#include <linux/kernel.h>
#include <linux/module.h>
+#include <linux/random.h>
#include <linux/blk-mq.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-tag.h"
-void blk_mq_wait_for_tags(struct blk_mq_tags *tags, bool reserved)
+void blk_mq_wait_for_tags(struct blk_mq_tags *tags, struct blk_mq_hw_ctx *hctx,
+ bool reserved)
{
- int tag = blk_mq_get_tag(tags, __GFP_WAIT, reserved);
- blk_mq_put_tag(tags, tag);
+ int tag, zero = 0;
+
+ tag = blk_mq_get_tag(tags, hctx, &zero, __GFP_WAIT, reserved);
+ blk_mq_put_tag(tags, tag, &zero);
+}
+
+static bool bt_has_free_tags(struct blk_mq_bitmap_tags *bt)
+{
+ int i;
+
+ for (i = 0; i < bt->map_nr; i++) {
+ struct blk_mq_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)
{
- return !tags ||
- percpu_ida_free_tags(&tags->free_tags, nr_cpu_ids) != 0;
+ if (!tags)
+ return true;
+
+ return bt_has_free_tags(&tags->bitmap_tags);
+}
+
+static int __bt_get_word(struct blk_mq_bitmap *bm, unsigned int last_tag)
+{
+ int tag, org_last_tag, end;
+
+ org_last_tag = last_tag = TAG_TO_BIT(last_tag);
+ end = bm->depth;
+ do {
+restart:
+ tag = find_next_zero_bit(&bm->word, end, last_tag);
+ if (unlikely(tag >= end)) {
+ /*
+ * We started with an offset, start from 0 to
+ * exhaust the map.
+ */
+ if (org_last_tag && last_tag) {
+ end = last_tag;
+ last_tag = 0;
+ goto restart;
+ }
+ return -1;
+ }
+ last_tag = tag + 1;
+ } while (test_and_set_bit_lock(tag, &bm->word));
+
+ return tag;
+}
+
+/*
+ * 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_bitmap_tags *bt, unsigned int *tag_cache)
+{
+ unsigned int last_tag, org_last_tag;
+ int index, i, tag;
+
+ last_tag = org_last_tag = *tag_cache;
+ index = TAG_TO_INDEX(last_tag);
+
+ for (i = 0; i < bt->map_nr; i++) {
+ tag = __bt_get_word(&bt->map[index], last_tag);
+ if (tag != -1) {
+ tag += index * BITS_PER_LONG;
+ goto done;
+ }
+
+ last_tag = 0;
+ if (++index >= bt->map_nr)
+ index = 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) {
+ last_tag = tag + 1;
+ if (last_tag >= bt->depth - 1)
+ last_tag = 0;
+
+ *tag_cache = last_tag;
+ }
+
+ return tag;
+}
+
+static inline void bt_index_inc(unsigned int *index)
+{
+ *index = (*index + 1) & (BT_WAIT_QUEUES - 1);
+}
+
+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;
+
+ if (!hctx)
+ return &bt->bs[0];
+
+ bs = &bt->bs[hctx->wait_index];
+ bt_index_inc(&hctx->wait_index);
+ return bs;
}
-static unsigned int __blk_mq_get_tag(struct blk_mq_tags *tags, gfp_t gfp)
+static int bt_get(struct blk_mq_bitmap_tags *bt, struct blk_mq_hw_ctx *hctx,
+ unsigned int *last_tag, gfp_t gfp)
{
+ struct bt_wait_state *bs;
+ DEFINE_WAIT(wait);
int tag;
- tag = percpu_ida_alloc(&tags->free_tags, (gfp & __GFP_WAIT) ?
