diff options
| -rw-r--r-- | MAINTAINERS | 1 | ||||
| -rw-r--r-- | block/Kconfig | 1 | ||||
| -rw-r--r-- | block/blk-mq-tag.c | 463 | ||||
| -rw-r--r-- | block/blk-mq-tag.h | 37 | ||||
| -rw-r--r-- | block/blk-mq.c | 112 | ||||
| -rw-r--r-- | block/blk-mq.h | 9 | ||||
| -rw-r--r-- | include/linux/blk-mq.h | 9 | ||||
| -rw-r--r-- | include/linux/sbitmap.h | 327 | ||||
| -rw-r--r-- | lib/Kconfig | 3 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/sbitmap.c | 301 |
11 files changed, 789 insertions, 476 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 71aa5daeae8f..157b1ca3e19d 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -2451,6 +2451,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git S: Maintained F: block/ F: kernel/trace/blktrace.c +F: lib/sbitmap.c BLOCK2MTD DRIVER M: Joern Engel <joern@lazybastard.org> diff --git a/block/Kconfig b/block/Kconfig index 161491d0a879..5136ad4bb6d5 100644 --- a/block/Kconfig +++ b/block/Kconfig @@ -4,6 +4,7 @@ menuconfig BLOCK bool "Enable the block layer" if EXPERT default y + select SBITMAP help Provide block layer support for the kernel. diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 729bac3a673b..2cbdecd594e9 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -1,12 +1,7 @@ /* - * Fast and scalable bitmap tagging variant. Uses sparser bitmaps spread - * over multiple cachelines to avoid ping-pong between multiple submitters - * or submitter and completer. Uses rolling wakeups to avoid falling of - * the scaling cliff when we run out of tags and have to start putting - * submitters to sleep. - * - * Uses active queue tracking to support fairer distribution of tags - * between multiple submitters when a shared tag map is used. + * Tag allocation using scalable bitmaps. Uses active queue tracking to support + * fairer distribution of tags between multiple submitters when a shared tag map + * is used. * * Copyright (C) 2013-2014 Jens Axboe */ @@ -19,40 +14,12 @@ #include "blk-mq.h" #include "blk-mq-tag.h" -static bool bt_has_free_tags(struct blk_mq_bitmap_tags *bt) -{ - int i; - - for (i = 0; i < bt->map_nr; i++) { - struct blk_align_bitmap *bm = &bt->map[i]; - int ret; - - ret = find_first_zero_bit(&bm->word, bm->depth); - if (ret < bm->depth) - return true; - } - - return false; -} - bool blk_mq_has_free_tags(struct blk_mq_tags *tags) { if (!tags) return true; - return bt_has_free_tags(&tags->bitmap_tags); -} - -static inline int bt_index_inc(int index) -{ - return (index + 1) & (BT_WAIT_QUEUES - 1); -} - -static inline void bt_index_atomic_inc(atomic_t *index) -{ - int old = atomic_read(index); - int new = bt_index_inc(old); - atomic_cmpxchg(index, old, new); + return sbitmap_any_bit_clear(&tags->bitmap_tags.sb); } /* @@ -72,29 +39,9 @@ bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx) */ void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool include_reserve) { - struct blk_mq_bitmap_tags *bt; - int i, wake_index; - - /* - * Make sure all changes prior to this are visible from other CPUs. - */ - smp_mb(); - bt = &tags->bitmap_tags; - wake_index = atomic_read(&bt->wake_index); - for (i = 0; i < BT_WAIT_QUEUES; i++) { - struct bt_wait_state *bs = &bt->bs[wake_index]; - - if (waitqueue_active(&bs->wait)) - wake_up(&bs->wait); - - wake_index = bt_index_inc(wake_index); - } - - if (include_reserve) { - bt = &tags->breserved_tags; - if (waitqueue_active(&bt->bs[0].wait)) - wake_up(&bt->bs[0].wait); - } + sbitmap_queue_wake_all(&tags->bitmap_tags); + if (include_reserve) + sbitmap_queue_wake_all(&tags->breserved_tags); } /* @@ -118,7 +65,7 @@ void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx) * and attempt to provide a fair share of the tag depth for each of them. */ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, - struct blk_mq_bitmap_tags *bt) + struct sbitmap_queue *bt) { unsigned int depth, users; @@ -130,7 +77,7 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, /* * Don't try dividing an ant */ - if (bt->depth == 1) + if (bt->sb.depth == 1) return true; users = atomic_read(&hctx->tags->active_queues); @@ -140,127 +87,42 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, /* * Allow at least some tags */ - depth = max((bt->depth + users - 1) / users, 4U); + depth = max((bt->sb.depth + users - 1) / users, 4U); return atomic_read(&hctx->nr_active) < depth; } -static int __bt_get_word(struct blk_align_bitmap *bm, unsigned int last_tag, - bool nowrap) -{ - int tag, org_last_tag = last_tag; - - while (1) { - tag = find_next_zero_bit(&bm->word, bm->depth, last_tag); - if (unlikely(tag >= bm->depth)) { - /* - * We started with an offset, and we didn't reset the - * offset to 0 in a failure case, so start from 0 to - * exhaust the map. - */ - if (org_last_tag && last_tag && !nowrap) { - last_tag = org_last_tag = 0; - continue; - } - return -1; - } - - if (!test_and_set_bit(tag, &bm->word)) - break; - - last_tag = tag + 1; - if (last_tag >= bm->depth - 1) - last_tag = 0; - } - - return tag; -} - #define BT_ALLOC_RR(tags) (tags->alloc_policy == BLK_TAG_ALLOC_RR) -/* - * Straight forward bitmap tag implementation, where each bit is a tag - * (cleared == free, and set == busy). The small twist is using per-cpu - * last_tag caches, which blk-mq stores in the blk_mq_ctx software queue - * contexts. This enables us to drastically limit the space searched, - * without dirtying an extra shared cacheline like we would if we stored - * the cache value inside the shared blk_mq_bitmap_tags structure. On top - * of that, each word of tags is in a separate cacheline. This means that - * multiple users will tend to stick to different cachelines, at least - * until the map is exhausted. - */ -static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt, +static int __bt_get(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt, unsigned int *tag_cache, struct blk_mq_tags *tags) { - unsigned int last_tag, org_last_tag; - int index, i, tag; + unsigned int last_tag; + int tag; if (!hctx_may_queue(hctx, bt)) return -1; - last_tag = org_last_tag = *tag_cache; - index = TAG_TO_INDEX(bt, last_tag); + last_tag = *tag_cache; + tag = sbitmap_get(&bt->sb, last_tag, BT_ALLOC_RR(tags)); - for (i = 0; i < bt->map_nr; i++) { - tag = __bt_get_word(&bt->map[index], TAG_TO_BIT(bt, last_tag), - BT_ALLOC_RR(tags)); - if (tag != -1) { - tag += (index << bt->bits_per_word); - goto done; - } - - /* - * Jump to next index, and reset the last tag to be the - * first tag of that index - */ - index++; - last_tag = (index << bt->bits_per_word); - - if (index >= bt->map_nr) { - index = 0; - last_tag = 0; - } - } - - *tag_cache = 0; - return -1; - - /* - * Only update the cache from the allocation path, if we ended - * up using the specific cached tag. - */ -done: - if (tag == org_last_tag || unlikely(BT_ALLOC_RR(tags))) { + if (tag == -1) { + *tag_cache = 0; + } else if (tag == last_tag || unlikely(BT_ALLOC_RR(tags))) { last_tag = tag + 1; - if (last_tag >= bt->depth - 1) + if (last_tag >= bt->sb.depth - 1) last_tag = 0; - *tag_cache = last_tag; } return tag; } -static struct bt_wait_state *bt_wait_ptr(struct blk_mq_bitmap_tags *bt, - struct blk_mq_hw_ctx *hctx) -{ - struct bt_wait_state *bs; - int wait_index; - - if (!hctx) - return &bt->bs[0]; - - wait_index = atomic_read(&hctx->wait_index); - bs = &bt->bs[wait_index]; - bt_index_atomic_inc(&hctx->wait_index); - return bs; -} - static int bt_get(struct blk_mq_alloc_data *data, - struct blk_mq_bitmap_tags *bt, - struct blk_mq_hw_ctx *hctx, - unsigned int *last_tag, struct blk_mq_tags *tags) + struct sbitmap_queue *bt, + struct blk_mq_hw_ctx *hctx, + unsigned int *last_tag, struct blk_mq_tags *tags) { - struct bt_wait_state *bs; + struct sbq_wait_state *ws; DEFINE_WAIT(wait); int tag; @@ -271,9 +133,9 @@ static int bt_get(struct blk_mq_alloc_data *data, if (data->flags & BLK_MQ_REQ_NOWAIT) return -1; - bs = bt_wait_ptr(bt, hctx); + ws = bt_wait_ptr(bt, hctx); do { - prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE); + prepare_to_wait(&ws->wait, &wait, TASK_UNINTERRUPTIBLE); tag = __bt_get(hctx, bt, last_tag, tags); if (tag != -1) @@ -310,11 +172,11 @@ static int bt_get(struct blk_mq_alloc_data *data, hctx = data->hctx; bt = &hctx->tags->bitmap_tags; } - finish_wait(&bs->wait, &wait); - bs = bt_wait_ptr(bt, hctx); + finish_wait(&ws->wait, &wait); + ws = bt_wait_ptr(bt, hctx); } while (1); - finish_wait(&bs->wait, &wait); + finish_wait(&ws->wait, &wait); return tag; } @@ -354,53 +216,6 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) return __blk_mq_get_tag(data); } -static struct bt_wait_state *bt_wake_ptr(struct blk_mq_bitmap_tags *bt) -{ - int i, wake_index; - - wake_index = atomic_read(&bt->wake_index); - for (i = 0; i < BT_WAIT_QUEUES; i++) { - struct bt_wait_state *bs = &bt->bs[wake_index]; - - if (waitqueue_active(&bs->wait)) { - int o = atomic_read(&bt->wake_index); - if (wake_index != o) - atomic_cmpxchg(&bt->wake_index, o, wake_index); - - return bs; - } - - wake_index = bt_index_inc(wake_index); - } - - return NULL; -} - -static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag) -{ - const int index = TAG_TO_INDEX(bt, tag); - struct bt_wait_state *bs; - int wait_cnt; - - clear_bit(TAG_TO_BIT(bt, tag), &bt->map[index].word); - - /* Ensure that the wait list checks occur after clear_bit(). */ - smp_mb(); - - bs = bt_wake_ptr(bt); - if (!bs) - return; - - wait_cnt = atomic_dec_return(&bs->wait_cnt); - if (unlikely(wait_cnt < 0)) - wait_cnt = atomic_inc_return(&bs->wait_cnt); - if (wait_cnt == 0) { - atomic_add(bt->wake_cnt, &bs->wait_cnt); - bt_index_atomic_inc(&bt->wake_index); - wake_up(&bs->wait); - } -} - void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, unsigned int tag, unsigned int *last_tag) { @@ -410,67 +225,94 @@ void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, unsigned int tag, const int real_tag = tag - tags->nr_reserved_tags; BUG_ON(real_tag >= tags->nr_tags); - bt_clear_tag(&tags->bitmap_tags, real_tag); + sbitmap_queue_clear(&tags->bitmap_tags, real_tag); if (likely(tags->alloc_policy == BLK_TAG_ALLOC_FIFO)) *last_tag = real_tag; } else { BUG_ON(tag >= tags->nr_reserved_tags); - bt_clear_tag(&tags->breserved_tags, tag); + sbitmap_queue_clear(&tags->breserved_tags, tag); } } -static void bt_for_each(struct blk_mq_hw_ctx *hctx, - struct