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 | /* | |
e3a2b3f9 | 71 | * Wakeup all potentially sleeping on normal (non-reserved) tags |
0d2602ca | 72 | */ |
e3a2b3f9 | 73 | static void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags) |
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 JA |
87 | } |
88 | } | |
89 | ||
e3a2b3f9 JA |
90 | /* |
91 | * If a previously busy queue goes inactive, potential waiters could now | |
92 | * be allowed to queue. Wake them up and check. | |
93 | */ | |
94 | void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx) | |
95 | { | |
96 | struct blk_mq_tags *tags = hctx->tags; | |
97 | ||
98 | if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
99 | return; | |
100 | ||
101 | atomic_dec(&tags->active_queues); | |
102 | ||
103 | blk_mq_tag_wakeup_all(tags); | |
104 | } | |
105 | ||
0d2602ca JA |
106 | /* |
107 | * For shared tag users, we track the number of currently active users | |
108 | * and attempt to provide a fair share of the tag depth for each of them. | |
109 | */ | |
110 | static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, | |
111 | struct blk_mq_bitmap_tags *bt) | |
112 | { | |
113 | unsigned int depth, users; | |
114 | ||
115 | if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_SHARED)) | |
116 | return true; | |
117 | if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
118 | return true; | |
119 | ||
120 | /* | |
121 | * Don't try dividing an ant | |
122 | */ | |
123 | if (bt->depth == 1) | |
124 | return true; | |
125 | ||
126 | users = atomic_read(&hctx->tags->active_queues); | |
127 | if (!users) | |
128 | return true; | |
129 | ||
130 | /* | |
131 | * Allow at least some tags | |
132 | */ | |
133 | depth = max((bt->depth + users - 1) / users, 4U); | |
134 | return atomic_read(&hctx->nr_active) < depth; | |
135 | } | |
136 | ||
e93ecf60 | 137 | static int __bt_get_word(struct blk_align_bitmap *bm, unsigned int last_tag) |
4bb659b1 JA |
138 | { |
139 | int tag, org_last_tag, end; | |
9e98e9d7 | 140 | bool wrap = last_tag != 0; |
4bb659b1 | 141 | |
59d13bf5 | 142 | org_last_tag = last_tag; |
4bb659b1 JA |
143 | end = bm->depth; |
144 | do { | |
145 | restart: | |
146 | tag = find_next_zero_bit(&bm->word, end, last_tag); | |
147 | if (unlikely(tag >= end)) { | |
148 | /* | |
149 | * We started with an offset, start from 0 to | |
150 | * exhaust the map. | |
151 | */ | |
9e98e9d7 BVA |
152 | if (wrap) { |
153 | wrap = false; | |
154 | end = org_last_tag; | |
4bb659b1 JA |
155 | last_tag = 0; |
156 | goto restart; | |
157 | } | |
158 | return -1; | |
159 | } | |
160 | last_tag = tag + 1; | |
c38d185d | 161 | } while (test_and_set_bit(tag, &bm->word)); |
4bb659b1 JA |
162 | |
163 | return tag; | |
164 | } | |
165 | ||
166 | /* | |
167 | * Straight forward bitmap tag implementation, where each bit is a tag | |
168 | * (cleared == free, and set == busy). The small twist is using per-cpu | |
169 | * last_tag caches, which blk-mq stores in the blk_mq_ctx software queue | |
170 | * contexts. This enables us to drastically limit the space searched, | |
171 | * without dirtying an extra shared cacheline like we would if we stored | |
172 | * the cache value inside the shared blk_mq_bitmap_tags structure. On top | |
