Commit | Line | Data |
---|---|---|
75bb4625 | 1 | /* |
88459642 OS |
2 | * Tag allocation using scalable bitmaps. Uses active queue tracking to support |
3 | * fairer distribution of tags between multiple submitters when a shared tag map | |
4 | * is used. | |
75bb4625 JA |
5 | * |
6 | * Copyright (C) 2013-2014 Jens Axboe | |
7 | */ | |
320ae51f JA |
8 | #include <linux/kernel.h> |
9 | #include <linux/module.h> | |
320ae51f JA |
10 | |
11 | #include <linux/blk-mq.h> | |
12 | #include "blk.h" | |
13 | #include "blk-mq.h" | |
14 | #include "blk-mq-tag.h" | |
15 | ||
320ae51f JA |
16 | bool blk_mq_has_free_tags(struct blk_mq_tags *tags) |
17 | { | |
4bb659b1 JA |
18 | if (!tags) |
19 | return true; | |
20 | ||
88459642 | 21 | return sbitmap_any_bit_clear(&tags->bitmap_tags.sb); |
0d2602ca JA |
22 | } |
23 | ||
24 | /* | |
25 | * If a previously inactive queue goes active, bump the active user count. | |
26 | */ | |
27 | bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx) | |
28 | { | |
29 | if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) && | |
30 | !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
31 | atomic_inc(&hctx->tags->active_queues); | |
32 | ||
33 | return true; | |
34 | } | |
35 | ||
36 | /* | |
aed3ea94 | 37 | * Wakeup all potentially sleeping on tags |
0d2602ca | 38 | */ |
aed3ea94 | 39 | void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool include_reserve) |
0d2602ca | 40 | { |
88459642 OS |
41 | sbitmap_queue_wake_all(&tags->bitmap_tags); |
42 | if (include_reserve) | |
43 | sbitmap_queue_wake_all(&tags->breserved_tags); | |
0d2602ca JA |
44 | } |
45 | ||
e3a2b3f9 JA |
46 | /* |
47 | * If a previously busy queue goes inactive, potential waiters could now | |
48 | * be allowed to queue. Wake them up and check. | |
49 | */ | |
50 | void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx) | |
51 | { | |
52 | struct blk_mq_tags *tags = hctx->tags; | |
53 | ||
54 | if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
55 | return; | |
56 | ||
57 | atomic_dec(&tags->active_queues); | |
58 | ||
aed3ea94 | 59 | blk_mq_tag_wakeup_all(tags, false); |
e3a2b3f9 JA |
60 | } |
61 | ||
0d2602ca JA |
62 | /* |
63 | * For shared tag users, we track the number of currently active users | |
64 | * and attempt to provide a fair share of the tag depth for each of them. | |
65 | */ | |
66 | static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, | |
88459642 | 67 | struct sbitmap_queue *bt) |
0d2602ca JA |
68 | { |
69 | unsigned int depth, users; | |
70 | ||
71 | if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_SHARED)) | |
72 | return true; | |
73 | if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
74 | return true; | |
75 | ||
76 | /* | |
77 | * Don't try dividing an ant | |
78 | */ | |
88459642 | 79 | if (bt->sb.depth == 1) |
0d2602ca JA |
80 | return true; |
81 | ||
82 | users = atomic_read(&hctx->tags->active_queues); | |
83 | if (!users) | |
84 | return true; | |
85 | ||
86 | /* | |
87 | * Allow at least some tags | |
88 | */ | |
88459642 | 89 | depth = max((bt->sb.depth + users - 1) / users, 4U); |
0d2602ca JA |
90 | return atomic_read(&hctx->nr_active) < depth; |
91 | } | |
92 | ||
4941115b | 93 | static int __blk_mq_get_tag(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt) |
