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Commit b3c34981 authored by Paolo Valente's avatar Paolo Valente Committed by Jens Axboe
Browse files

block, bfq: port commit "cfq-iosched: improve hw_tag detection" 



The original commit is commit 1a1238a7 ("cfq-iosched: improve hw_tag
detection") and has the following commit message:

If active queue hasn't enough requests and idle window opens, cfq will
not dispatch sufficient requests to hardware. In such situation, current
code will zero hw_tag. But this is because cfq doesn't dispatch enough
requests instead of hardware queue doesn't work. Don't zero hw_tag in
such case.

Signed-off-by: default avatarPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent a3c92560

block/bfq-iosched.c

+13 −0
Original line number Diff line number Diff line
@@ -4786,6 +4786,8 @@ static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx, 


static void bfq_update_hw_tag(struct bfq_data *bfqd)

{

	struct bfq_queue *bfqq = bfqd->in_service_queue;



	bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver,

				       bfqd->rq_in_driver);
@@ -4801,6 +4803,17 @@ static void bfq_update_hw_tag(struct bfq_data *bfqd) 
	if (bfqd->rq_in_driver + bfqd->queued <= BFQ_HW_QUEUE_THRESHOLD)

		return;



	/*

	 * If active queue hasn't enough requests and can idle, bfq might not

	 * dispatch sufficient requests to hardware. Don't zero hw_tag in this

	 * case

	 */

	if (bfqq && bfq_bfqq_has_short_ttime(bfqq) &&

	    bfqq->dispatched + bfqq->queued[0] + bfqq->queued[1] <

	    BFQ_HW_QUEUE_THRESHOLD &&

	    bfqd->rq_in_driver < BFQ_HW_QUEUE_THRESHOLD)

		return;



	if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)

		return;