173 | * of that, each word of tags is in a separate cacheline. This means that | |
174 | * multiple users will tend to stick to different cachelines, at least | |
175 | * until the map is exhausted. | |
176 | */ | |
0d2602ca JA |
177 | static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt, |
178 | unsigned int *tag_cache) | |
4bb659b1 JA |
179 | { |
180 | unsigned int last_tag, org_last_tag; | |
181 | int index, i, tag; | |
182 | ||
0d2602ca JA |
183 | if (!hctx_may_queue(hctx, bt)) |
184 | return -1; | |
185 | ||
4bb659b1 | 186 | last_tag = org_last_tag = *tag_cache; |
59d13bf5 | 187 | index = TAG_TO_INDEX(bt, last_tag); |
4bb659b1 JA |
188 | |
189 | for (i = 0; i < bt->map_nr; i++) { | |
59d13bf5 | 190 | tag = __bt_get_word(&bt->map[index], TAG_TO_BIT(bt, last_tag)); |
4bb659b1 | 191 | if (tag != -1) { |
59d13bf5 | 192 | tag += (index << bt->bits_per_word); |
4bb659b1 JA |
193 | goto done; |
194 | } | |
195 | ||
196 | last_tag = 0; | |
197 | if (++index >= bt->map_nr) | |
198 | index = 0; | |
199 | } | |
200 | ||
201 | *tag_cache = 0; | |
202 | return -1; | |
203 | ||
204 | /* | |
205 | * Only update the cache from the allocation path, if we ended | |
206 | * up using the specific cached tag. | |
207 | */ | |
208 | done: | |
209 | if (tag == org_last_tag) { | |
210 | last_tag = tag + 1; | |
211 | if (last_tag >= bt->depth - 1) | |
212 | last_tag = 0; | |
213 | ||
214 | *tag_cache = last_tag; | |
215 | } | |
216 | ||
217 | return tag; | |
218 | } | |
219 | ||
4bb659b1 JA |
220 | static struct bt_wait_state *bt_wait_ptr(struct blk_mq_bitmap_tags *bt, |
221 | struct blk_mq_hw_ctx *hctx) | |
222 | { | |
223 | struct bt_wait_state *bs; | |
8537b120 | 224 | int wait_index; |
4bb659b1 JA |
225 | |
226 | if (!hctx) | |
227 | return &bt->bs[0]; | |
228 | ||
8537b120 AG |
229 | wait_index = atomic_read(&hctx->wait_index); |
230 | bs = &bt->bs[wait_index]; | |
231 | bt_index_atomic_inc(&hctx->wait_index); | |
4bb659b1 | 232 | return bs; |
320ae51f JA |
233 | } |
234 | ||
cb96a42c ML |
235 | static int bt_get(struct blk_mq_alloc_data *data, |
236 | struct blk_mq_bitmap_tags *bt, | |
237 | struct blk_mq_hw_ctx *hctx, | |
238 | unsigned int *last_tag) | |
320ae51f | 239 | { |
4bb659b1 JA |
240 | struct bt_wait_state *bs; |
241 | DEFINE_WAIT(wait); | |
320ae51f JA |
242 | int tag; |
243 | ||
0d2602ca | 244 | tag = __bt_get(hctx, bt, last_tag); |
4bb659b1 JA |
245 | if (tag != -1) |
246 | return tag; | |
247 | ||
cb96a42c | 248 | if (!(data->gfp & __GFP_WAIT)) |
4bb659b1 JA |
249 | return -1; |
250 | ||
35d37c66 | 251 | bs = bt_wait_ptr(bt, hctx); |
4bb659b1 | 252 | do { |
4bb659b1 JA |
253 | prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE); |
254 | ||
0d2602ca | 255 | tag = __bt_get(hctx, bt, last_tag); |
4bb659b1 JA |
256 | if (tag != -1) |
257 | break; | |
258 | ||
b3223207 BVA |
259 | /* |
260 | * We're out of tags on this hardware queue, kick any | |
261 | * pending IO submits before going to sleep waiting for | |
262 | * some to complete. | |
263 | */ | |
264 | blk_mq_run_hw_queue(hctx, false); | |
265 | ||
080ff351 JA |
266 | /* |
267 | * Retry tag allocation after running the hardware queue, | |
268 | * as running the queue may also have found completions. | |
269 | */ | |