4bb659b1 | 94 | { |
0d2602ca JA |
95 | if (!hctx_may_queue(hctx, bt)) |
96 | return -1; | |
f4a644db | 97 | return __sbitmap_queue_get(bt); |
4bb659b1 JA |
98 | } |
99 | ||
4941115b | 100 | unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) |
320ae51f | 101 | { |
4941115b JA |
102 | struct blk_mq_tags *tags = blk_mq_tags_from_data(data); |
103 | struct sbitmap_queue *bt; | |
88459642 | 104 | struct sbq_wait_state *ws; |
4bb659b1 | 105 | DEFINE_WAIT(wait); |
4941115b | 106 | unsigned int tag_offset; |
320ae51f JA |
107 | int tag; |
108 | ||
4941115b JA |
109 | if (data->flags & BLK_MQ_REQ_RESERVED) { |
110 | if (unlikely(!tags->nr_reserved_tags)) { | |
111 | WARN_ON_ONCE(1); | |
112 | return BLK_MQ_TAG_FAIL; | |
113 | } | |
114 | bt = &tags->breserved_tags; | |
115 | tag_offset = 0; | |
116 | } else { | |
117 | bt = &tags->bitmap_tags; | |
118 | tag_offset = tags->nr_reserved_tags; | |
119 | } | |
120 | ||
121 | tag = __blk_mq_get_tag(data->hctx, bt); | |
4bb659b1 | 122 | if (tag != -1) |
4941115b | 123 | goto found_tag; |
4bb659b1 | 124 | |
6f3b0e8b | 125 | if (data->flags & BLK_MQ_REQ_NOWAIT) |
4941115b | 126 | return BLK_MQ_TAG_FAIL; |
4bb659b1 | 127 | |
4941115b | 128 | ws = bt_wait_ptr(bt, data->hctx); |
4bb659b1 | 129 | do { |
88459642 | 130 | prepare_to_wait(&ws->wait, &wait, TASK_UNINTERRUPTIBLE); |
4bb659b1 | 131 | |
4941115b | 132 | tag = __blk_mq_get_tag(data->hctx, bt); |
4bb659b1 JA |
133 | if (tag != -1) |
134 | break; | |
135 | ||
b3223207 BVA |
136 | /* |
137 | * We're out of tags on this hardware queue, kick any | |
138 | * pending IO submits before going to sleep waiting for | |
8cecb07d | 139 | * some to complete. |
b3223207 | 140 | */ |
8cecb07d | 141 | blk_mq_run_hw_queue(data->hctx, false); |
b3223207 | 142 | |
080ff351 JA |
143 | /* |
144 | * Retry tag allocation after running the hardware queue, | |
145 | * as running the queue may also have found completions. | |
146 | */ | |
4941115b | 147 | tag = __blk_mq_get_tag(data->hctx, bt); |
080ff351 JA |
148 | if (tag != -1) |
149 | break; | |
150 | ||
cb96a42c ML |
151 | blk_mq_put_ctx(data->ctx); |
152 | ||
4bb659b1 | 153 | io_schedule(); |
cb96a42c ML |
154 | |
155 | data->ctx = blk_mq_get_ctx(data->q); | |
7d7e0f90 | 156 | data->hctx = blk_mq_map_queue(data->q, data->ctx->cpu); |
4941115b JA |
157 | tags = blk_mq_tags_from_data(data); |
158 | if (data->flags & BLK_MQ_REQ_RESERVED) | |
159 | bt = &tags->breserved_tags; | |
160 | else | |
161 | bt = &tags->bitmap_tags; | |
162 | ||
88459642 | 163 | finish_wait(&ws->wait, &wait); |
4941115b | 164 | ws = bt_wait_ptr(bt, data->hctx); |
4bb659b1 JA |
165 | } while (1); |
166 | ||
88459642 | 167 | finish_wait(&ws->wait, &wait); |
320ae51f | 168 | |
4941115b JA |
169 | found_tag: |
170 | return tag + tag_offset; | |
320ae51f JA |
171 | } |
172 | ||
4941115b JA |
173 | void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_tags *tags, |
174 | struct blk_mq_ctx *ctx, unsigned int tag) | |
320ae51f | 175 | { |
4bb659b1 JA |
176 | if (tag >= tags->nr_reserved_tags) { |
177 | const int real_tag = tag - tags->nr_reserved_tags; | |
178 | ||
70114c39 | 179 | BUG_ON(real_tag >= tags->nr_tags); |
f4a644db | 180 | sbitmap_queue_clear(&tags->bitmap_tags, real_tag, ctx->cpu); |
70114c39 JA |
