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[v1] block: make the fair sharing of tag configurable

Message ID 20230509012758.27094-1-ed.tsai@mediatek.com
State New
Headers show
Series [v1] block: make the fair sharing of tag configurable | expand

Commit Message

Ed Tsai (蔡宗軒) May 9, 2023, 1:27 a.m. UTC 
The tags allocation is limited by the fair sharing algorithm. It hurts
the performance for UFS devices, because the queue depth of general I/O
is reduced by half once the UFS send a control command.

Add a new queue flag QUEUE_FLAG_FAIR_TAG_SHARING to make the fair tag
sharing configurable.

See also https://lore.kernel.org/all/20230103195337.158625-1-bvanassche@acm.org

Signed-off-by: Ed Tsai <ed.tsai@mediatek.com>
---
 block/blk-mq-debugfs.c    | 1 +
 block/blk-mq-tag.c        | 1 +
 block/blk-mq.c            | 3 ++-
 drivers/ufs/core/ufshcd.c | 3 +++
 include/linux/blkdev.h    | 6 +++++-
 5 files changed, 12 insertions(+), 2 deletions(-)

Comments

Bart Van Assche May 9, 2023, 4:22 a.m. UTC | #1 
On 5/8/23 18:27, Ed Tsai wrote:
> 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;

Has it been considered to move the blk_queue_fair_tag_sharing() call into
hctx_may_queue()? That should make this patch shorter.

> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 17d7bb875fee..e96a50265285 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -5149,6 +5149,9 @@ static int ufshcd_slave_configure(struct scsi_device *sdev)
>   	blk_queue_update_dma_pad(q, PRDT_DATA_BYTE_COUNT_PAD - 1);
>   	if (hba->quirks & UFSHCD_QUIRK_4KB_DMA_ALIGNMENT)
>   		blk_queue_update_dma_alignment(q, 4096 - 1);
> +
> +	blk_queue_flag_clear(QUEUE_FLAG_FAIR_TAG_SHARING, q);
> +
>   	/*
>   	 * Block runtime-pm until all consumers are added.
>   	 * Refer ufshcd_setup_links().

Please split this patch into one patch for the block layer core and another
patch for the UFS driver.

Thanks,

Bart.
diff mbox series

Patch

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..41f7e2b500bd 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/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 17d7bb875fee..e96a50265285 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -5149,6 +5149,9 @@  static int ufshcd_slave_configure(struct scsi_device *sdev)
 	blk_queue_update_dma_pad(q, PRDT_DATA_BYTE_COUNT_PAD - 1);
 	if (hba->quirks & UFSHCD_QUIRK_4KB_DMA_ALIGNMENT)
 		blk_queue_update_dma_alignment(q, 4096 - 1);
+
+	blk_queue_flag_clear(QUEUE_FLAG_FAIR_TAG_SHARING, q);
+
 	/*
 	 * Block runtime-pm until all consumers are added.
 	 * Refer ufshcd_setup_links().
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);