Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 1 | #include <linux/kernel.h> |
| 2 | #include <linux/module.h> |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 3 | #include <linux/random.h> |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 4 | |
| 5 | #include <linux/blk-mq.h> |
| 6 | #include "blk.h" |
| 7 | #include "blk-mq.h" |
| 8 | #include "blk-mq-tag.h" |
| 9 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 10 | void blk_mq_wait_for_tags(struct blk_mq_hw_ctx *hctx, bool reserved) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 11 | { |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 12 | int tag, zero = 0; |
| 13 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 14 | tag = blk_mq_get_tag(hctx, &zero, __GFP_WAIT, reserved); |
| 15 | blk_mq_put_tag(hctx, tag, &zero); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 16 | } |
| 17 | |
| 18 | static bool bt_has_free_tags(struct blk_mq_bitmap_tags *bt) |
| 19 | { |
| 20 | int i; |
| 21 | |
| 22 | for (i = 0; i < bt->map_nr; i++) { |
| 23 | struct blk_mq_bitmap *bm = &bt->map[i]; |
| 24 | int ret; |
| 25 | |
| 26 | ret = find_first_zero_bit(&bm->word, bm->depth); |
| 27 | if (ret < bm->depth) |
| 28 | return true; |
| 29 | } |
| 30 | |
| 31 | return false; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 32 | } |
| 33 | |
| 34 | bool blk_mq_has_free_tags(struct blk_mq_tags *tags) |
| 35 | { |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 36 | if (!tags) |
| 37 | return true; |
| 38 | |
| 39 | return bt_has_free_tags(&tags->bitmap_tags); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 40 | } |
| 41 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 42 | static inline void bt_index_inc(unsigned int *index) |
| 43 | { |
| 44 | *index = (*index + 1) & (BT_WAIT_QUEUES - 1); |
| 45 | } |
| 46 | |
| 47 | /* |
| 48 | * If a previously inactive queue goes active, bump the active user count. |
| 49 | */ |
| 50 | bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx) |
| 51 | { |
| 52 | if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) && |
| 53 | !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) |
| 54 | atomic_inc(&hctx->tags->active_queues); |
| 55 | |
| 56 | return true; |
| 57 | } |
| 58 | |
| 59 | /* |
| 60 | * If a previously busy queue goes inactive, potential waiters could now |
| 61 | * be allowed to queue. Wake them up and check. |
| 62 | */ |
| 63 | void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx) |
| 64 | { |
| 65 | struct blk_mq_tags *tags = hctx->tags; |
| 66 | struct blk_mq_bitmap_tags *bt; |
| 67 | int i, wake_index; |
| 68 | |
| 69 | if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) |
| 70 | return; |
| 71 | |
| 72 | atomic_dec(&tags->active_queues); |
| 73 | |
| 74 | /* |
| 75 | * Will only throttle depth on non-reserved tags |
| 76 | */ |
| 77 | bt = &tags->bitmap_tags; |
| 78 | wake_index = bt->wake_index; |
| 79 | for (i = 0; i < BT_WAIT_QUEUES; i++) { |
| 80 | struct bt_wait_state *bs = &bt->bs[wake_index]; |
| 81 | |
| 82 | if (waitqueue_active(&bs->wait)) |
| 83 | wake_up(&bs->wait); |
| 84 | |
| 85 | bt_index_inc(&wake_index); |
| 86 | } |
| 87 | } |
| 88 | |
| 89 | /* |
| 90 | * For shared tag users, we track the number of currently active users |
| 91 | * and attempt to provide a fair share of the tag depth for each of them. |
| 92 | */ |
| 93 | static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, |
| 94 | struct blk_mq_bitmap_tags *bt) |
| 95 | { |
| 96 | unsigned int depth, users; |
| 97 | |
| 98 | if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_SHARED)) |
| 99 | return true; |
| 100 | if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) |
| 101 | return true; |
| 102 | |
| 103 | /* |
| 104 | * Don't try dividing an ant |
| 105 | */ |
| 106 | if (bt->depth == 1) |
| 107 | return true; |
| 108 | |
| 109 | users = atomic_read(&hctx->tags->active_queues); |
| 110 | if (!users) |
| 111 | return true; |
| 112 | |
| 113 | /* |
| 114 | * Allow at least some tags |
| 115 | */ |
| 116 | depth = max((bt->depth + users - 1) / users, 4U); |
| 117 | return atomic_read(&hctx->nr_active) < depth; |
| 118 | } |
| 119 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 120 | static int __bt_get_word(struct blk_mq_bitmap *bm, unsigned int last_tag) |
| 121 | { |
| 122 | int tag, org_last_tag, end; |