- TASK_UNINTERRUPTIBLE : TASK_RUNNING);
- if (tag < 0)
- return BLK_MQ_TAG_FAIL;
- return tag + tags->nr_reserved_tags;
+ tag = __bt_get(bt, last_tag);
+ if (tag != -1)
+ return tag;
+
+ if (!(gfp & __GFP_WAIT))
+ return -1;
+
+ bs = bt_wait_ptr(bt, hctx);
+ do {
+ bool was_empty;
+
+ was_empty = list_empty(&wait.task_list);
+ prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE);
+
+ tag = __bt_get(bt, last_tag);
+ if (tag != -1)
+ break;
+
+ if (was_empty)
+ atomic_set(&bs->wait_cnt, bt->wake_cnt);
+
+ io_schedule();
+ } while (1);
+
+ finish_wait(&bs->wait, &wait);
+ return tag;
+}
+
+static unsigned int __blk_mq_get_tag(struct blk_mq_tags *tags,
+ struct blk_mq_hw_ctx *hctx,
+ unsigned int *last_tag, gfp_t gfp)
+{
+ int tag;
+
+ tag = bt_get(&tags->bitmap_tags, hctx, last_tag, gfp);
+ if (tag >= 0)
+ return tag + tags->nr_reserved_tags;
+
+ return BLK_MQ_TAG_FAIL;
}
static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_tags *tags,
gfp_t gfp)
{
- int tag;
+ int tag, zero = 0;
if (unlikely(!tags->nr_reserved_tags)) {
WARN_ON_ONCE(1);
return BLK_MQ_TAG_FAIL;
}
- tag = percpu_ida_alloc(&tags->reserved_tags, (gfp & __GFP_WAIT) ?
- TASK_UNINTERRUPTIBLE : TASK_RUNNING);
+ tag = bt_get(&tags->breserved_tags, NULL, &zero, gfp);
if (tag < 0)
return BLK_MQ_TAG_FAIL;
+
return tag;
}
-unsigned int blk_mq_get_tag(struct blk_mq_tags *tags, gfp_t gfp, bool reserved)
+unsigned int blk_mq_get_tag(struct blk_mq_tags *tags,
+ struct blk_mq_hw_ctx *hctx, unsigned int *last_tag,
+ gfp_t gfp, bool reserved)
{
if (!reserved)
- return __blk_mq_get_tag(tags, gfp);
+ return __blk_mq_get_tag(tags, hctx, last_tag, gfp);
return __blk_mq_get_reserved_tag(tags, gfp);
}
+static struct bt_wait_state *bt_wake_ptr(struct blk_mq_bitmap_tags *bt)
+{
+ int i, wake_index;
+
+ wake_index = 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)) {
+ if (wake_index != bt->wake_index)
+ bt->wake_index = wake_index;
+
+ return bs;
+ }
+
+ 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(tag);
+ struct bt_wait_state *bs;
+
+ clear_bit(TAG_TO_BIT(tag), &bt->map[index].word);
+
+ bs = bt_wake_ptr(bt);
+ if (bs && atomic_dec_and_test(&bs->wait_cnt)) {
+ smp_mb__after_clear_bit();
+ atomic_set(&bs->wait_cnt, bt->wake_cnt);
+ bt_index_inc(&bt->wake_index);
+ wake_up(&bs->wait);
+ }
+}
+
static void __blk_mq_put_tag(struct blk_mq_tags *tags, unsigned int tag)
{
BUG_ON(tag >= tags->nr_tags);
- percpu_ida_free(&tags->free_tags, tag - tags->nr_reserved_tags);
+ bt_clear_tag(&tags->bitmap_tags, tag);
}
static void __blk_mq_put_reserved_tag(struct blk_mq_tags *tags,
{
BUG_ON(tag >= tags->nr_reserved_tags);
- percpu_ida_free(&tags->reserved_tags, tag);
+ bt_clear_tag(&tags->breserved_tags, tag);
}
-void blk_mq_put_tag(struct blk_mq_tags *tags, unsigned int tag)
+void blk_mq_put_tag(struct blk_mq_tags *tags, unsigned int tag,
+ unsigned int *last_tag)
{
- if (tag >= tags->nr_reserved_tags)
- __blk_mq_put_tag(tags, tag);
- else
+ if (tag >= tags->nr_reserved_tags) {
+ const int real_tag = tag - tags->nr_reserved_tags;
+
+ __blk_mq_put_tag(tags, real_tag);
+ *last_tag = real_tag;
+ } else
__blk_mq_put_reserved_tag(tags, tag);
}
-static int __blk_mq_tag_iter(unsigned id, void *data)
+static void bt_for_each_free(struct blk_mq_bitmap_tags *bt,
+ unsigned long *free_map, unsigned int off)
{
- unsigned long *tag_map = data;
- __set_bit(id, tag_map);
- return 0;
+ int i;
+
+ for (i = 0; i < bt->map_nr; i++) {
+ struct blk_mq_bitmap *bm = &bt->map[i];
+ int bit = 0;
+
+ do {
+ bit = find_next_zero_bit(&bm->word, bm->depth, bit);
+ if (bit >= bm->depth)
+ break;
+
+ __set_bit(bit + off, free_map);
+ bit++;
+ } while (1);
+
+ off += BITS_PER_LONG;
+ }
}
void blk_mq_tag_busy_iter(struct blk_mq_tags *tags,
if (!tag_map)
return;
- percpu_ida_for_each_free(&tags->free_tags, __blk_mq_tag_iter, tag_map);
+ bt_for_each_free(&tags->bitmap_tags, tag_map, tags->nr_reserved_tags);
if (tags->nr_reserved_tags)
- percpu_ida_for_each_free(&tags->reserved_tags, __blk_mq_tag_iter,
- tag_map);
+ bt_for_each_free(&tags->breserved_tags, tag_map, 0);
fn(data, tag_map);
kfree(tag_map);
}
+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_mq_bitmap *bm = &bt->map[i];
+
+ used += bitmap_weight(&bm->word, bm->depth);
+ }
+
+ return bt->depth - used;
+}
+
+static int bt_alloc(struct blk_mq_bitmap_tags *bt, unsigned int depth,
+ int node, bool reserved)
+{
+ int i;
+
+ /*
+ * Depth can be zero for reserved tags, that's not a failure
+ * condition.