270 | tag = __bt_get(hctx, bt, last_tag); | |
271 | if (tag != -1) | |
272 | break; | |
273 | ||
cb96a42c ML |
274 | blk_mq_put_ctx(data->ctx); |
275 | ||
4bb659b1 | 276 | io_schedule(); |
cb96a42c ML |
277 | |
278 | data->ctx = blk_mq_get_ctx(data->q); | |
279 | data->hctx = data->q->mq_ops->map_queue(data->q, | |
280 | data->ctx->cpu); | |
281 | if (data->reserved) { | |
282 | bt = &data->hctx->tags->breserved_tags; | |
283 | } else { | |
284 | last_tag = &data->ctx->last_tag; | |
285 | hctx = data->hctx; | |
286 | bt = &hctx->tags->bitmap_tags; | |
287 | } | |
35d37c66 JA |
288 | finish_wait(&bs->wait, &wait); |
289 | bs = bt_wait_ptr(bt, hctx); | |
4bb659b1 JA |
290 | } while (1); |
291 | ||
292 | finish_wait(&bs->wait, &wait); | |
293 | return tag; | |
294 | } | |
295 | ||
cb96a42c | 296 | static unsigned int __blk_mq_get_tag(struct blk_mq_alloc_data *data) |
4bb659b1 JA |
297 | { |
298 | int tag; | |
299 | ||
cb96a42c ML |
300 | tag = bt_get(data, &data->hctx->tags->bitmap_tags, data->hctx, |
301 | &data->ctx->last_tag); | |
4bb659b1 | 302 | if (tag >= 0) |
cb96a42c | 303 | return tag + data->hctx->tags->nr_reserved_tags; |
4bb659b1 JA |
304 | |
305 | return BLK_MQ_TAG_FAIL; | |
320ae51f JA |
306 | } |
307 | ||
cb96a42c | 308 | static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_alloc_data *data) |
320ae51f | 309 | { |
4bb659b1 | 310 | int tag, zero = 0; |
320ae51f | 311 | |
cb96a42c | 312 | if (unlikely(!data->hctx->tags->nr_reserved_tags)) { |
320ae51f JA |
313 | WARN_ON_ONCE(1); |
314 | return BLK_MQ_TAG_FAIL; | |
315 | } | |
316 | ||
cb96a42c | 317 | tag = bt_get(data, &data->hctx->tags->breserved_tags, NULL, &zero); |
320ae51f JA |
318 | if (tag < 0) |
319 | return BLK_MQ_TAG_FAIL; | |
4bb659b1 | 320 | |
320ae51f JA |
321 | return tag; |
322 | } | |
323 | ||
cb96a42c | 324 | unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) |
320ae51f | 325 | { |
cb96a42c ML |
326 | if (!data->reserved) |
327 | return __blk_mq_get_tag(data); | |
320ae51f | 328 | |
cb96a42c | 329 | return __blk_mq_get_reserved_tag(data); |
320ae51f JA |
330 | } |
331 | ||
4bb659b1 JA |
332 | static struct bt_wait_state *bt_wake_ptr(struct blk_mq_bitmap_tags *bt) |
333 | { | |
334 | int i, wake_index; | |
335 | ||
8537b120 | 336 | wake_index = atomic_read(&bt->wake_index); |
4bb659b1 JA |
337 | for (i = 0; i < BT_WAIT_QUEUES; i++) { |
338 | struct bt_wait_state *bs = &bt->bs[wake_index]; | |
339 | ||
340 | if (waitqueue_active(&bs->wait)) { | |
8537b120 AG |
341 | int o = atomic_read(&bt->wake_index); |
342 | if (wake_index != o) | |
343 | atomic_cmpxchg(&bt->wake_index, o, wake_index); | |
4bb659b1 JA |
344 | |
345 | return bs; | |
346 | } | |
347 | ||
8537b120 | 348 | wake_index = bt_index_inc(wake_index); |
4bb659b1 JA |
349 | } |
350 | ||
351 | return NULL; | |
352 | } | |
353 | ||
354 | static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag) | |
355 | { | |
59d13bf5 | 356 | const int index = TAG_TO_INDEX(bt, tag); |
4bb659b1 | 357 | struct bt_wait_state *bs; |
2971c35f | 358 | int wait_cnt; |
4bb659b1 | 359 | |
c38d185d BVA |
360 | clear_bit(TAG_TO_BIT(bt, tag), &bt->map[index].word); |
361 | ||
362 | /* Ensure that the wait list checks occur after clear_bit(). */ | |
363 | smp_mb(); | |
4bb659b1 JA |
364 | |