| 123 | |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 124 | org_last_tag = last_tag; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 125 | end = bm->depth; |
| 126 | do { |
| 127 | restart: |
| 128 | tag = find_next_zero_bit(&bm->word, end, last_tag); |
| 129 | if (unlikely(tag >= end)) { |
| 130 | /* |
| 131 | * We started with an offset, start from 0 to |
| 132 | * exhaust the map. |
| 133 | */ |
| 134 | if (org_last_tag && last_tag) { |
| 135 | end = last_tag; |
| 136 | last_tag = 0; |
| 137 | goto restart; |
| 138 | } |
| 139 | return -1; |
| 140 | } |
| 141 | last_tag = tag + 1; |
| 142 | } while (test_and_set_bit_lock(tag, &bm->word)); |
| 143 | |
| 144 | return tag; |
| 145 | } |
| 146 | |
| 147 | /* |
| 148 | * Straight forward bitmap tag implementation, where each bit is a tag |
| 149 | * (cleared == free, and set == busy). The small twist is using per-cpu |
| 150 | * last_tag caches, which blk-mq stores in the blk_mq_ctx software queue |
| 151 | * contexts. This enables us to drastically limit the space searched, |
| 152 | * without dirtying an extra shared cacheline like we would if we stored |
| 153 | * the cache value inside the shared blk_mq_bitmap_tags structure. On top |
| 154 | * of that, each word of tags is in a separate cacheline. This means that |
| 155 | * multiple users will tend to stick to different cachelines, at least |
| 156 | * until the map is exhausted. |
| 157 | */ |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 158 | static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt, |
| 159 | unsigned int *tag_cache) |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 160 | { |
| 161 | unsigned int last_tag, org_last_tag; |
| 162 | int index, i, tag; |
| 163 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 164 | if (!hctx_may_queue(hctx, bt)) |
| 165 | return -1; |
| 166 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 167 | last_tag = org_last_tag = *tag_cache; |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 168 | index = TAG_TO_INDEX(bt, last_tag); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 169 | |
| 170 | for (i = 0; i < bt->map_nr; i++) { |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 171 | 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] | 172 | if (tag != -1) { |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 173 | tag += (index << bt->bits_per_word); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 174 | goto done; |
| 175 | } |
| 176 | |
| 177 | last_tag = 0; |
| 178 | if (++index >= bt->map_nr) |
| 179 | index = 0; |
| 180 | } |
| 181 | |
| 182 | *tag_cache = 0; |
| 183 | return -1; |
| 184 | |
| 185 | /* |
| 186 | * Only update the cache from the allocation path, if we ended |
| 187 | * up using the specific cached tag. |
| 188 | */ |
| 189 | done: |
| 190 | if (tag == org_last_tag) { |
| 191 | last_tag = tag + 1; |
| 192 | if (last_tag >= bt->depth - 1) |
| 193 | last_tag = 0; |
| 194 | |
| 195 | *tag_cache = last_tag; |
| 196 | } |
| 197 | |
| 198 | return tag; |
| 199 | } |
| 200 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 201 | static struct bt_wait_state *bt_wait_ptr(struct blk_mq_bitmap_tags *bt, |
| 202 | struct blk_mq_hw_ctx *hctx) |
| 203 | { |
| 204 | struct bt_wait_state *bs; |
| 205 | |
| 206 | if (!hctx) |
| 207 | return &bt->bs[0]; |
| 208 | |
| 209 | bs = &bt->bs[hctx->wait_index]; |
| 210 | bt_index_inc(&hctx->wait_index); |
| 211 | return bs; |
| 212 | } |
| 213 | |
| 214 | static int bt_get(struct blk_mq_bitmap_tags *bt, struct blk_mq_hw_ctx *hctx, |
| 215 | unsigned int *last_tag, gfp_t gfp) |
| 216 | { |
| 217 | struct bt_wait_state *bs; |
| 218 | DEFINE_WAIT(wait); |
| 219 | int tag; |
| 220 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 221 | tag = __bt_get(hctx, bt, last_tag); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 222 | if (tag != -1) |
| 223 | return tag; |
| 224 | |
| 225 | if (!(gfp & __GFP_WAIT)) |
| 226 | return -1; |
| 227 | |
| 228 | bs = bt_wait_ptr(bt, hctx); |
| 229 | do { |
| 230 | bool was_empty; |
| 231 | |
| 232 | was_empty = list_empty(&wait.task_list); |
| 233 | prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE); |
| 234 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 235 | tag = __bt_get(hctx, bt, last_tag); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 236 | if (tag != -1) |
| 237 | break; |
| 238 | |
| 239 | if (was_empty) |
| 240 | atomic_set(&bs->wait_cnt, bt->wake_cnt); |
