Jens Axboe | 75bb462 | 2014-05-28 10:15:41 -0600 | [diff] [blame] | 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 | */ |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 13 | #include <linux/kernel.h> |
| 14 | #include <linux/module.h> |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 15 | #include <linux/random.h> |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 16 | |
| 17 | #include <linux/blk-mq.h> |
| 18 | #include "blk.h" |
| 19 | #include "blk-mq.h" |
| 20 | #include "blk-mq-tag.h" |
| 21 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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++) { |
Jens Axboe | e93ecf6 | 2014-05-19 09:17:48 -0600 | [diff] [blame] | 27 | struct blk_align_bitmap *bm = &bt->map[i]; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 36 | } |
| 37 | |
| 38 | bool blk_mq_has_free_tags(struct blk_mq_tags *tags) |
| 39 | { |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 40 | if (!tags) |
| 41 | return true; |
| 42 | |
| 43 | return bt_has_free_tags(&tags->bitmap_tags); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 44 | } |
| 45 | |
Alexander Gordeev | 8537b12 | 2014-06-17 22:12:35 -0700 | [diff] [blame] | 46 | static inline int bt_index_inc(int index) |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 47 | { |
Alexander Gordeev | 8537b12 | 2014-06-17 22:12:35 -0700 | [diff] [blame] | 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); |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 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 | /* |
Jens Axboe | e3a2b3f | 2014-05-20 11:49:02 -0600 | [diff] [blame] | 71 | * Wakeup all potentially sleeping on normal (non-reserved) tags |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 72 | */ |
Jens Axboe | e3a2b3f | 2014-05-20 11:49:02 -0600 | [diff] [blame] | 73 | static void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags) |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 74 | { |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 75 | struct blk_mq_bitmap_tags *bt; |
| 76 | int i, wake_index; |
| 77 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 78 | bt = &tags->bitmap_tags; |
Alexander Gordeev | 8537b12 | 2014-06-17 22:12:35 -0700 | [diff] [blame] | 79 | wake_index = atomic_read(&bt->wake_index); |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 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 | |
Alexander Gordeev | 8537b12 | 2014-06-17 22:12:35 -0700 | [diff] [blame] | 86 | wake_index = bt_index_inc(wake_index); |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 87 | } |
| 88 | } |
| 89 | |
| 90 | /* |
Jens Axboe | e3a2b3f | 2014-05-20 11:49:02 -0600 | [diff] [blame] | 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 | |
| 106 | /* |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 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 | |
Jens Axboe | e93ecf6 | 2014-05-19 09:17:48 -0600 | [diff] [blame] | 137 | static int __bt_get_word(struct blk_align_bitmap *bm, unsigned int last_tag) |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 138 | { |
| 139 | int tag, org_last_tag, end; |
Bart Van Assche | 9e98e9d | 2014-12-09 16:58:11 +0100 | [diff] [blame] | 140 | bool wrap = last_tag != 0; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 141 | |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 142 | org_last_tag = last_tag; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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 | */ |
Bart Van Assche | 9e98e9d | 2014-12-09 16:58:11 +0100 | [diff] [blame] | 152 | if (wrap) { |
| 153 | wrap = false; |
| 154 | end = org_last_tag; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 155 | last_tag = 0; |
| 156 | goto restart; |
| 157 | } |
| 158 | return -1; |
| 159 | } |
| 160 | last_tag = tag + 1; |
Bart Van Assche | c38d185 | 2014-12-09 16:58:35 +0100 | [diff] [blame] | 161 | } while (test_and_set_bit(tag, &bm->word)); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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 | */ |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 177 | static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt, |
| 178 | unsigned int *tag_cache) |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 179 | { |
| 180 | unsigned int last_tag, org_last_tag; |
| 181 | int index, i, tag; |
| 182 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 183 | if (!hctx_may_queue(hctx, bt)) |
| 184 | return -1; |
| 185 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 186 | last_tag = org_last_tag = *tag_cache; |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 187 | index = TAG_TO_INDEX(bt, last_tag); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 188 | |
| 189 | for (i = 0; i < bt->map_nr; i++) { |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 190 | tag = __bt_get_word(&bt->map[index], TAG_TO_BIT(bt, last_tag)); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 191 | if (tag != -1) { |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 192 | tag += (index << bt->bits_per_word); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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; |
