320ae51f | 696 | |
4bb659b1 JA |
697 | free = bt_unused_tags(&tags->bitmap_tags); |
698 | res = bt_unused_tags(&tags->breserved_tags); | |
320ae51f | 699 | |
4bb659b1 | 700 | page += sprintf(page, "nr_free=%u, nr_reserved=%u\n", free, res); |
0d2602ca | 701 | page += sprintf(page, "active_queues=%u\n", atomic_read(&tags->active_queues)); |
320ae51f JA |
702 | |
703 | return page - orig_page; | |
704 | } |