| 241 | |
| 242 | io_schedule(); |
| 243 | } while (1); |
| 244 | |
| 245 | finish_wait(&bs->wait, &wait); |
| 246 | return tag; |
| 247 | } |
| 248 | |
| 249 | static unsigned int __blk_mq_get_tag(struct blk_mq_tags *tags, |
| 250 | struct blk_mq_hw_ctx *hctx, |
| 251 | unsigned int *last_tag, gfp_t gfp) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 252 | { |
| 253 | int tag; |
| 254 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 255 | tag = bt_get(&tags->bitmap_tags, hctx, last_tag, gfp); |
| 256 | if (tag >= 0) |
| 257 | return tag + tags->nr_reserved_tags; |
| 258 | |
| 259 | return BLK_MQ_TAG_FAIL; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 260 | } |
| 261 | |
| 262 | static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_tags *tags, |
| 263 | gfp_t gfp) |
| 264 | { |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 265 | int tag, zero = 0; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 266 | |
| 267 | if (unlikely(!tags->nr_reserved_tags)) { |
| 268 | WARN_ON_ONCE(1); |
| 269 | return BLK_MQ_TAG_FAIL; |
| 270 | } |
| 271 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 272 | tag = bt_get(&tags->breserved_tags, NULL, &zero, gfp); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 273 | if (tag < 0) |
| 274 | return BLK_MQ_TAG_FAIL; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 275 | |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 276 | return tag; |
| 277 | } |
| 278 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 279 | unsigned int blk_mq_get_tag(struct blk_mq_hw_ctx *hctx, unsigned int *last_tag, |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 280 | gfp_t gfp, bool reserved) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 281 | { |
| 282 | if (!reserved) |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 283 | return __blk_mq_get_tag(hctx->tags, hctx, last_tag, gfp); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 284 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 285 | return __blk_mq_get_reserved_tag(hctx->tags, gfp); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 286 | } |
| 287 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 288 | static struct bt_wait_state *bt_wake_ptr(struct blk_mq_bitmap_tags *bt) |
| 289 | { |
| 290 | int i, wake_index; |
| 291 | |
| 292 | wake_index = bt->wake_index; |
| 293 | for (i = 0; i < BT_WAIT_QUEUES; i++) { |
| 294 | struct bt_wait_state *bs = &bt->bs[wake_index]; |
| 295 | |
| 296 | if (waitqueue_active(&bs->wait)) { |
| 297 | if (wake_index != bt->wake_index) |
| 298 | bt->wake_index = wake_index; |
| 299 | |
| 300 | return bs; |
| 301 | } |
| 302 | |
| 303 | bt_index_inc(&wake_index); |
| 304 | } |
| 305 | |
| 306 | return NULL; |
| 307 | } |
| 308 | |
| 309 | static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag) |
| 310 | { |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 311 | const int index = TAG_TO_INDEX(bt, tag); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 312 | struct bt_wait_state *bs; |
| 313 | |
Ming Lei | 0289b2e | 2014-05-11 01:01:48 +0800 | [diff] [blame] | 314 | /* |
| 315 | * The unlock memory barrier need to order access to req in free |
| 316 | * path and clearing tag bit |
| 317 | */ |
| 318 | clear_bit_unlock(TAG_TO_BIT(bt, tag), &bt->map[index].word); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 319 | |
| 320 | bs = bt_wake_ptr(bt); |
| 321 | if (bs && atomic_dec_and_test(&bs->wait_cnt)) { |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 322 | atomic_set(&bs->wait_cnt, bt->wake_cnt); |
| 323 | bt_index_inc(&bt->wake_index); |
| 324 | wake_up(&bs->wait); |
| 325 | } |
| 326 | } |
| 327 | |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 328 | static void __blk_mq_put_tag(struct blk_mq_tags *tags, unsigned int tag) |
| 329 | { |
| 330 | BUG_ON(tag >= tags->nr_tags); |
| 331 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 332 | bt_clear_tag(&tags->bitmap_tags, tag); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 333 | } |
| 334 | |
| 335 | static void __blk_mq_put_reserved_tag(struct blk_mq_tags *tags, |
| 336 | unsigned int tag) |
| 337 | { |
| 338 | BUG_ON(tag >= tags->nr_reserved_tags); |
| 339 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 340 | bt_clear_tag(&tags->breserved_tags, tag); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 341 | } |
