Add a new queue flag QUEUE_FLAG_FAIR_TAG_SHARING to make the fair tag
sharing configurable.
Signed-off-by: Ed Tsai <ed.tsai@xxxxxxxxxxxx>
---
block/blk-mq-debugfs.c | 1 +
block/blk-mq-tag.c | 1 +
block/blk-mq.c | 3 ++-
include/linux/blkdev.h | 6 +++++-
4 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index d23a8554ec4a..f03b8bfe63be 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -103,6 +103,7 @@ static const char *const blk_queue_flag_name[] = {
QUEUE_FLAG_NAME(RQ_ALLOC_TIME),
QUEUE_FLAG_NAME(HCTX_ACTIVE),
QUEUE_FLAG_NAME(NOWAIT),
+ QUEUE_FLAG_NAME(FAIR_TAG_SHARING),
};
#undef QUEUE_FLAG_NAME
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index d6af9d431dc6..b8b36823f5f5 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -97,6 +97,7 @@ static int __blk_mq_get_tag(struct blk_mq_alloc_data *data,
struct sbitmap_queue *bt)
{
if (!data->q->elevator && !(data->flags & BLK_MQ_REQ_RESERVED) &&
+ blk_queue_fair_tag_sharing(data->q) &&
!hctx_may_queue(data->hctx, bt))
return BLK_MQ_NO_TAG;
diff --git a/block/blk-mq.c b/block/blk-mq.c
index f6dad0886a2f..f903107759f7 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1746,7 +1746,8 @@ static bool __blk_mq_alloc_driver_tag(struct request *rq)
bt = &rq->mq_hctx->tags->breserved_tags;
tag_offset = 0;
} else {
- if (!hctx_may_queue(rq->mq_hctx, bt))
+ if (blk_queue_fair_tag_sharing(rq->q) &&
+ !hctx_may_queue(rq->mq_hctx, bt))
return false;
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b441e633f4dd..7fcb2356860d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -561,10 +561,12 @@ struct request_queue {
#define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */
#define QUEUE_FLAG_SQ_SCHED 30 /* single queue style io dispatch */
#define QUEUE_FLAG_SKIP_TAGSET_QUIESCE 31 /* quiesce_tagset skip the queue*/
+#define QUEUE_FLAG_FAIR_TAG_SHARING 32 /* fair allocation of shared tags */
#define QUEUE_FLAG_MQ_DEFAULT ((1UL << QUEUE_FLAG_IO_STAT) | \
(1UL << QUEUE_FLAG_SAME_COMP) | \
- (1UL << QUEUE_FLAG_NOWAIT))
+ (1UL << QUEUE_FLAG_NOWAIT) | \
+ (1UL << QUEUE_FLAG_FAIR_TAG_SHARING))
void blk_queue_flag_set(unsigned int flag, struct request_queue *q);
void blk_queue_flag_clear(unsigned int flag, struct request_queue *q);
@@ -602,6 +604,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
#define blk_queue_sq_sched(q) test_bit(QUEUE_FLAG_SQ_SCHED, &(q)->queue_flags)
#define blk_queue_skip_tagset_quiesce(q) \
test_bit(QUEUE_FLAG_SKIP_TAGSET_QUIESCE, &(q)->queue_flags)
+#define blk_queue_fair_tag_sharing(q) \
+ test_bit(QUEUE_FLAG_FAIR_TAG_SHARING, &(q)->queue_flags)
extern void blk_set_pm_only(struct request_queue *q);
extern void blk_clear_pm_only(struct request_queue *q);
--
2.18.0