365 | bs = bt_wake_ptr(bt); | |
2971c35f AG |
366 | if (!bs) |
367 | return; | |
368 | ||
369 | wait_cnt = atomic_dec_return(&bs->wait_cnt); | |
9d8f0bcc BVA |
370 | if (unlikely(wait_cnt < 0)) |
371 | wait_cnt = atomic_inc_return(&bs->wait_cnt); | |
2971c35f | 372 | if (wait_cnt == 0) { |
2971c35f | 373 | atomic_add(bt->wake_cnt, &bs->wait_cnt); |
8537b120 | 374 | bt_index_atomic_inc(&bt->wake_index); |
4bb659b1 JA |
375 | wake_up(&bs->wait); |
376 | } | |
377 | } | |
378 | ||
0d2602ca | 379 | void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, unsigned int tag, |
4bb659b1 | 380 | unsigned int *last_tag) |
320ae51f | 381 | { |
0d2602ca JA |
382 | struct blk_mq_tags *tags = hctx->tags; |
383 | ||
4bb659b1 JA |
384 | if (tag >= tags->nr_reserved_tags) { |
385 | const int real_tag = tag - tags->nr_reserved_tags; | |
386 | ||
70114c39 JA |
387 | BUG_ON(real_tag >= tags->nr_tags); |
388 | bt_clear_tag(&tags->bitmap_tags, real_tag); | |
4bb659b1 | 389 | *last_tag = real_tag; |
70114c39 JA |
390 | } else { |
391 | BUG_ON(tag >= tags->nr_reserved_tags); | |
392 | bt_clear_tag(&tags->breserved_tags, tag); | |
393 | } | |
320ae51f JA |
394 | } |
395 | ||
81481eb4 CH |
396 | static void bt_for_each(struct blk_mq_hw_ctx *hctx, |
397 | struct blk_mq_bitmap_tags *bt, unsigned int off, | |
398 | busy_iter_fn *fn, void *data, bool reserved) | |
320ae51f | 399 | { |
81481eb4 CH |
400 | struct request *rq; |
401 | int bit, i; | |
4bb659b1 JA |
402 | |
403 | for (i = 0; i < bt->map_nr; i++) { | |
e93ecf60 | 404 | struct blk_align_bitmap *bm = &bt->map[i]; |
4bb659b1 | 405 | |
81481eb4 CH |
406 | for (bit = find_first_bit(&bm->word, bm->depth); |
407 | bit < bm->depth; | |
408 | bit = find_next_bit(&bm->word, bm->depth, bit + 1)) { | |
409 | rq = blk_mq_tag_to_rq(hctx->tags, off + bit); | |
410 | if (rq->q == hctx->queue) | |
411 | fn(hctx, rq, data, reserved); | |
412 | } | |
4bb659b1 | 413 | |
59d13bf5 | 414 | off += (1 << bt->bits_per_word); |
4bb659b1 | 415 | } |
320ae51f JA |
416 | } |
417 | ||
81481eb4 CH |
418 | void blk_mq_tag_busy_iter(struct blk_mq_hw_ctx *hctx, busy_iter_fn *fn, |
419 | void *priv) | |
320ae51f | 420 | { |
81481eb4 | 421 | struct blk_mq_tags *tags = hctx->tags; |
320ae51f | 422 | |
320ae51f | 423 | if (tags->nr_reserved_tags) |
81481eb4 CH |
424 | bt_for_each(hctx, &tags->breserved_tags, 0, fn, priv, true); |
425 | bt_for_each(hctx, &tags->bitmap_tags, tags->nr_reserved_tags, fn, priv, | |
426 | false); | |
320ae51f | 427 | } |
edf866b3 | 428 | EXPORT_SYMBOL(blk_mq_tag_busy_iter); |
320ae51f | 429 | |
4bb659b1 JA |
430 | static unsigned int bt_unused_tags(struct blk_mq_bitmap_tags *bt) |
431 | { | |
432 | unsigned int i, used; | |
433 | ||
434 | for (i = 0, used = 0; i < bt->map_nr; i++) { | |
e93ecf60 | 435 | struct blk_align_bitmap *bm = &bt->map[i]; |
4bb659b1 JA |
436 | |
437 | used += bitmap_weight(&bm->word, bm->depth); | |
438 | } | |
439 | ||
440 | return bt->depth - used; | |
441 | } | |
442 | ||
e3a2b3f9 JA |
443 | static void bt_update_count(struct blk_mq_bitmap_tags *bt, |
444 | unsigned int depth) | |
445 | { | |
446 | unsigned int tags_per_word = 1U << bt->bits_per_word; | |
447 | unsigned int map_depth = depth; | |
448 | ||
449 | if (depth) { | |
450 | int i; | |
451 | ||