| 342 | |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 343 | 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] | 344 | unsigned int *last_tag) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 345 | { |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 346 | struct blk_mq_tags *tags = hctx->tags; |
| 347 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 348 | if (tag >= tags->nr_reserved_tags) { |
| 349 | const int real_tag = tag - tags->nr_reserved_tags; |
| 350 | |
| 351 | __blk_mq_put_tag(tags, real_tag); |
| 352 | *last_tag = real_tag; |
| 353 | } else |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 354 | __blk_mq_put_reserved_tag(tags, tag); |
| 355 | } |
| 356 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 357 | static void bt_for_each_free(struct blk_mq_bitmap_tags *bt, |
| 358 | unsigned long *free_map, unsigned int off) |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 359 | { |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 360 | int i; |
| 361 | |
| 362 | for (i = 0; i < bt->map_nr; i++) { |
| 363 | struct blk_mq_bitmap *bm = &bt->map[i]; |
| 364 | int bit = 0; |
| 365 | |
| 366 | do { |
| 367 | bit = find_next_zero_bit(&bm->word, bm->depth, bit); |
| 368 | if (bit >= bm->depth) |
| 369 | break; |
| 370 | |
| 371 | __set_bit(bit + off, free_map); |
| 372 | bit++; |
| 373 | } while (1); |
| 374 | |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 375 | off += (1 << bt->bits_per_word); |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 376 | } |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 377 | } |
| 378 | |
| 379 | void blk_mq_tag_busy_iter(struct blk_mq_tags *tags, |
| 380 | void (*fn)(void *, unsigned long *), void *data) |
| 381 | { |
| 382 | unsigned long *tag_map; |
| 383 | size_t map_size; |
| 384 | |
| 385 | map_size = ALIGN(tags->nr_tags, BITS_PER_LONG) / BITS_PER_LONG; |
| 386 | tag_map = kzalloc(map_size * sizeof(unsigned long), GFP_ATOMIC); |
| 387 | if (!tag_map) |
| 388 | return; |
| 389 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 390 | bt_for_each_free(&tags->bitmap_tags, tag_map, tags->nr_reserved_tags); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 391 | if (tags->nr_reserved_tags) |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 392 | bt_for_each_free(&tags->breserved_tags, tag_map, 0); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 393 | |
| 394 | fn(data, tag_map); |
| 395 | kfree(tag_map); |
| 396 | } |
| 397 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 398 | static unsigned int bt_unused_tags(struct blk_mq_bitmap_tags *bt) |
| 399 | { |
| 400 | unsigned int i, used; |
| 401 | |
| 402 | for (i = 0, used = 0; i < bt->map_nr; i++) { |
| 403 | struct blk_mq_bitmap *bm = &bt->map[i]; |
| 404 | |
| 405 | used += bitmap_weight(&bm->word, bm->depth); |
| 406 | } |
| 407 | |
| 408 | return bt->depth - used; |
| 409 | } |
| 410 | |
| 411 | static int bt_alloc(struct blk_mq_bitmap_tags *bt, unsigned int depth, |
| 412 | int node, bool reserved) |
| 413 | { |
| 414 | int i; |
| 415 | |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 416 | bt->bits_per_word = ilog2(BITS_PER_LONG); |
| 417 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 418 | /* |
| 419 | * Depth can be zero for reserved tags, that's not a failure |
| 420 | * condition. |
| 421 | */ |
| 422 | if (depth) { |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 423 | unsigned int nr, i, map_depth, tags_per_word; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 424 | |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 425 | tags_per_word = (1 << bt->bits_per_word); |
| 426 | |
| 427 | /* |
| 428 | * If the tag space is small, shrink the number of tags |
| 429 | * per word so we spread over a few cachelines, at least. |
| 430 | * If less than 4 tags, just forget about it, it's not |
| 431 | * going to work optimally anyway. |
| 432 | */ |
| 433 | if (depth >= 4) { |
| 434 | while (tags_per_word * 4 > depth) { |
| 435 | bt->bits_per_word--; |
| 436 | tags_per_word = (1 << bt->bits_per_word); |
| 437 | } |
| 438 | } |
| 439 | |
| 440 | nr = ALIGN(depth, tags_per_word) / tags_per_word; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 441 | bt->map = kzalloc_node(nr * sizeof(struct blk_mq_bitmap), |
| 442 | GFP_KERNEL, node); |
| 443 | if (!bt->map) |
| 444 | return -ENOMEM; |
| 445 | |
| 446 | bt->map_nr = nr; |
| 447 | map_depth = depth; |