Alexander Gordeev | 8537b12 | 2014-06-17 22:12:35 -0700 | [diff] [blame] | 224 | int wait_index; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 225 | |
| 226 | if (!hctx) |
| 227 | return &bt->bs[0]; |
| 228 | |
Alexander Gordeev | 8537b12 | 2014-06-17 22:12:35 -0700 | [diff] [blame] | 229 | wait_index = atomic_read(&hctx->wait_index); |
| 230 | bs = &bt->bs[wait_index]; |
| 231 | bt_index_atomic_inc(&hctx->wait_index); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 232 | return bs; |
| 233 | } |
| 234 | |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 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) |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 239 | { |
| 240 | struct bt_wait_state *bs; |
| 241 | DEFINE_WAIT(wait); |
| 242 | int tag; |
| 243 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 244 | tag = __bt_get(hctx, bt, last_tag); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 245 | if (tag != -1) |
| 246 | return tag; |
| 247 | |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 248 | if (!(data->gfp & __GFP_WAIT)) |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 249 | return -1; |
| 250 | |
Jens Axboe | 35d37c6 | 2014-12-15 08:30:26 -0700 | [diff] [blame] | 251 | bs = bt_wait_ptr(bt, hctx); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 252 | do { |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 253 | prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE); |
| 254 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 255 | tag = __bt_get(hctx, bt, last_tag); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 256 | if (tag != -1) |
| 257 | break; |
| 258 | |
Bart Van Assche | b322320 | 2014-12-08 08:46:34 -0700 | [diff] [blame] | 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 | |
Jens Axboe | 080ff35 | 2014-12-08 08:49:06 -0700 | [diff] [blame] | 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 | |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 274 | blk_mq_put_ctx(data->ctx); |
| 275 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 276 | io_schedule(); |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 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 | } |
Jens Axboe | 35d37c6 | 2014-12-15 08:30:26 -0700 | [diff] [blame] | 288 | finish_wait(&bs->wait, &wait); |
| 289 | bs = bt_wait_ptr(bt, hctx); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 290 | } while (1); |
| 291 | |
| 292 | finish_wait(&bs->wait, &wait); |
| 293 | return tag; |
| 294 | } |
| 295 | |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 296 | static unsigned int __blk_mq_get_tag(struct blk_mq_alloc_data *data) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 297 | { |
| 298 | int tag; |
| 299 | |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 300 | tag = bt_get(data, &data->hctx->tags->bitmap_tags, data->hctx, |
| 301 | &data->ctx->last_tag); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 302 | if (tag >= 0) |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 303 | return tag + data->hctx->tags->nr_reserved_tags; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 304 | |
| 305 | return BLK_MQ_TAG_FAIL; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 306 | } |
| 307 | |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 308 | static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_alloc_data *data) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 309 | { |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 310 | int tag, zero = 0; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 311 | |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 312 | if (unlikely(!data->hctx->tags->nr_reserved_tags)) { |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 313 | WARN_ON_ONCE(1); |
| 314 | return BLK_MQ_TAG_FAIL; |
| 315 | } |
| 316 | |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 317 | tag = bt_get(data, &data->hctx->tags->breserved_tags, NULL, &zero); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 318 | if (tag < 0) |
| 319 | return BLK_MQ_TAG_FAIL; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 320 | |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 321 | return tag; |
| 322 | } |
| 323 | |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 324 | unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 325 | { |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 326 | if (!data->reserved) |
| 327 | return __blk_mq_get_tag(data); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 328 | |
Ming Lei | cb96a42c | 2014-06-01 00:43:37 +0800 | [diff] [blame] | 329 | return __blk_mq_get_reserved_tag(data); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 330 | } |
| 331 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 332 | static struct bt_wait_state *bt_wake_ptr(struct blk_mq_bitmap_tags *bt) |
| 333 | { |
| 334 | int i, wake_index; |
| 335 | |
Alexander Gordeev | 8537b12 | 2014-06-17 22:12:35 -0700 | [diff] [blame] | 336 | wake_index = atomic_read(&bt->wake_index); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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)) { |