452 | for (i = 0; i < bt->map_nr; i++) { | |
453 | bt->map[i].depth = min(map_depth, tags_per_word); | |
454 | map_depth -= bt->map[i].depth; | |
455 | } | |
456 | } | |
457 | ||
458 | bt->wake_cnt = BT_WAIT_BATCH; | |
abab13b5 JA |
459 | if (bt->wake_cnt > depth / BT_WAIT_QUEUES) |
460 | bt->wake_cnt = max(1U, depth / BT_WAIT_QUEUES); | |
e3a2b3f9 JA |
461 | |
462 | bt->depth = depth; | |
463 | } | |
464 | ||
4bb659b1 JA |
465 | static int bt_alloc(struct blk_mq_bitmap_tags *bt, unsigned int depth, |
466 | int node, bool reserved) | |
467 | { | |
468 | int i; | |
469 | ||
59d13bf5 JA |
470 | bt->bits_per_word = ilog2(BITS_PER_LONG); |
471 | ||
4bb659b1 JA |
472 | /* |
473 | * Depth can be zero for reserved tags, that's not a failure | |
474 | * condition. | |
475 | */ | |
476 | if (depth) { | |
e3a2b3f9 | 477 | unsigned int nr, tags_per_word; |
59d13bf5 JA |
478 | |
479 | tags_per_word = (1 << bt->bits_per_word); | |
480 | ||
481 | /* | |
482 | * If the tag space is small, shrink the number of tags | |
483 | * per word so we spread over a few cachelines, at least. | |
484 | * If less than 4 tags, just forget about it, it's not | |
485 | * going to work optimally anyway. | |
486 | */ | |
487 | if (depth >= 4) { | |
488 | while (tags_per_word * 4 > depth) { | |
489 | bt->bits_per_word--; | |
490 | tags_per_word = (1 << bt->bits_per_word); | |
491 | } | |
492 | } | |
4bb659b1 | 493 | |
59d13bf5 | 494 | nr = ALIGN(depth, tags_per_word) / tags_per_word; |
e93ecf60 | 495 | bt->map = kzalloc_node(nr * sizeof(struct blk_align_bitmap), |
4bb659b1 JA |
496 | GFP_KERNEL, node); |
497 | if (!bt->map) | |
498 | return -ENOMEM; | |
499 | ||
500 | bt->map_nr = nr; | |
4bb659b1 JA |
501 | } |
502 | ||
503 | bt->bs = kzalloc(BT_WAIT_QUEUES * sizeof(*bt->bs), GFP_KERNEL); | |
504 | if (!bt->bs) { | |
505 | kfree(bt->map); | |
506 | return -ENOMEM; | |
507 | } | |
508 | ||
86fb5c56 AG |
509 | bt_update_count(bt, depth); |
510 | ||
511 | for (i = 0; i < BT_WAIT_QUEUES; i++) { | |
4bb659b1 | 512 | init_waitqueue_head(&bt->bs[i].wait); |
86fb5c56 AG |
513 | atomic_set(&bt->bs[i].wait_cnt, bt->wake_cnt); |
514 | } | |
4bb659b1 | 515 | |
4bb659b1 JA |
516 | return 0; |
517 | } | |
518 | ||
519 | static void bt_free(struct blk_mq_bitmap_tags *bt) | |
520 | { | |
521 | kfree(bt->map); | |
522 | kfree(bt->bs); | |
523 | } | |
524 | ||
525 | static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, | |
526 | int node) | |
527 | { | |
528 | unsigned int depth = tags->nr_tags - tags->nr_reserved_tags; | |
529 | ||
530 | if (bt_alloc(&tags->bitmap_tags, depth, node, false)) | |
531 | goto enomem; | |
532 | if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, node, true)) | |
533 | goto enomem; | |
534 | ||
535 | return tags; | |
536 | enomem: | |
537 | bt_free(&tags->bitmap_tags); | |
538 | kfree(tags); | |
539 | return NULL; | |
540 | } | |
541 | ||
320ae51f JA |
542 | struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, |
543 | unsigned int reserved_tags, int node) | |
544 | { | |
320ae51f | 545 | struct blk_mq_tags *tags; |
320ae51f JA |
546 | |
547 | if (total_tags > BLK_MQ_TAG_MAX) { | |
548 | pr_err("blk-mq: tag depth too large\n"); | |
549 | return NULL; | |
550 | } | |
551 | ||
552 | tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node); | |