| 448 | for (i = 0; i < nr; i++) { |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 449 | bt->map[i].depth = min(map_depth, tags_per_word); |
| 450 | map_depth -= tags_per_word; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 451 | } |
| 452 | } |
| 453 | |
| 454 | bt->bs = kzalloc(BT_WAIT_QUEUES * sizeof(*bt->bs), GFP_KERNEL); |
| 455 | if (!bt->bs) { |
| 456 | kfree(bt->map); |
| 457 | return -ENOMEM; |
| 458 | } |
| 459 | |
| 460 | for (i = 0; i < BT_WAIT_QUEUES; i++) |
| 461 | init_waitqueue_head(&bt->bs[i].wait); |
| 462 | |
| 463 | bt->wake_cnt = BT_WAIT_BATCH; |
| 464 | if (bt->wake_cnt > depth / 4) |
| 465 | bt->wake_cnt = max(1U, depth / 4); |
| 466 | |
| 467 | bt->depth = depth; |
| 468 | return 0; |
| 469 | } |
| 470 | |
| 471 | static void bt_free(struct blk_mq_bitmap_tags *bt) |
| 472 | { |
| 473 | kfree(bt->map); |
| 474 | kfree(bt->bs); |
| 475 | } |
| 476 | |
| 477 | static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, |
| 478 | int node) |
| 479 | { |
| 480 | unsigned int depth = tags->nr_tags - tags->nr_reserved_tags; |
| 481 | |
| 482 | if (bt_alloc(&tags->bitmap_tags, depth, node, false)) |
| 483 | goto enomem; |
| 484 | if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, node, true)) |
| 485 | goto enomem; |
| 486 | |
| 487 | return tags; |
| 488 | enomem: |
| 489 | bt_free(&tags->bitmap_tags); |
| 490 | kfree(tags); |
| 491 | return NULL; |
| 492 | } |
| 493 | |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 494 | struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, |
| 495 | unsigned int reserved_tags, int node) |
| 496 | { |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 497 | struct blk_mq_tags *tags; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 498 | |
| 499 | if (total_tags > BLK_MQ_TAG_MAX) { |
| 500 | pr_err("blk-mq: tag depth too large\n"); |
| 501 | return NULL; |
| 502 | } |
| 503 | |
| 504 | tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node); |
| 505 | if (!tags) |
| 506 | return NULL; |
| 507 | |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 508 | tags->nr_tags = total_tags; |
| 509 | tags->nr_reserved_tags = reserved_tags; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 510 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 511 | return blk_mq_init_bitmap_tags(tags, node); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 512 | } |
| 513 | |
| 514 | void blk_mq_free_tags(struct blk_mq_tags *tags) |
| 515 | { |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 516 | bt_free(&tags->bitmap_tags); |
| 517 | bt_free(&tags->breserved_tags); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 518 | kfree(tags); |
| 519 | } |
| 520 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 521 | void blk_mq_tag_init_last_tag(struct blk_mq_tags *tags, unsigned int *tag) |
| 522 | { |
| 523 | unsigned int depth = tags->nr_tags - tags->nr_reserved_tags; |
| 524 | |
Ming Lei | 9d3d21a | 2014-05-10 15:43:14 -0600 | [diff] [blame] | 525 | *tag = prandom_u32() % depth; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 526 | } |
| 527 | |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 528 | ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page) |
| 529 | { |
| 530 | char *orig_page = page; |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 531 | unsigned int free, res; |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 532 | |
| 533 | if (!tags) |
| 534 | return 0; |
| 535 | |
Jens Axboe | 59d13bf | 2014-05-09 13:41:15 -0600 | [diff] [blame] | 536 | page += sprintf(page, "nr_tags=%u, reserved_tags=%u, " |
| 537 | "bits_per_word=%u\n", |
| 538 | tags->nr_tags, tags->nr_reserved_tags, |
| 539 | tags->bitmap_tags.bits_per_word); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 540 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 541 | free = bt_unused_tags(&tags->bitmap_tags); |
| 542 | res = bt_unused_tags(&tags->breserved_tags); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 543 | |
Jens Axboe | 4bb659b | 2014-05-09 09:36:49 -0600 | [diff] [blame] | 544 | page += sprintf(page, "nr_free=%u, nr_reserved=%u\n", free, res); |
Jens Axboe | 0d2602c | 2014-05-13 15:10:52 -0600 | [diff] [blame^] | 545 | page += sprintf(page, "active_queues=%u\n", atomic_read(&tags->active_queues)); |
Jens Axboe | 320ae51 | 2013-10-24 09:20:05 +0100 | [diff] [blame] | 546 | |
| 547 | return page - orig_page; |
| 548 | } |