Alexander Gordeev | 8537b12 | 2014-06-17 22:12:35 -0700 | [diff] [blame] | 341 | int o = atomic_read(&bt->wake_index); |
| 342 | if (wake_index != o) |
| 343 | atomic_cmpxchg(&bt->wake_index, o, wake_index); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 344 | |
| 345 | return bs; |
| 346 | } |
| 347 | |
Alexander Gordeev | 8537b12 | 2014-06-17 22:12:35 -0700 | [diff] [blame] | 348 | wake_index = bt_index_inc(wake_index); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 349 | } |
| 350 | |
| 351 | return NULL; |
| 352 | } |
| 353 | |
| 354 | static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag) |
| 355 | { |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 356 | const int index = TAG_TO_INDEX(bt, tag); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 357 | struct bt_wait_state *bs; |
Alexander Gordeev | 2971c35 | 2014-06-12 17:05:37 +0200 | [diff] [blame] | 358 | int wait_cnt; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 359 | |
Bart Van Assche | c38d185 | 2014-12-09 16:58:35 +0100 | [diff] [blame] | 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(); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 364 | |
| 365 | bs = bt_wake_ptr(bt); |
Alexander Gordeev | 2971c35 | 2014-06-12 17:05:37 +0200 | [diff] [blame] | 366 | if (!bs) |
| 367 | return; |
| 368 | |
| 369 | wait_cnt = atomic_dec_return(&bs->wait_cnt); |
Bart Van Assche | 9d8f0bc | 2014-10-07 08:45:21 -0600 | [diff] [blame] | 370 | if (unlikely(wait_cnt < 0)) |
| 371 | wait_cnt = atomic_inc_return(&bs->wait_cnt); |
Alexander Gordeev | 2971c35 | 2014-06-12 17:05:37 +0200 | [diff] [blame] | 372 | if (wait_cnt == 0) { |
Alexander Gordeev | 2971c35 | 2014-06-12 17:05:37 +0200 | [diff] [blame] | 373 | atomic_add(bt->wake_cnt, &bs->wait_cnt); |
Alexander Gordeev | 8537b12 | 2014-06-17 22:12:35 -0700 | [diff] [blame] | 374 | bt_index_atomic_inc(&bt->wake_index); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 375 | wake_up(&bs->wait); |
| 376 | } |
| 377 | } |
| 378 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 379 | void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, unsigned int tag, |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 380 | unsigned int *last_tag) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 381 | { |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 382 | struct blk_mq_tags *tags = hctx->tags; |
| 383 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 384 | if (tag >= tags->nr_reserved_tags) { |
| 385 | const int real_tag = tag - tags->nr_reserved_tags; |
| 386 | |
Jens Axboe | 70114c3 | 2014-11-24 15:52:30 -0700 | [diff] [blame] | 387 | BUG_ON(real_tag >= tags->nr_tags); |
| 388 | bt_clear_tag(&tags->bitmap_tags, real_tag); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 389 | *last_tag = real_tag; |
Jens Axboe | 70114c3 | 2014-11-24 15:52:30 -0700 | [diff] [blame] | 390 | } else { |
| 391 | BUG_ON(tag >= tags->nr_reserved_tags); |
| 392 | bt_clear_tag(&tags->breserved_tags, tag); |
| 393 | } |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 394 | } |
| 395 | |
Christoph Hellwig | 81481eb | 2014-09-13 16:40:11 -0700 | [diff] [blame] | 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) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 399 | { |
Christoph Hellwig | 81481eb | 2014-09-13 16:40:11 -0700 | [diff] [blame] | 400 | struct request *rq; |
| 401 | int bit, i; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 402 | |
| 403 | for (i = 0; i < bt->map_nr; i++) { |
Jens Axboe | e93ecf6 | 2014-05-19 09:17:48 -0600 | [diff] [blame] | 404 | struct blk_align_bitmap *bm = &bt->map[i]; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 405 | |
Christoph Hellwig | 81481eb | 2014-09-13 16:40:11 -0700 | [diff] [blame] | 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 | } |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 413 | |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 414 | off += (1 << bt->bits_per_word); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 415 | } |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 416 | } |
| 417 | |
Christoph Hellwig | 81481eb | 2014-09-13 16:40:11 -0700 | [diff] [blame] | 418 | void blk_mq_tag_busy_iter(struct blk_mq_hw_ctx *hctx, busy_iter_fn *fn, |
| 419 | void *priv) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 420 | { |
Christoph Hellwig | 81481eb | 2014-09-13 16:40:11 -0700 | [diff] [blame] | 421 | struct blk_mq_tags *tags = hctx->tags; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 422 | |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 423 | if (tags->nr_reserved_tags) |
Christoph Hellwig | 81481eb | 2014-09-13 16:40:11 -0700 | [diff] [blame] | 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); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 427 | } |
Sam Bradshaw | edf866b | 2014-05-23 13:30:16 -0600 | [diff] [blame] | 428 | EXPORT_SYMBOL(blk_mq_tag_busy_iter); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 429 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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++) { |