181 | } else { |
182 | BUG_ON(tag >= tags->nr_reserved_tags); | |
f4a644db | 183 | sbitmap_queue_clear(&tags->breserved_tags, tag, ctx->cpu); |
70114c39 | 184 | } |
320ae51f JA |
185 | } |
186 | ||
88459642 OS |
187 | struct bt_iter_data { |
188 | struct blk_mq_hw_ctx *hctx; | |
189 | busy_iter_fn *fn; | |
190 | void *data; | |
191 | bool reserved; | |
192 | }; | |
193 | ||
194 | static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) | |
320ae51f | 195 | { |
88459642 OS |
196 | struct bt_iter_data *iter_data = data; |
197 | struct blk_mq_hw_ctx *hctx = iter_data->hctx; | |
198 | struct blk_mq_tags *tags = hctx->tags; | |
199 | bool reserved = iter_data->reserved; | |
81481eb4 | 200 | struct request *rq; |
4bb659b1 | 201 | |
88459642 OS |
202 | if (!reserved) |
203 | bitnr += tags->nr_reserved_tags; | |
204 | rq = tags->rqs[bitnr]; | |
4bb659b1 | 205 | |
88459642 OS |
206 | if (rq->q == hctx->queue) |
207 | iter_data->fn(hctx, rq, iter_data->data, reserved); | |
208 | return true; | |
209 | } | |
4bb659b1 | 210 | |
88459642 OS |
211 | static void bt_for_each(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt, |
212 | busy_iter_fn *fn, void *data, bool reserved) | |
213 | { | |
214 | struct bt_iter_data iter_data = { | |
215 | .hctx = hctx, | |
216 | .fn = fn, | |
217 | .data = data, | |
218 | .reserved = reserved, | |
219 | }; | |
220 | ||
221 | sbitmap_for_each_set(&bt->sb, bt_iter, &iter_data); | |
320ae51f JA |
222 | } |
223 | ||
88459642 OS |
224 | struct bt_tags_iter_data { |
225 | struct blk_mq_tags *tags; | |
226 | busy_tag_iter_fn *fn; | |
227 | void *data; | |
228 | bool reserved; | |
229 | }; | |
230 | ||
231 | static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) | |
f26cdc85 | 232 | { |
88459642 OS |
233 | struct bt_tags_iter_data *iter_data = data; |
234 | struct blk_mq_tags *tags = iter_data->tags; | |
235 | bool reserved = iter_data->reserved; | |
f26cdc85 | 236 | struct request *rq; |
f26cdc85 | 237 | |
88459642 OS |
238 | if (!reserved) |
239 | bitnr += tags->nr_reserved_tags; | |
240 | rq = tags->rqs[bitnr]; | |
f26cdc85 | 241 | |
88459642 OS |
242 | iter_data->fn(rq, iter_data->data, reserved); |
243 | return true; | |
244 | } | |
245 | ||
246 | static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt, | |
247 | busy_tag_iter_fn *fn, void *data, bool reserved) | |
248 | { | |
249 | struct bt_tags_iter_data iter_data = { | |
250 | .tags = tags, | |
251 | .fn = fn, | |
252 | .data = data, | |
253 | .reserved = reserved, | |
254 | }; | |
255 | ||
256 | if (tags->rqs) | |
257 | sbitmap_for_each_set(&bt->sb, bt_tags_iter, &iter_data); | |
f26cdc85 KB |
258 | } |
259 | ||
e8f1e163 SG |
260 | static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, |
261 | busy_tag_iter_fn *fn, void *priv) | |
f26cdc85 KB |
262 | { |
263 | if (tags->nr_reserved_tags) | |
88459642 OS |
264 | bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true); |
265 | bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false); | |
f26cdc85 | 266 | } |
f26cdc85 | 267 | |
e0489487 SG |
268 | void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset, |
269 | busy_tag_iter_fn *fn, void *priv) | |
270 | { | |
271 | int i; | |
272 | ||
273 | for (i = 0; i < tagset->nr_hw_queues; i++) { | |