553 | if (!tags) | |
554 | return NULL; | |
555 | ||
320ae51f JA |
556 | tags->nr_tags = total_tags; |
557 | tags->nr_reserved_tags = reserved_tags; | |
320ae51f | 558 | |
4bb659b1 | 559 | return blk_mq_init_bitmap_tags(tags, node); |
320ae51f JA |
560 | } |
561 | ||
562 | void blk_mq_free_tags(struct blk_mq_tags *tags) | |
563 | { | |
4bb659b1 JA |
564 | bt_free(&tags->bitmap_tags); |
565 | bt_free(&tags->breserved_tags); | |
320ae51f JA |
566 | kfree(tags); |
567 | } | |
568 | ||
4bb659b1 JA |
569 | void blk_mq_tag_init_last_tag(struct blk_mq_tags *tags, unsigned int *tag) |
570 | { | |
571 | unsigned int depth = tags->nr_tags - tags->nr_reserved_tags; | |
572 | ||
9d3d21ae | 573 | *tag = prandom_u32() % depth; |
4bb659b1 JA |
574 | } |
575 | ||
e3a2b3f9 JA |
576 | int blk_mq_tag_update_depth(struct blk_mq_tags *tags, unsigned int tdepth) |
577 | { | |
578 | tdepth -= tags->nr_reserved_tags; | |
579 | if (tdepth > tags->nr_tags) | |
580 | return -EINVAL; | |
581 | ||
582 | /* | |
583 | * Don't need (or can't) update reserved tags here, they remain | |
584 | * static and should never need resizing. | |
585 | */ | |
586 | bt_update_count(&tags->bitmap_tags, tdepth); | |
587 | blk_mq_tag_wakeup_all(tags); | |
588 | return 0; | |
589 | } | |
590 | ||
205fb5f5 BVA |
591 | /** |
592 | * blk_mq_unique_tag() - return a tag that is unique queue-wide | |
593 | * @rq: request for which to compute a unique tag | |
594 | * | |
595 | * The tag field in struct request is unique per hardware queue but not over | |
596 | * all hardware queues. Hence this function that returns a tag with the | |
597 | * hardware context index in the upper bits and the per hardware queue tag in | |
598 | * the lower bits. | |
599 | * | |
600 | * Note: When called for a request that is queued on a non-multiqueue request | |
601 | * queue, the hardware context index is set to zero. | |
602 | */ | |
603 | u32 blk_mq_unique_tag(struct request *rq) | |
604 | { | |
605 | struct request_queue *q = rq->q; | |
606 | struct blk_mq_hw_ctx *hctx; | |
607 | int hwq = 0; | |
608 | ||
609 | if (q->mq_ops) { | |
610 | hctx = q->mq_ops->map_queue(q, rq->mq_ctx->cpu); | |
611 | hwq = hctx->queue_num; | |
612 | } | |
613 | ||
614 | return (hwq << BLK_MQ_UNIQUE_TAG_BITS) | | |
615 | (rq->tag & BLK_MQ_UNIQUE_TAG_MASK); | |
616 | } | |
617 | EXPORT_SYMBOL(blk_mq_unique_tag); | |
618 | ||
320ae51f JA |
619 | ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page) |
620 | { | |
621 | char *orig_page = page; | |
4bb659b1 | 622 | unsigned int free, res; |
320ae51f JA |
623 | |
624 | if (!tags) | |
625 | return 0; | |
626 | ||
59d13bf5 JA |
627 | page += sprintf(page, "nr_tags=%u, reserved_tags=%u, " |
628 | "bits_per_word=%u\n", | |
629 | tags->nr_tags, tags->nr_reserved_tags, | |
630 | tags->bitmap_tags.bits_per_word); | |
320ae51f | 631 | |
4bb659b1 JA |
632 | free = bt_unused_tags(&tags->bitmap_tags); |
633 | res = bt_unused_tags(&tags->breserved_tags); | |
320ae51f | 634 | |
4bb659b1 | 635 | page += sprintf(page, "nr_free=%u, nr_reserved=%u\n", free, res); |
0d2602ca | 636 | page += sprintf(page, "active_queues=%u\n", atomic_read(&tags->active_queues)); |
320ae51f JA |
637 | |
638 | return page - orig_page; | |
639 | } |