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authorJens Axboe <axboe@fb.com>2014-05-19 11:52:35 -0600
committerJens Axboe <axboe@fb.com>2014-05-19 11:52:35 -0600
commit39a9f97e5ea99e048c4980c23cf197f6e77995cb (patch)
treeb1f72ed1e852372b6d86b79157b09f77fabc5a20 /block/blk-mq-tag.c
parent1429d7c9467e1e3de0b0ff91d7e4d67c1a92f8a3 (diff)
parent0d2602ca30e410e84e8bdf05c84ed5688e0a5a44 (diff)
downloadkernel-39a9f97e5ea99e048c4980c23cf197f6e77995cb.tar.gz
Merge branch 'for-3.16/blk-mq-tagging' into for-3.16/core
Signed-off-by: Jens Axboe <axboe@fb.com> Conflicts: block/blk-mq-tag.c
Diffstat (limited to 'block/blk-mq-tag.c')
-rw-r--r--block/blk-mq-tag.c112
1 files changed, 95 insertions, 17 deletions
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 03ce6a11ba79..e6b3fbae9862 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -7,13 +7,12 @@
#include "blk-mq.h"
#include "blk-mq-tag.h"
-void blk_mq_wait_for_tags(struct blk_mq_tags *tags, struct blk_mq_hw_ctx *hctx,
- bool reserved)
+void blk_mq_wait_for_tags(struct blk_mq_hw_ctx *hctx, bool reserved)
{
int tag, zero = 0;
- tag = blk_mq_get_tag(tags, hctx, &zero, __GFP_WAIT, reserved);
- blk_mq_put_tag(tags, tag, &zero);
+ tag = blk_mq_get_tag(hctx, &zero, __GFP_WAIT, reserved);
+ blk_mq_put_tag(hctx, tag, &zero);
}
static bool bt_has_free_tags(struct blk_mq_bitmap_tags *bt)
@@ -40,6 +39,84 @@ bool blk_mq_has_free_tags(struct blk_mq_tags *tags)
return bt_has_free_tags(&tags->bitmap_tags);
}
+static inline void bt_index_inc(unsigned int *index)
+{
+ *index = (*index + 1) & (BT_WAIT_QUEUES - 1);
+}
+
+/*
+ * If a previously inactive queue goes active, bump the active user count.
+ */
+bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx)
+{
+ if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) &&
+ !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
+ atomic_inc(&hctx->tags->active_queues);
+
+ return true;
+}
+
+/*
+ * If a previously busy queue goes inactive, potential waiters could now
+ * be allowed to queue. Wake them up and check.
+ */
+void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
+{
+ struct blk_mq_tags *tags = hctx->tags;
+ struct blk_mq_bitmap_tags *bt;
+ int i, wake_index;
+
+ if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
+ return;
+
+ atomic_dec(&tags->active_queues);
+
+ /*
+ * Will only throttle depth on non-reserved tags
+ */
+ bt = &tags->bitmap_tags;
+ 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))
+ wake_up(&bs->wait);
+
+ bt_index_inc(&wake_index);
+ }
+}
+
+/*
+ * For shared tag users, we track the number of currently active users
+ * 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)
+{
+ unsigned int depth, users;
+
+ if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_SHARED))
+ return true;
+ if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
+ return true;
+
+ /*
+ * Don't try dividing an ant
+ */
+ if (bt->depth == 1)
+ return true;
+
+ users = atomic_read(&hctx->tags->active_queues);
+ if (!users)
+ return true;
+
+ /*
+ * Allow at least some tags
+ */
+ depth = max((bt->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)
{
int tag, org_last_tag, end;
@@ -78,11 +155,15 @@ restart:
* 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)
+static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt,
+ unsigned int *tag_cache)
{
unsigned int last_tag, org_last_tag;
int index, i, tag;
+ if (!hctx_may_queue(hctx, bt))
+ return -1;
+
last_tag = org_last_tag = *tag_cache;
index = TAG_TO_INDEX(bt, last_tag);
@@ -117,11 +198,6 @@ done:
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)
{
@@ -142,7 +218,7 @@ static int bt_get(struct blk_mq_bitmap_tags *bt, struct blk_mq_hw_ctx *hctx,
DEFINE_WAIT(wait);
int tag;
- tag = __bt_get(bt, last_tag);
+ tag = __bt_get(hctx, bt, last_tag);
if (tag != -1)
return tag;
@@ -156,7 +232,7 @@ static int bt_get(struct blk_mq_bitmap_tags *bt, struct blk_mq_hw_ctx *hctx,
was_empty = list_empty(&wait.task_list);
prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE);
- tag = __bt_get(bt, last_tag);
+ tag = __bt_get(hctx, bt, last_tag);
if (tag != -1)
break;
@@ -200,14 +276,13 @@ static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_tags *tags,
return tag;
}
-unsigned int blk_mq_get_tag(struct blk_mq_tags *tags,
- struct blk_mq_hw_ctx *hctx, unsigned int *last_tag,
+unsigned int blk_mq_get_tag(struct blk_mq_hw_ctx *hctx, unsigned int *last_tag,
gfp_t gfp, bool reserved)
{
if (!reserved)
- return __blk_mq_get_tag(tags, hctx, last_tag, gfp);
+ return __blk_mq_get_tag(hctx->tags, hctx, last_tag, gfp);
- return __blk_mq_get_reserved_tag(tags, gfp);
+ return __blk_mq_get_reserved_tag(hctx->tags, gfp);
}
static struct bt_wait_state *bt_wake_ptr(struct blk_mq_bitmap_tags *bt)
@@ -265,9 +340,11 @@ static void __blk_mq_put_reserved_tag(struct blk_mq_tags *tags,
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_hw_ctx *hctx, unsigned int tag,
unsigned int *last_tag)
{
+ struct blk_mq_tags *tags = hctx->tags;
+
if (tag >= tags->nr_reserved_tags) {
const int real_tag = tag - tags->nr_reserved_tags;
@@ -465,6 +542,7 @@ ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page)
res = bt_unused_tags(&tags->breserved_tags);
page += sprintf(page, "nr_free=%u, nr_reserved=%u\n", free, res);
+ page += sprintf(page, "active_queues=%u\n", atomic_read(&tags->active_queues));
return page - orig_page;
}