blk_mq_bitmap_tags *bt, unsigned int off, - busy_iter_fn *fn, void *data, bool reserved) +struct bt_iter_data { + struct blk_mq_hw_ctx *hctx; + busy_iter_fn *fn; + void *data; + bool reserved; +}; + +static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) { + struct bt_iter_data *iter_data = data; + struct blk_mq_hw_ctx *hctx = iter_data->hctx; + struct blk_mq_tags *tags = hctx->tags; + bool reserved = iter_data->reserved; struct request *rq; - int bit, i; - for (i = 0; i < bt->map_nr; i++) { - struct blk_align_bitmap *bm = &bt->map[i]; + if (!reserved) + bitnr += tags->nr_reserved_tags; + rq = tags->rqs[bitnr]; - for (bit = find_first_bit(&bm->word, bm->depth); - bit < bm->depth; - bit = find_next_bit(&bm->word, bm->depth, bit + 1)) { - rq = hctx->tags->rqs[off + bit]; - if (rq->q == hctx->queue) - fn(hctx, rq, data, reserved); - } + if (rq->q == hctx->queue) + iter_data->fn(hctx, rq, iter_data->data, reserved); + return true; +} - off += (1 << bt->bits_per_word); - } +static void bt_for_each(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt, + busy_iter_fn *fn, void *data, bool reserved) +{ + struct bt_iter_data iter_data = { + .hctx = hctx, + .fn = fn, + .data = data, + .reserved = reserved, + }; + + sbitmap_for_each_set(&bt->sb, bt_iter, &iter_data); } -static void bt_tags_for_each(struct blk_mq_tags *tags, - struct blk_mq_bitmap_tags *bt, unsigned int off, - busy_tag_iter_fn *fn, void *data, bool reserved) +struct bt_tags_iter_data { + struct blk_mq_tags *tags; + busy_tag_iter_fn *fn; + void *data; + bool reserved; +}; + +static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) { + struct bt_tags_iter_data *iter_data = data; + struct blk_mq_tags *tags = iter_data->tags; + bool reserved = iter_data->reserved; struct request *rq; - int bit, i; - if (!tags->rqs) - return; - for (i = 0; i < bt->map_nr; i++) { - struct blk_align_bitmap *bm = &bt->map[i]; - - for (bit = find_first_bit(&bm->word, bm->depth); - bit < bm->depth; - bit = find_next_bit(&bm->word, bm->depth, bit + 1)) { - rq = tags->rqs[off + bit]; - fn(rq, data, reserved); - } + if (!reserved) + bitnr += tags->nr_reserved_tags; + rq = tags->rqs[bitnr]; - off += (1 << bt->bits_per_word); - } + iter_data->fn(rq, iter_data->data, reserved); + return true; +} + +static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt, + busy_tag_iter_fn *fn, void *data, bool reserved) +{ + struct bt_tags_iter_data iter_data = { + .tags = tags, + .fn = fn, + .data = data, + .reserved = reserved, + }; + + if (tags->rqs) + sbitmap_for_each_set(&bt->sb, bt_tags_iter, &iter_data); } static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn, void *priv) { if (tags->nr_reserved_tags) - bt_tags_for_each(tags, &tags->breserved_tags, 0, fn, priv, true); - bt_tags_for_each(tags, &tags->bitmap_tags, tags->nr_reserved_tags, fn, priv, - false); + bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true); + bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false); } void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset, @@ -529,107 +371,20 @@ void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, continue; if (tags->nr_reserved_tags) - bt_for_each(hctx, &tags->breserved_tags, 0, fn, priv, true); - bt_for_each(hctx, &tags->bitmap_tags, tags->nr_reserved_tags, fn, priv, - false); - } - -} - -static unsigned int bt_unused_tags(struct blk_mq_bitmap_tags *bt) -{ - unsigned int i, used; - - for (i = 0, used = 0; i < bt->map_nr; i++) { - struct blk_align_bitmap *bm = &bt->map[i]; - - used += bitmap_weight(&bm->word, bm->depth); + bt_for_each(hctx, &tags->breserved_tags, fn, priv, true); + bt_for_each(hctx, &tags->bitmap_tags, fn, priv, false); } - return bt->depth - used; } -static void bt_update_count(struct blk_mq_bitmap_tags *bt, - unsigned int depth) +static unsigned int bt_unused_tags(const struct sbitmap_queue *bt) { - unsigned int tags_per_word = 1U << bt->bits_per_word; - unsigned int map_depth = depth; - - if (depth) { - int i; - - for (i = 0; i < bt->map_nr; i++) { - bt->map[i].depth = min(map_depth, tags_per_word); - map_depth -= bt->map[i].depth; - } - } - - bt->wake_cnt = BT_WAIT_BATCH; - if (bt->wake_cnt > depth / BT_WAIT_QUEUES) - bt->wake_cnt = max(1U, depth / BT_WAIT_QUEUES); - - bt->depth = depth; + return bt->sb.depth - sbitmap_weight(&bt->sb); } -static int bt_alloc(struct blk_mq_bitmap_tags *bt, unsigned int depth, - int node, bool reserved) +static int bt_alloc(struct sbitmap_queue *bt, unsigned int depth, int node) { - int i; - - bt->bits_per_word = ilog2(BITS_PER_LONG); - - /* - * Depth can be zero for reserved tags, that's not a failure - * condition. - */ - if (depth) { - unsigned int nr, tags_per_word; - - tags_per_word = (1 << bt->bits_per_word); - - /* - * If the tag space is small, shrink the number of tags - * per word so we spread over a few cachelines, at least. - * If less than 4 tags, just forget about it, it's not - * going to work optimally anyway. - */ - if (depth >= 4) { - while (tags_per_word * 4 > depth) { - bt->bits_per_word--; - tags_per_word = (1 << bt->bits_per_word); - } - } - - nr = ALIGN(depth, tags_per_word) / tags_per_word; - bt->map = kzalloc_node(nr * sizeof(struct blk_align_bitmap), - GFP_KERNEL, node); - if (!bt->map) - return -ENOMEM; - - bt->map_nr = nr; - } - - bt->bs = kzalloc(BT_WAIT_QUEUES * sizeof(*bt->bs), GFP_KERNEL); - if (!bt->bs) { - kfree(bt->map); - bt->map = NULL; - return -ENOMEM; - } - - bt_update_count(bt, depth); - - for (i = 0; i < BT_WAIT_QUEUES; i++) { - init_waitqueue_head(&bt->bs[i].wait); - atomic_set(&bt->bs[i].wait_cnt, bt->wake_cnt); - } - - return 0; -} - -static void bt_free(struct blk_mq_bitmap_tags *bt) -{ - kfree(bt->map); - kfree(bt->bs); + return sbitmap_queue_init_node(bt, depth, -1, GFP_KERNEL, node); } static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, @@ -639,14 +394,15 @@ static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, tags->alloc_policy = alloc_policy; - if (bt_alloc(&tags->bitmap_tags, depth, node, false)) - goto enomem; - if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, node, true)) - goto enomem; + if (bt_alloc(&tags->bitmap_tags, depth, node)) + goto free_tags; + if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, node)) + goto free_bitmap_tags; return tags; -enomem: - bt_free(&tags->bitmap_tags); +free_bitmap_tags: + sbitmap_queue_free(&tags->bitmap_tags); +free_tags: kfree(tags); return NULL; } @@ -679,8 +435,8 @@ struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, void blk_mq_free_tags(struct blk_mq_tags *tags) { - bt_free(&tags->bitmap_tags); - bt_free(&tags->breserved_tags); + sbitmap_queue_free(&tags->bitmap_tags); + sbitmap_queue_free(&tags->breserved_tags); free_cpumask_var(tags->cpumask); kfree(tags); } @@ -702,7 +458,8 @@ int blk_mq_tag_update_depth(struct blk_mq_tags *tags, unsigned int tdepth) * Don't need (or can't) update reserved tags here, they remain * static and should never need resizing. */ - bt_update_count(&tags->bitmap_tags, tdepth); + sbitmap_queue_resize(&tags->bitmap_tags, tdepth); + blk_mq_tag_wakeup_all(tags, false); return 0; } @@ -746,7 +503,7 @@ ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page) page += sprintf(page, "nr_tags=%u, reserved_tags=%u, " "bits_per_word=%u\n", tags->nr_tags, tags->nr_reserved_tags, - tags->bitmap_tags.bits_per_word); + 1U << tags->bitmap_tags.sb.shift); free = bt_unused_tags(&tags->bitmap_tags); res = bt_unused_tags(&tags->breserved_tags); diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h index d468a79f2c4a..3215c08c63cc 100644 --- a/block/blk-mq-tag.h +++ b/block/blk-mq-tag.h @@ -3,31 +3,6 @@ #include "blk-mq.h" -enum { - BT_WAIT_QUEUES = 8, - BT_WAIT_BATCH = 8, -}; - -struct bt_wait_state { - atomic_t wait_cnt; - wait_queue_head_t wait; -} ____cacheline_aligned_in_smp; - -#define TAG_TO_INDEX(bt, tag) ((tag) >> (bt)->bits_per_word) -#define TAG_TO_BIT(bt, tag) ((tag) & ((1 << (bt)->bits_per_word) - 1)) - -struct blk_mq_bitmap_tags { - unsigned int depth; - unsigned int wake_cnt; - unsigned int bits_per_word; - - unsigned int map_nr; - struct blk_align_bitmap *map; - - atomic_t wake_index; - struct bt_wait_state *bs; -}; - /* * Tag address space map. */ @@ -37,8 +12,8 @@ struct blk_mq_tags { atomic_t active_queues; - struct blk_mq_bitmap_tags bitmap_tags; - struct blk_mq_bitmap_tags breserved_tags; + struct sbitmap_queue bitmap_tags; + struct sbitmap_queue breserved_tags; struct request **rqs; struct list_head page_list; @@ -61,6 +36,14 @@ extern void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool); void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, void *priv); +static inline struct sbq_wait_state *bt_wait_ptr(struct sbitmap_queue *bt, + struct blk_mq_hw_ctx *hctx) +{ + if (!hctx) + return &bt->ws[0]; + return sbq_wait_ptr(bt, &hctx->wait_index); +} + enum { BLK_MQ_TAG_CACHE_MIN = 1, BLK_MQ_TAG_CACHE_MAX = 64, diff --git a/block/blk-mq.c b/block/blk-mq.c index 0cb93625d812..6603be18064e 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -41,42 +41,23 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx); */ static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx) { - unsigned int i; - - for (i = 0; i < hctx->ctx_map.size; i++) - if (hctx->ctx_map.map[i].word) - return true; - - return false; -} - -static inline struct blk_align_bitmap *get_bm(struct blk_mq_hw_ctx *hctx, - struct blk_mq_ctx *ctx) -{ - return &hctx->ctx_map.map[ctx->index_hw / hctx->ctx_map.bits_per_word]; + return sbitmap_any_bit_set(&hctx->ctx_map); } -#define CTX_TO_BIT(hctx, ctx) \ - ((ctx)->index_hw & ((hctx)->ctx_map.bits_per_word - 1)) - /* * Mark this ctx as having pending work in this hardware queue */ static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx) { - struct blk_align_bitmap *bm = get_bm(hctx, ctx); - - if (!test_bit(CTX_TO_BIT(hctx, ctx), &bm->word)) - set_bit(CTX_TO_BIT(hctx, ctx), &bm->word); + if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw)) + sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw); } static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx) { - struct blk_align_bitmap *bm = get_bm(hctx, ctx); - - clear_bit(CTX_TO_BIT(hctx, ctx), &bm->word); + sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw); } void blk_mq_freeze_queue_start(struct request_queue *q) @@ -755,38 +736,36 @@ static bool blk_mq_attempt_merge(struct request_queue *q, return false; } +struct flush_busy_ctx_data { + struct blk_mq_hw_ctx *hctx; + struct list_head *list; +}; + +static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data) +{ + struct flush_busy_ctx_data *flush_data = data; + struct blk_mq_hw_ctx *hctx = flush_data->hctx; + struct blk_mq_ctx *ctx = hctx->ctxs[bitnr]; + + sbitmap_clear_bit(sb, bitnr); + spin_lock(&ctx->lock); + list_splice_tail_init(&ctx->rq_list, flush_data->list); + spin_unlock(&ctx->lock); + return true; +} + /* * Process software queues that have been marked busy, splicing them * to the for-dispatch */ static void flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list) { - struct blk_mq_ctx *ctx; - int i; - - for (i = 0; i < hctx->ctx_map.size; i++) { - struct blk_align_bitmap *bm = &hctx->ctx_map.map[i]; - unsigned int off, bit; - - if (!bm->word) - continue; - - bit = 0; - off = i * hctx->ctx_map.bits_per_word; - do { - bit = find_next_bit(&bm->word, bm->depth, bit); - if (bit >= bm->depth) - break; - - ctx = hctx->ctxs[bit + off]; - clear_bit(bit, &bm->word); - spin_lock(&ctx->lock); - list_splice_tail_init(&ctx->rq_list, list); - spin_unlock(&ctx->lock); + struct flush_busy_ctx_data data = { + .hctx = hctx, + .list = list, + }; - bit++; - } while (1); - } + sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data); } static inline unsigned int queued_to_index(unsigned int queued) @@ -1609,32 +1588,6 @@ fail: return NULL; } -static void blk_mq_free_bitmap(struct blk_mq_ctxmap *bitmap) -{ - kfree(bitmap->map); -} - -static int blk_mq_alloc_bitmap(struct blk_mq_ctxmap *bitmap, int node) -{ - unsigned int bpw = 8, total, num_maps, i; - - bitmap->bits_per_word = bpw; - - num_maps = ALIGN(nr_cpu_ids, bpw) / bpw; - bitmap->map = kzalloc_node(num_maps * sizeof(struct blk_align_bitmap), - GFP_KERNEL, node); - if (!bitmap->map) - return -ENOMEM; - - total = nr_cpu_ids; - for (i = 0; i < num_maps; i++) { - bitmap->map[i].depth = min(total, bitmap->bits_per_word); - total -= bitmap->map[i].depth; - } - - return 0; -} - /* * 'cpu' is going away. splice any existing rq_list entries from this * software queue to the hw queue dispatch list, and ensure that it @@ -1700,7 +1653,7 @@ static void blk_mq_exit_hctx(struct request_queue *q, blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier); blk_free_flush_queue(hctx->fq); - blk_mq_free_bitmap(&hctx->ctx_map); + sbitmap_free(&hctx->ctx_map); } static void blk_mq_exit_hw_queues(struct request_queue *q, @@ -1760,7 +1713,8 @@ static int blk_mq_init_hctx(struct request_queue *q, if (!hctx->ctxs) goto unregister_cpu_notifier; - if (blk_mq_alloc_bitmap(&hctx->ctx_map, node)) + if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL, + node)) goto free_ctxs; hctx->nr_ctx = 0; @@ -1787,7 +1741,7 @@ static int blk_mq_init_hctx(struct request_queue *q, if (set->ops->exit_hctx) set->ops->exit_hctx(hctx, hctx_idx); free_bitmap: - blk_mq_free_bitmap(&hctx->ctx_map); + sbitmap_free(&hctx->ctx_map); free_ctxs: kfree(hctx->ctxs); unregister_cpu_notifier: @@ -1863,8 +1817,6 @@ static void blk_mq_map_swqueue(struct request_queue *q, mutex_unlock(&q->sysfs_lock); queue_for_each_hw_ctx(q, hctx, i) { - struct blk_mq_ctxmap *map = &hctx->ctx_map; - /* * If no software queues are mapped to this hardware queue, * disable it and free the request entries. @@ -1890,7 +1842,7 @@ static void blk_mq_map_swqueue(struct request_queue *q, * This is more accurate and more efficient than looping * over all possibly mapped software queues. */ - map->size = DIV_ROUND_UP(hctx->nr_ctx, map->bits_per_word); + sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx); /* * Initialize batch roundrobin counts diff --git a/block/blk-mq.h b/block/blk-mq.h index 9087b11037b7..71831f970fd3 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -63,15 +63,6 @@ extern void blk_mq_rq_timed_out(struct request *req, bool reserved); void blk_mq_release(struct request_queue *q); -/* - * Basic implementation of sparser bitmap, allowing the user to spread - * the bits over more cachelines. - */ -struct blk_align_bitmap { - unsigned long word; - unsigned long depth; -} ____cacheline_aligned_in_smp; - static inline struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q, unsigned int cpu) { diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 60ef14cbcd2d..2575779cf13f 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -2,6 +2,7 @@ #define BLK_MQ_H #include <linux/blkdev.h> +#include <linux/sbitmap.h> struct blk_mq_tags; struct blk_flush_queue; @@ -12,12 +13,6 @@ struct blk_mq_cpu_notifier { int (*notify)(void *data, unsigned long action, unsigned int cpu); }; -struct blk_mq_ctxmap { - unsigned int size; - unsigned int bits_per_word; - struct blk_align_bitmap *map; -}; - struct blk_mq_hw_ctx { struct { spinlock_t lock; @@ -37,7 +32,7 @@ struct blk_mq_hw_ctx { void *driver_data; - struct blk_mq_ctxmap ctx_map; + struct sbitmap ctx_map; struct blk_mq_ctx **ctxs; unsigned int nr_ctx; diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h new file mode 100644 index 000000000000..1a3b836042e1 --- /dev/null +++ b/include/linux/sbitmap.h @@ -0,0 +1,327 @@ +/* + * Fast and scalable bitmaps. + * + * Copyright (C) 2016 Facebook + * Copyright (C) 2013-2014 Jens Axboe + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ + +#ifndef __LINUX_SCALE_BITMAP_H +#define __LINUX_SCALE_BITMAP_H + +#include <linux/kernel.h> +#include <linux/slab.h> + +/** + * struct sbitmap_word - Word in a &struct sbitmap. + */ +struct sbitmap_word { + /** + * @word: The bitmap word itself. + */ + unsigned long word; + + /** + * @depth: Number of bits being used in @word. + */ + unsigned long depth; +} ____cacheline_aligned_in_smp; + +/** + * struct sbitmap - Scalable bitmap. + * + * A &struct sbitmap is spread over multiple cachelines to avoid ping-pong. This + * trades off higher memory usage for better scalability. + */ +struct sbitmap { + /** + * @depth: Number of bits used in the whole bitmap. + */ + unsigned int depth; + + /** + * @shift: log2(number of bits used per word) + */ + unsigned int shift; + + /** + * @map_nr: Number of words (cachelines) being used for the bitmap. + */ + unsigned int map_nr; + + /** + * @map: Allocated bitmap. + */ + struct sbitmap_word *map; +}; + +#define SBQ_WAIT_QUEUES 8 +#define SBQ_WAKE_BATCH 8 + +/** + * struct sbq_wait_state - Wait queue in a &struct sbitmap_queue. + */ +struct sbq_wait_state { + /** + * @wait_cnt: Number of frees remaining before we wake up. + */ + atomic_t wait_cnt; + + /** + * @wait: Wait queue. + */ + wait_queue_head_t wait; +} ____cacheline_aligned_in_smp; + +/** + * struct sbitmap_queue - Scalable bitmap with the added ability to wait on free + * bits. + * + * A &struct sbitmap_queue uses multiple wait queues and rolling wakeups to + * avoid contention on the wait queue spinlock. This ensures that we don't hit a + * scalability wall when we run out of free bits and have to start putting tasks + * to sleep. + */ +struct sbitmap_queue { + /** + * @sb: Scalable bitmap. + */ + struct sbitmap sb; + + /** + * @wake_batch: Number of bits which must be freed before we wake up any + * waiters. + */ + unsigned int wake_batch; + + /** + * @wake_index: Next wait queue in @ws to wake up. + */ + atomic_t wake_index; + + /** + * @ws: Wait queues. + */ + struct sbq_wait_state *ws; +}; + +/** + * sbitmap_init_node() - Initialize a &struct sbitmap on a specific memory node. + * @sb: Bitmap to initialize. + * @depth: Number of bits to allocate. + * @shift: Use 2^@shift bits per word in the bitmap; if a negative number if + * given, a good default is chosen. + * @flags: Allocation flags. + * @node: Memory node to allocate on. + * + * Return: Zero on success or negative errno on failure. + */ +int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift, + gfp_t flags, int node); + +/** + * sbitmap_free() - Free memory used by a &struct sbitmap. + * @sb: Bitmap to free. + */ +static inline void sbitmap_free(struct sbitmap *sb) +{ + kfree(sb->map); + sb->map = NULL; +} + +/** + * sbitmap_resize() - Resize a &struct sbitmap. + * @sb: Bitmap to resize. + * @depth: New number of bits to resize to. + * + * Doesn't reallocate anything. It's up to the caller to ensure that the new + * depth doesn't exceed the depth that the sb was initialized with. + */ +void sbitmap_resize(struct sbitmap *sb, unsigned int depth); + +/** + * sbitmap_get() - Try to allocate a free bit from a &struct sbitmap. + * @sb: Bitmap to allocate from. + * @alloc_hint: Hint for where to start searching for a free bit. + * @round_robin: If true, be stricter about allocation order; always allocate + * starting from the last allocated bit. This is less efficient + * than the default behavior (false). + * + * Return: Non-negative allocated bit number if successful, -1 otherwise. + */ +int sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint, bool round_robin); + +/** + * sbitmap_any_bit_set() - Check for a set bit in a &struct sbitmap. + * @sb: Bitmap to check. + * + * Return: true if any bit in the bitmap is set, false otherwise. + */ +bool sbitmap_any_bit_set(const struct sbitmap *sb); + +/** + * sbitmap_any_bit_clear() - Check for an unset bit in a &struct + * sbitmap. + * @sb: Bitmap to check. + * + * Return: true if any bit in the bitmap is clear, false otherwise. + */ +bool sbitmap_any_bit_clear(const struct sbitmap *sb); + +typedef bool (*sb_for_each_fn)(struct sbitmap *, unsigned int, void *); + +/** + * sbitmap_for_each_set() - Iterate over each set bit in a &struct sbitmap. + * @sb: Bitmap to iterate over. + * @fn: Callback. Should return true to continue or false to break early. + * @data: Pointer to pass to callback. + * + * This is inline even though it's non-trivial so that the function calls to the + * callback will hopefully get optimized away. + */ +static inline void sbitmap_for_each_set(struct sbitmap *sb, sb_for_each_fn fn, + void *data) +{ + unsigned int i; + + for (i = 0; i < sb->map_nr; i++) { + struct sbitmap_word *word = &sb->map[i]; + unsigned int off, nr; + + if (!word->word) + continue; + + nr = 0; + off = i << sb->shift; + while (1) { + nr = find_next_bit(&word->word, word->depth, nr); + if (nr >= word->depth) + break; + + if (!fn(sb, off + nr, data)) + return; + + nr++; + } + } +} + +#define SB_NR_TO_INDEX(sb, bitnr) ((bitnr) >> (sb)->shift) +#define SB_NR_TO_BIT(sb, bitnr) ((bitnr) & ((1U << (sb)->shift) - 1U)) + +static inline unsigned long *__sbitmap_word(struct sbitmap *sb, + unsigned int bitnr) +{ + return &sb->map[SB_NR_TO_INDEX(sb, bitnr)].word; +} + +/* Helpers equivalent to the operations in asm/bitops.h and linux/bitmap.h */ + +static inline void sbitmap_set_bit(struct sbitmap *sb, unsigned int bitnr) +{ + set_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr)); +} + +static inline void sbitmap_clear_bit(struct sbitmap *sb, unsigned int bitnr) +{ + clear_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr)); +} + +static inline int sbitmap_test_bit(struct sbitmap *sb, unsigned int bitnr) +{ + return test_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr)); +} + +unsigned int sbitmap_weight(const struct sbitmap *sb); + +/** + * sbitmap_queue_init_node() - Initialize a &struct sbitmap_queue on a specific + * memory node. + * @sbq: Bitmap queue to initialize. + * @depth: See sbitmap_init_node(). + * @shift: See sbitmap_init_node(). + * @flags: Allocation flags. + * @node: Memory node to allocate on. + * + * Return: Zero on success or negative errno on failure. + */ +int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth, + int shift, gfp_t flags, int node); + +/** + * sbitmap_queue_free() - Free memory used by a &struct sbitmap_queue. + * + * @sbq: Bitmap queue to free. + */ +static inline void sbitmap_queue_free(struct sbitmap_queue *sbq) +{ + kfree(sbq->ws); + sbitmap_free(&sbq->sb); +} + +/** + * sbitmap_queue_resize() - Resize a &struct sbitmap_queue. + * @sbq: Bitmap queue to resize. + * @depth: New number of bits to resize to. + * + * Like sbitmap_resize(), this doesn't reallocate anything. It has to do + * some extra work on the &struct sbitmap_queue, so it's not safe to just + * resize the underlying &struct sbitmap. + */ +void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth); + +/** + * sbitmap_queue_clear() - Free an allocated bit and wake up waiters on a + * &struct sbitmap_queue. + * @sbq: Bitmap to free from. + * @nr: Bit number to free. + */ +void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr); + +static inline int sbq_index_inc(int index) +{ + return (index + 1) & (SBQ_WAIT_QUEUES - 1); +} + +static inline void sbq_index_atomic_inc(atomic_t *index) +{ + int old = atomic_read(index); + int new = sbq_index_inc(old); + atomic_cmpxchg(index, old, new); +} + +/** + * sbq_wait_ptr() - Get the next wait queue to use for a &struct + * sbitmap_queue. + * @sbq: Bitmap queue to wait on. + * @wait_index: A counter per "user" of @sbq. + */ +static inline struct sbq_wait_state *sbq_wait_ptr(struct sbitmap_queue *sbq, + atomic_t *wait_index) +{ + struct sbq_wait_state *ws; + + ws = &sbq->ws[atomic_read(wait_index)]; + sbq_index_atomic_inc(wait_index); + return ws; +} + +/** + * sbitmap_queue_wake_all() - Wake up everything waiting on a &struct + * sbitmap_queue. + * @sbq: Bitmap queue to wake up. + */ +void sbitmap_queue_wake_all(struct sbitmap_queue *sbq); + +#endif /* __LINUX_SCALE_BITMAP_H */ diff --git a/lib/Kconfig b/lib/Kconfig index d79909dc01ec..942fb8091a86 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -550,4 +550,7 @@ config STACKDEPOT bool select STACKTRACE +config SBITMAP + bool + endmenu diff --git a/lib/Makefile b/lib/Makefile index cfa68eb269e4..2cbfd2904994 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -228,3 +228,5 @@ obj-$(CONFIG_UCS2_STRING) += ucs2_string.o obj-$(CONFIG_UBSAN) += ubsan.o UBSAN_SANITIZE_ubsan.o := n + +obj-$(CONFIG_SBITMAP) += sbitmap.o diff --git a/lib/sbitmap.c b/lib/sbitmap.c new file mode 100644 index 000000000000..dfc084ac6937 --- /dev/null +++ b/lib/sbitmap.c @@ -0,0 +1,301 @@ +/* + * Copyright (C) 2016 Facebook + * Copyright (C) 2013-2014 Jens Axboe + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ + +#include <linux/sbitmap.h> + +int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift, + gfp_t flags, int node) +{ + unsigned int bits_per_word; + unsigned int i; + + if (shift < 0) { + shift = ilog2(BITS_PER_LONG); + /* + * If the bitmap is small, shrink the number of bits per word so + * we spread over a few cachelines, at least. If less than 4 + * bits, just forget about it, it's not going to work optimally + * anyway. + */ + if (depth >= 4) { + while ((4U << shift) > depth) + shift--; + } + } + bits_per_word = 1U << shift; + if (bits_per_word > BITS_PER_LONG) + return -EINVAL; + + sb->shift = shift; + sb->depth = depth; + sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word); + + if (depth == 0) { + sb->map = NULL; + return 0; + } + + sb->map = kzalloc_node(sb->map_nr * sizeof(*sb->map), flags, node); + if (!sb->map) + return -ENOMEM; + + for (i = 0; i < sb->map_nr; i++) { + sb->map[i].depth = min(depth, bits_per_word); + depth -= sb->map[i].depth; + } + return 0; +} +EXPORT_SYMBOL_GPL(sbitmap_init_node); + +void sbitmap_resize(struct sbitmap *sb, unsigned int depth) +{ + unsigned int bits_per_word = 1U << sb->shift; + unsigned int i; + + sb->depth = depth; + sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word); + + for (i = 0; i < sb->map_nr; i++) { + sb->map[i].depth = min(depth, bits_per_word); + depth -= sb->map[i].depth; + } +} +EXPORT_SYMBOL_GPL(sbitmap_resize); + +static int __sbitmap_get_word(struct sbitmap_word *word, unsigned int hint, + bool wrap) +{ + unsigned int orig_hint = hint; + int nr; + + while (1) { + nr = find_next_zero_bit(&word->word, word->depth, hint); + if (unlikely(nr >= word->depth)) { + /* + * We started with an offset, and we didn't reset the + * offset to 0 in a failure case, so start from 0 to + * exhaust the map. + */ + if (orig_hint && hint && wrap) { + hint = orig_hint = 0; + continue; + } + return -1; + } + + if (!test_and_set_bit(nr, &word->word)) + break; + + hint = nr + 1; + if (hint >= word->depth - 1) + hint = 0; + } + + return nr; +} + +int sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint, bool round_robin) +{ + unsigned int i, index; + int nr = -1; + + index = SB_NR_TO_INDEX(sb, alloc_hint); + + for (i = 0; i < sb->map_nr; i++) { + nr = __sbitmap_get_word(&sb->map[index], + SB_NR_TO_BIT(sb, alloc_hint), + !round_robin); + if (nr != -1) { + nr += index << sb->shift; + break; + } + + /* Jump to next index. */ + index++; + alloc_hint = index << sb->shift; + + if (index >= sb->map_nr) { + index = 0; + alloc_hint = 0; + } + } + + return nr; +} +EXPORT_SYMBOL_GPL(sbitmap_get); + +bool sbitmap_any_bit_set(const struct sbitmap *sb) +{ + unsigned int i; + + for (i = 0; i < sb->map_nr; i++) { + if (sb->map[i].word) + return true; + } + return false; +} +EXPORT_SYMBOL_GPL(sbitmap_any_bit_set); + +bool sbitmap_any_bit_clear(const struct sbitmap *sb) +{ + unsigned int i; + + for (i = 0; i < sb->map_nr; i++) { + const struct sbitmap_word *word = &sb->map[i]; + unsigned long ret; + + ret = find_first_zero_bit(&word->word, word->depth); + if (ret < word->depth) + return true; + } + return false; +} +EXPORT_SYMBOL_GPL(sbitmap_any_bit_clear); + +unsigned int sbitmap_weight(const struct sbitmap *sb) +{ + unsigned int i, weight; + + for (i = 0; i < sb->map_nr; i++) { + const struct sbitmap_word *word = &sb->map[i]; + + weight += bitmap_weight(&word->word, word->depth); + } + return weight; +} +EXPORT_SYMBOL_GPL(sbitmap_weight); + +static unsigned int sbq_calc_wake_batch(unsigned int depth) +{ + unsigned int wake_batch; + + /* + * For each batch, we wake up one queue. We need to make sure that our + * batch size is small enough that the full depth of the bitmap is + * enough to wake up all of the queues. + */ + wake_batch = SBQ_WAKE_BATCH; + if (wake_batch > depth / SBQ_WAIT_QUEUES) + wake_batch = max(1U, depth / SBQ_WAIT_QUEUES); + + return wake_batch; +} + +int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth, + int shift, gfp_t flags, int node) +{ + int ret; + int i; + + ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node); + if (ret) + return ret; + + sbq->wake_batch = sbq_calc_wake_batch(depth); + atomic_set(&sbq->wake_index, 0); + + sbq->ws = kzalloc(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags); + if (!sbq->ws) { + sbitmap_free(&sbq->sb); + return -ENOMEM; + } + + for (i = 0; i < SBQ_WAIT_QUEUES; i++) { + init_waitqueue_head(&sbq->ws[i].wait); + atomic_set(&sbq->ws[i].wait_cnt, sbq->wake_batch); + } + return 0; +} +EXPORT_SYMBOL_GPL(sbitmap_queue_init_node); + +void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth) +{ + sbq->wake_batch = sbq_calc_wake_batch(depth); + sbitmap_resize(&sbq->sb, depth); +} +EXPORT_SYMBOL_GPL(sbitmap_queue_resize); + +static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq) +{ + int i, wake_index; + + wake_index = atomic_read(&sbq->wake_index); + for (i = 0; i < SBQ_WAIT_QUEUES; i++) { + struct sbq_wait_state *ws = &sbq->ws[wake_index]; + + if (waitqueue_active(&ws->wait)) { + int o = atomic_read(&sbq->wake_index); + + if (wake_index != o) + atomic_cmpxchg(&sbq->wake_index, o, wake_index); + return ws; + } + + wake_index = sbq_index_inc(wake_index); + } + + return NULL; +} + +static void sbq_wake_up(struct sbitmap_queue *sbq) +{ + struct sbq_wait_state *ws; + int wait_cnt; + + /* Ensure that the wait list checks occur after clear_bit(). */ + smp_mb(); + + ws = sbq_wake_ptr(sbq); + if (!ws) + return; + + wait_cnt = atomic_dec_return(&ws->wait_cnt); + if (unlikely(wait_cnt < 0)) + wait_cnt = atomic_inc_return(&ws->wait_cnt); + if (wait_cnt == 0) { + atomic_add(sbq->wake_batch, &ws->wait_cnt); + sbq_index_atomic_inc(&sbq->wake_index); + wake_up(&ws->wait); + } +} + +void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr) +{ + sbitmap_clear_bit(&sbq->sb, nr); + sbq_wake_up(sbq); +} +EXPORT_SYMBOL_GPL(sbitmap_queue_clear); + +void sbitmap_queue_wake_all(struct sbitmap_queue *sbq) +{ + int i, wake_index; + + /* + * Make sure all changes prior to this are visible from other CPUs. + */ + smp_mb(); + wake_index = atomic_read(&sbq->wake_index); + for (i = 0; i < SBQ_WAIT_QUEUES; i++) { + struct sbq_wait_state *ws = &sbq->ws[wake_index]; + + if (waitqueue_active(&ws->wait)) + wake_up(&ws->wait); + + wake_index = sbq_index_inc(wake_index); + } +} +EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all); |