When tag space of one device is big enough, we use hw tag
directly for I/O scheduling.
Now the decision is made if hw queue depth is not less than
q->nr_requests and the tag set isn't shared.
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
block/blk-mq-sched.c | 24 +++++++++++++++++-------
block/blk-mq-sched.h | 22 ++++++++++++++++++++++
block/blk-mq.c | 32 ++++++++++++++++++++++++++++++--
3 files changed, 69 insertions(+), 9 deletions(-)
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 817c97c88942..e25a2837d9f0 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -416,9 +416,9 @@ void blk_mq_sched_insert_requests(struct request_queue *q,
blk_mq_run_hw_queue(hctx, run_queue_async);
}
-static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
- struct blk_mq_hw_ctx *hctx,
- unsigned int hctx_idx)
+void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
+ struct blk_mq_hw_ctx *hctx,
+ unsigned int hctx_idx)
{
if (hctx->sched_tags) {
blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
@@ -427,9 +427,9 @@ static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
}
}
-static int blk_mq_sched_alloc_tags(struct request_queue *q,
- struct blk_mq_hw_ctx *hctx,
- unsigned int hctx_idx)
+int blk_mq_sched_alloc_tags(struct request_queue *q,
+ struct blk_mq_hw_ctx *hctx,
+ unsigned int hctx_idx)
{
struct blk_mq_tag_set *set = q->tag_set;
int ret;
@@ -455,8 +455,10 @@ static void blk_mq_sched_tags_teardown(struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
int i;
- queue_for_each_hw_ctx(q, hctx, i)
+ queue_for_each_hw_ctx(q, hctx, i) {
+ hctx->flags &= ~BLK_MQ_F_SCHED_USE_HW_TAG;
blk_mq_sched_free_tags(set, hctx, i);
+ }
}
int blk_mq_sched_init_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
@@ -505,6 +507,7 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
struct elevator_queue *eq;
unsigned int i;
int ret;
+ bool auto_hw_tag;
if (!e) {
q->elevator = NULL;
@@ -517,7 +520,14 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
*/
q->nr_requests = 2 * BLKDEV_MAX_RQ;
+ auto_hw_tag = blk_mq_sched_may_use_hw_tag(q);
+
queue_for_each_hw_ctx(q, hctx, i) {
+ if (auto_hw_tag)
+ hctx->flags |= BLK_MQ_F_SCHED_USE_HW_TAG;
+ else
+ hctx->flags &= ~BLK_MQ_F_SCHED_USE_HW_TAG;
+
ret = blk_mq_sched_alloc_tags(q, hctx, i);
if (ret)
goto err;
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index edafb5383b7b..241d23c18181 100644
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -35,6 +35,13 @@ void blk_mq_sched_exit_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
int blk_mq_sched_init(struct request_queue *q);
+void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
+ struct blk_mq_hw_ctx *hctx,
+ unsigned int hctx_idx);
+int blk_mq_sched_alloc_tags(struct request_queue *q,
+ struct blk_mq_hw_ctx *hctx,
+ unsigned int hctx_idx);
+
static inline bool
blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
{
@@ -129,4 +136,19 @@ static inline bool blk_mq_sched_needs_restart(struct blk_mq_hw_ctx *hctx)
return test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
}
+/*
+ * If this queue has enough hardware tags and doesn't share tags with
+ * other queues, just use hw tag directly for scheduling.
+ */
+static inline bool blk_mq_sched_may_use_hw_tag(struct request_queue *q)
+{
+ if (q->tag_set->flags & BLK_MQ_F_TAG_SHARED)
+ return false;
+
+ if (blk_mq_get_queue_depth(q) < q->nr_requests)
+ return false;
+
+ return true;
+}
+
#endif
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 681bf33d8de8..0d9433680b2a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2132,6 +2132,31 @@ int blk_mq_get_queue_depth(struct request_queue *q)
return tags->bitmap_tags.sb.depth + tags->breserved_tags.sb.depth;
}
+static void blk_mq_update_sched_flag(struct request_queue *q)
+{
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ if (!q->elevator)
+ return;
+
+ if (!blk_mq_sched_may_use_hw_tag(q))
+ queue_for_each_hw_ctx(q, hctx, i) {
+ hctx->flags &= ~BLK_MQ_F_SCHED_USE_HW_TAG;
+ if (!hctx->sched_tags) {
+ if (blk_mq_sched_alloc_tags(q, hctx, i))
+ goto force_use_hw_tag;
+ }
+ }
+ else
+ force_use_hw_tag:
+ queue_for_each_hw_ctx(q, hctx, i) {
+ hctx->flags |= BLK_MQ_F_SCHED_USE_HW_TAG;
+ if (hctx->sched_tags)
+ blk_mq_sched_free_tags(q->tag_set, hctx, i);
+ }
+}
+
static void queue_set_hctx_shared(struct request_queue *q, bool shared)
{
struct blk_mq_hw_ctx *hctx;
@@ -2671,8 +2696,11 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
break;
}
- if (!ret && sched)
- q->nr_requests = nr;
+ if (!ret) {
+ if (sched)
+ q->nr_requests = nr;
+ blk_mq_update_sched_flag(q);
+ }
blk_mq_unfreeze_queue(q);
--
2.9.3