274 | if (tagset->tags && tagset->tags[i]) | |
275 | blk_mq_all_tag_busy_iter(tagset->tags[i], fn, priv); | |
276 | } | |
277 | } | |
278 | EXPORT_SYMBOL(blk_mq_tagset_busy_iter); | |
279 | ||
486cf989 SG |
280 | int blk_mq_reinit_tagset(struct blk_mq_tag_set *set) |
281 | { | |
282 | int i, j, ret = 0; | |
283 | ||
284 | if (!set->ops->reinit_request) | |
285 | goto out; | |
286 | ||
287 | for (i = 0; i < set->nr_hw_queues; i++) { | |
288 | struct blk_mq_tags *tags = set->tags[i]; | |
289 | ||
290 | for (j = 0; j < tags->nr_tags; j++) { | |
2af8cbe3 | 291 | if (!tags->static_rqs[j]) |
486cf989 SG |
292 | continue; |
293 | ||
294 | ret = set->ops->reinit_request(set->driver_data, | |
2af8cbe3 | 295 | tags->static_rqs[j]); |
486cf989 SG |
296 | if (ret) |
297 | goto out; | |
298 | } | |
299 | } | |
300 | ||
301 | out: | |
302 | return ret; | |
303 | } | |
304 | EXPORT_SYMBOL_GPL(blk_mq_reinit_tagset); | |
305 | ||
0bf6cd5b | 306 | void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, |
81481eb4 | 307 | void *priv) |
320ae51f | 308 | { |
0bf6cd5b CH |
309 | struct blk_mq_hw_ctx *hctx; |
310 | int i; | |
311 | ||
312 | ||
313 | queue_for_each_hw_ctx(q, hctx, i) { | |
314 | struct blk_mq_tags *tags = hctx->tags; | |
315 | ||
316 | /* | |
317 | * If not software queues are currently mapped to this | |
318 | * hardware queue, there's nothing to check | |
319 | */ | |
320 | if (!blk_mq_hw_queue_mapped(hctx)) | |
321 | continue; | |
322 | ||
323 | if (tags->nr_reserved_tags) | |
88459642 OS |
324 | bt_for_each(hctx, &tags->breserved_tags, fn, priv, true); |
325 | bt_for_each(hctx, &tags->bitmap_tags, fn, priv, false); | |
4bb659b1 JA |
326 | } |
327 | ||
4bb659b1 JA |
328 | } |
329 | ||
88459642 | 330 | static unsigned int bt_unused_tags(const struct sbitmap_queue *bt) |
e3a2b3f9 | 331 | { |
88459642 | 332 | return bt->sb.depth - sbitmap_weight(&bt->sb); |
e3a2b3f9 JA |
333 | } |
334 | ||
f4a644db OS |
335 | static int bt_alloc(struct sbitmap_queue *bt, unsigned int depth, |
336 | bool round_robin, int node) | |
4bb659b1 | 337 | { |
f4a644db OS |
338 | return sbitmap_queue_init_node(bt, depth, -1, round_robin, GFP_KERNEL, |
339 | node); | |
4bb659b1 JA |
340 | } |
341 | ||
342 | static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, | |
24391c0d | 343 | int node, int alloc_policy) |
4bb659b1 JA |
344 | { |
345 | unsigned int depth = tags->nr_tags - tags->nr_reserved_tags; | |
f4a644db | 346 | bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR; |
4bb659b1 | 347 | |
f4a644db | 348 | if (bt_alloc(&tags->bitmap_tags, depth, round_robin, node)) |
88459642 | 349 | goto free_tags; |
f4a644db OS |
350 | if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, round_robin, |
351 | node)) | |
88459642 | 352 | goto free_bitmap_tags; |
4bb659b1 JA |
353 | |
354 | return tags; | |
88459642 OS |
355 | free_bitmap_tags: |
356 | sbitmap_queue_free(&tags->bitmap_tags); | |
357 | free_tags: | |
4bb659b1 JA |
358 | kfree(tags); |
359 | return NULL; | |
360 | } | |
361 | ||
320ae51f | 362 | struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, |
24391c0d SL |
363 | unsigned int reserved_tags, |
364 | int node, int alloc_policy) | |
320ae51f | 365 | { |
320ae51f | 366 | struct blk_mq_tags *tags; |
320ae51f JA |
367 | |
368 | if (total_tags > BLK_MQ_TAG_MAX) { | |