+ */
+ if (depth) {
+ int nr, i, map_depth;
+
+ nr = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG;
+ bt->map = kzalloc_node(nr * sizeof(struct blk_mq_bitmap),
+ GFP_KERNEL, node);
+ if (!bt->map)
+ return -ENOMEM;
+
+ bt->map_nr = nr;
+ map_depth = depth;
+ for (i = 0; i < nr; i++) {
+ bt->map[i].depth = min(map_depth, BITS_PER_LONG);
+ map_depth -= BITS_PER_LONG;
+ }
+ }
+
+ bt->bs = kzalloc(BT_WAIT_QUEUES * sizeof(*bt->bs), GFP_KERNEL);
+ if (!bt->bs) {
+ kfree(bt->map);
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < BT_WAIT_QUEUES; i++)
+ init_waitqueue_head(&bt->bs[i].wait);
+
+ bt->wake_cnt = BT_WAIT_BATCH;
+ if (bt->wake_cnt > depth / 4)
+ bt->wake_cnt = max(1U, depth / 4);
+
+ bt->depth = depth;
+ return 0;
+}
+
+static void bt_free(struct blk_mq_bitmap_tags *bt)
+{
+ kfree(bt->map);
+ kfree(bt->bs);
+}
+
+static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags,
+ int node)
+{
+ unsigned int depth = tags->nr_tags - tags->nr_reserved_tags;
+
+ 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;
+
+ return tags;
+enomem:
+ bt_free(&tags->bitmap_tags);
+ kfree(tags);
+ return NULL;
+}
+
struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
unsigned int reserved_tags, int node)
{
unsigned int nr_tags, nr_cache;
struct blk_mq_tags *tags;
- int ret;
if (total_tags > BLK_MQ_TAG_MAX) {
pr_err("blk-mq: tag depth too large\n");
return NULL;
nr_tags = total_tags - reserved_tags;
- nr_cache = nr_tags / num_possible_cpus();
-
- if (nr_cache < BLK_MQ_TAG_CACHE_MIN)
- nr_cache = BLK_MQ_TAG_CACHE_MIN;
- else if (nr_cache > BLK_MQ_TAG_CACHE_MAX)
- nr_cache = BLK_MQ_TAG_CACHE_MAX;
+ nr_cache = nr_tags / num_online_cpus();
tags->nr_tags = total_tags;
tags->nr_reserved_tags = reserved_tags;
- tags->nr_max_cache = nr_cache;
- tags->nr_batch_move = max(1u, nr_cache / 2);
-
- ret = __percpu_ida_init(&tags->free_tags, tags->nr_tags -
- tags->nr_reserved_tags,
- tags->nr_max_cache,
- tags->nr_batch_move);
- if (ret)
- goto err_free_tags;
-
- if (reserved_tags) {
- /*
- * With max_cahe and batch set to 1, the allocator fallbacks to
- * no cached. It's fine reserved tags allocation is slow.