Jens Axboe | e93ecf6 | 2014-05-19 09:17:48 -0600 | [diff] [blame] | 435 | struct blk_align_bitmap *bm = &bt->map[i]; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 436 | |
| 437 | used += bitmap_weight(&bm->word, bm->depth); |
| 438 | } |
| 439 | |
| 440 | return bt->depth - used; |
| 441 | } |
| 442 | |
Jens Axboe | e3a2b3f | 2014-05-20 11:49:02 -0600 | [diff] [blame] | 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; |
Jens Axboe | abab13b | 2014-10-07 08:39:20 -0600 | [diff] [blame] | 459 | if (bt->wake_cnt > depth / BT_WAIT_QUEUES) |
| 460 | bt->wake_cnt = max(1U, depth / BT_WAIT_QUEUES); |
Jens Axboe | e3a2b3f | 2014-05-20 11:49:02 -0600 | [diff] [blame] | 461 | |
| 462 | bt->depth = depth; |
| 463 | } |
| 464 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 465 | static int bt_alloc(struct blk_mq_bitmap_tags *bt, unsigned int depth, |
| 466 | int node, bool reserved) |
| 467 | { |
| 468 | int i; |
| 469 | |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 470 | bt->bits_per_word = ilog2(BITS_PER_LONG); |
| 471 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 472 | /* |
| 473 | * Depth can be zero for reserved tags, that's not a failure |
| 474 | * condition. |
| 475 | */ |
| 476 | if (depth) { |
Jens Axboe | e3a2b3f | 2014-05-20 11:49:02 -0600 | [diff] [blame] | 477 | unsigned int nr, tags_per_word; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 478 | |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 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 | } |
| 493 | |
| 494 | nr = ALIGN(depth, tags_per_word) / tags_per_word; |
Jens Axboe | e93ecf6 | 2014-05-19 09:17:48 -0600 | [diff] [blame] | 495 | bt->map = kzalloc_node(nr * sizeof(struct blk_align_bitmap), |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 496 | GFP_KERNEL, node); |
| 497 | if (!bt->map) |
| 498 | return -ENOMEM; |
| 499 | |
| 500 | bt->map_nr = nr; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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 | |
Jens Axboe | e3a2b3f | 2014-05-20 11:49:02 -0600 | [diff] [blame] | 509 | bt_update_count(bt, depth); |
Alexander Gordeev | 86fb5c5 | 2014-06-17 22:37:23 +0200 | [diff] [blame] | 510 | |
| 511 | for (i = 0; i < BT_WAIT_QUEUES; i++) { |
| 512 | init_waitqueue_head(&bt->bs[i].wait); |
| 513 | atomic_set(&bt->bs[i].wait_cnt, bt->wake_cnt); |
| 514 | } |
| 515 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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 | |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 542 | struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, |
| 543 | unsigned int reserved_tags, int node) |
| 544 | { |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 545 | struct blk_mq_tags *tags; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 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 | |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 556 | tags->nr_tags = total_tags; |
| 557 | tags->nr_reserved_tags = reserved_tags; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 558 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 559 | return blk_mq_init_bitmap_tags(tags, node); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 560 | } |
| 561 | |
| 562 | void blk_mq_free_tags(struct blk_mq_tags *tags) |
| 563 | { |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 564 | bt_free(&tags->bitmap_tags); |
| 565 | bt_free(&tags->breserved_tags); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 566 | kfree(tags); |
| 567 | } |
| 568 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 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 | |
Ming Lei | 9d3d21a | 2014-05-10 15:43:14 -0600 | [diff] [blame] | 573 | *tag = prandom_u32() % depth; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 574 | } |
| 575 | |
Jens Axboe | e3a2b3f | 2014-05-20 11:49:02 -0600 | [diff] [blame] | 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 | |
Bart Van Assche | 205fb5f5 | 2014-10-30 14:45:11 +0100 | [diff] [blame] | 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 | |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 619 | ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page) |
| 620 | { |
| 621 | char *orig_page = page; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 622 | unsigned int free, res; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 623 | |
| 624 | if (!tags) |
| 625 | return 0; |
| 626 | |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 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); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 631 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 632 | free = bt_unused_tags(&tags->bitmap_tags); |
| 633 | res = bt_unused_tags(&tags->breserved_tags); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 634 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 635 | page += sprintf(page, "nr_free=%u, nr_reserved=%u\n", free, res); |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame] | 636 | page += sprintf(page, "active_queues=%u\n", atomic_read(&tags->active_queues)); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 637 | |
| 638 | return page - orig_page; |
| 639 | } |