369 | pr_err("blk-mq: tag depth too large\n"); | |
370 | return NULL; | |
371 | } | |
372 | ||
373 | tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node); | |
374 | if (!tags) | |
375 | return NULL; | |
376 | ||
320ae51f JA |
377 | tags->nr_tags = total_tags; |
378 | tags->nr_reserved_tags = reserved_tags; | |
320ae51f | 379 | |
24391c0d | 380 | return blk_mq_init_bitmap_tags(tags, node, alloc_policy); |
320ae51f JA |
381 | } |
382 | ||
383 | void blk_mq_free_tags(struct blk_mq_tags *tags) | |
384 | { | |
88459642 OS |
385 | sbitmap_queue_free(&tags->bitmap_tags); |
386 | sbitmap_queue_free(&tags->breserved_tags); | |
320ae51f JA |
387 | kfree(tags); |
388 | } | |
389 | ||
e3a2b3f9 JA |
390 | int blk_mq_tag_update_depth(struct blk_mq_tags *tags, unsigned int tdepth) |
391 | { | |
392 | tdepth -= tags->nr_reserved_tags; | |
393 | if (tdepth > tags->nr_tags) | |
394 | return -EINVAL; | |
395 | ||
396 | /* | |
397 | * Don't need (or can't) update reserved tags here, they remain | |
398 | * static and should never need resizing. | |
399 | */ | |
88459642 OS |
400 | sbitmap_queue_resize(&tags->bitmap_tags, tdepth); |
401 | ||
aed3ea94 | 402 | blk_mq_tag_wakeup_all(tags, false); |
e3a2b3f9 JA |
403 | return 0; |
404 | } | |
405 | ||
205fb5f5 BVA |
406 | /** |
407 | * blk_mq_unique_tag() - return a tag that is unique queue-wide | |
408 | * @rq: request for which to compute a unique tag | |
409 | * | |
410 | * The tag field in struct request is unique per hardware queue but not over | |
411 | * all hardware queues. Hence this function that returns a tag with the | |
412 | * hardware context index in the upper bits and the per hardware queue tag in | |
413 | * the lower bits. | |
414 | * | |
415 | * Note: When called for a request that is queued on a non-multiqueue request | |
416 | * queue, the hardware context index is set to zero. | |
417 | */ | |
418 | u32 blk_mq_unique_tag(struct request *rq) | |
419 | { | |
420 | struct request_queue *q = rq->q; | |
421 | struct blk_mq_hw_ctx *hctx; | |
422 | int hwq = 0; | |
423 | ||
424 | if (q->mq_ops) { | |
7d7e0f90 | 425 | hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu); |
205fb5f5 BVA |
426 | hwq = hctx->queue_num; |
427 | } | |
428 | ||
429 | return (hwq << BLK_MQ_UNIQUE_TAG_BITS) | | |
430 | (rq->tag & BLK_MQ_UNIQUE_TAG_MASK); | |
431 | } | |
432 | EXPORT_SYMBOL(blk_mq_unique_tag); | |
433 | ||
320ae51f JA |
434 | ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page) |
435 | { | |
436 | char *orig_page = page; | |
4bb659b1 | 437 | unsigned int free, res; |
320ae51f JA |
438 | |
439 | if (!tags) | |
440 | return 0; | |
441 | ||
59d13bf5 JA |
442 | page += sprintf(page, "nr_tags=%u, reserved_tags=%u, " |
443 | "bits_per_word=%u\n", | |
444 | tags->nr_tags, tags->nr_reserved_tags, | |
88459642 | 445 | 1U << tags->bitmap_tags.sb.shift); |
320ae51f | 446 | |
4bb659b1 JA |
447 | free = bt_unused_tags(&tags->bitmap_tags); |
448 | res = bt_unused_tags(&tags->breserved_tags); | |
320ae51f | 449 | |
4bb659b1 | 450 | page += sprintf(page, "nr_free=%u, nr_reserved=%u\n", free, res); |
0d2602ca | 451 | page += sprintf(page, "active_queues=%u\n", atomic_read(&tags->active_queues)); |
320ae51f JA |
452 | |
453 | return page - orig_page; | |
454 | } |