- */
- ret = __percpu_ida_init(&tags->reserved_tags, reserved_tags,
- 1, 1);
- if (ret)
- goto err_reserved_tags;
- }
- return tags;
-
-err_reserved_tags:
- percpu_ida_destroy(&tags->free_tags);
-err_free_tags:
- kfree(tags);
- return NULL;
+ return blk_mq_init_bitmap_tags(tags, node);
}
void blk_mq_free_tags(struct blk_mq_tags *tags)
{
- percpu_ida_destroy(&tags->free_tags);
- percpu_ida_destroy(&tags->reserved_tags);
+ bt_free(&tags->bitmap_tags);
+ bt_free(&tags->breserved_tags);
kfree(tags);
}
+void blk_mq_tag_init_last_tag(struct blk_mq_tags *tags, unsigned int *tag)
+{
+ unsigned int depth = tags->nr_tags - tags->nr_reserved_tags;
+
+ if (depth > 1)
+ *tag = prandom_u32() % (depth - 1);
+ else
+ *tag = 0;
+}
+
ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page)
{
char *orig_page = page;
- unsigned int cpu;
+ unsigned int free, res;
if (!tags)
return 0;
- page += sprintf(page, "nr_tags=%u, reserved_tags=%u, batch_move=%u,"
- " max_cache=%u\n", tags->nr_tags, tags->nr_reserved_tags,
- tags->nr_batch_move, tags->nr_max_cache);
+ page += sprintf(page, "nr_tags=%u, reserved_tags=%u\n",
+ tags->nr_tags, tags->nr_reserved_tags);
- page += sprintf(page, "nr_free=%u, nr_reserved=%u\n",
- percpu_ida_free_tags(&tags->free_tags, nr_cpu_ids),
- percpu_ida_free_tags(&tags->reserved_tags, nr_cpu_ids));
+ free = bt_unused_tags(&tags->bitmap_tags);
+ res = bt_unused_tags(&tags->breserved_tags);
- for_each_possible_cpu(cpu) {
- page += sprintf(page, " cpu%02u: nr_free=%u\n", cpu,
- percpu_ida_free_tags(&tags->free_tags, cpu));
- }
+ page += sprintf(page, "nr_free=%u, nr_reserved=%u\n", free, res);
return page - orig_page;
}
}
static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
+ struct blk_mq_ctx *ctx,
gfp_t gfp, bool reserved)
{
struct request *rq;
unsigned int tag;
- tag = blk_mq_get_tag(hctx->tags, gfp, reserved);
+ tag = blk_mq_get_tag(hctx->tags, hctx, &ctx->last_tag, gfp, reserved);
if (tag != BLK_MQ_TAG_FAIL) {
rq = hctx->tags->rqs[tag];
rq->tag = tag;
struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
- rq = __blk_mq_alloc_request(hctx, gfp & ~__GFP_WAIT, reserved);
+ rq = __blk_mq_alloc_request(hctx, ctx, gfp & ~__GFP_WAIT,
+ reserved);
if (rq) {
blk_mq_rq_ctx_init(q, ctx, rq, rw);
break;
break;
}
- blk_mq_wait_for_tags(hctx->tags, reserved);
+ blk_mq_wait_for_tags(hctx->tags, hctx, reserved);
} while (1);
return rq;
blk_mq_put_ctx(rq->mq_ctx);
return rq;
}
+EXPORT_SYMBOL(blk_mq_alloc_request);
struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
gfp_t gfp)
struct request_queue *q = rq->q;
clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
- blk_mq_put_tag(hctx->tags, tag);
+ blk_mq_put_tag(hctx->tags, tag, &ctx->last_tag);
blk_mq_queue_exit(q);
}
queued++;
continue;
case BLK_MQ_RQ_QUEUE_BUSY:
- /*
- * FIXME: we should have a mechanism to stop the queue
- * like blk_stop_queue, otherwise we will waste cpu
- * time
- */
list_add(&rq->queuelist, &rq_list);
__blk_mq_requeue_request(rq);
break;
list_add(&rq->queuelist, &ctx->rq_list);
else
list_add_tail(&rq->queuelist, &ctx->rq_list);
+
blk_mq_hctx_mark_pending(hctx, ctx);
/*
if (is_sync)
rw |= REQ_SYNC;
trace_block_getrq(q, bio, rw);
- rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false);
+ rq = __blk_mq_alloc_request(hctx, ctx, GFP_ATOMIC, false);
if (likely(rq))
blk_mq_rq_ctx_init(q, ctx, rq, rw);
else {
struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_tag_set *set,
unsigned int hctx_index)
{
- return kmalloc_node(sizeof(struct blk_mq_hw_ctx),
- GFP_KERNEL | __GFP_ZERO, set->numa_node);
+ return kzalloc_node(sizeof(struct blk_mq_hw_ctx), GFP_KERNEL,
+ set->numa_node);
}
EXPORT_SYMBOL(blk_mq_alloc_single_hw_queue);
projects / GitHub / exynos8895 / android_kernel_samsung_universal8895.git / commitdiff