linux-kernel - [PATCH BUGFIX IMPROVEMENT 4/7] block, bfq: bring forward seek&think time update

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Date:   Mon, 24 Jun 2019 21:40:39 +0200
From:   Paolo Valente <paolo.valente@...aro.org>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        ulf.hansson@...aro.org, linus.walleij@...aro.org,
        bfq-iosched@...glegroups.com, oleksandr@...alenko.name,
        bottura.nicola95@...il.com, srivatsa@...il.mit.edu,
        Paolo Valente <paolo.valente@...aro.org>
Subject: [PATCH BUGFIX IMPROVEMENT 4/7] block, bfq: bring forward seek&think time update

Until the base value for request service times gets finally computed
for a bfq_queue, the inject limit for that queue does depend on the
think-time state (short|long) of the queue. A timely update of the
think time then guarantees a quicker activation or deactivation of the
injection. Fortunately, the think time of a bfq_queue is updated in
the same code path as the inject limit; but after the inject limit.

This commits moves the update of the think time before the update of
the inject limit. For coherence, it moves the update of the seek time
too.

Tested-by: Srivatsa S. Bhat <srivatsa@...il.mit.edu>
Signed-off-by: Paolo Valente <paolo.valente@...aro.org>
---
 block/bfq-iosched.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 62442083b147..d5bc32371ace 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -4979,19 +4979,9 @@ static void bfq_update_has_short_ttime(struct bfq_data *bfqd,
 static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 			    struct request *rq)
 {
-	struct bfq_io_cq *bic = RQ_BIC(rq);
-
 	if (rq->cmd_flags & REQ_META)
 		bfqq->meta_pending++;
 
-	bfq_update_io_thinktime(bfqd, bfqq);
-	bfq_update_has_short_ttime(bfqd, bfqq, bic);
-	bfq_update_io_seektime(bfqd, bfqq, rq);
-
-	bfq_log_bfqq(bfqd, bfqq,
-		     "rq_enqueued: has_short_ttime=%d (seeky %d)",
-		     bfq_bfqq_has_short_ttime(bfqq), BFQQ_SEEKY(bfqq));
-
 	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
 
 	if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) {
@@ -5079,6 +5069,10 @@ static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
 		bfqq = new_bfqq;
 	}
 
+	bfq_update_io_thinktime(bfqd, bfqq);
+	bfq_update_has_short_ttime(bfqd, bfqq, RQ_BIC(rq));
+	bfq_update_io_seektime(bfqd, bfqq, rq);
+
 	waiting = bfqq && bfq_bfqq_wait_request(bfqq);
 	bfq_add_request(rq);
 	idle_timer_disabled = waiting && !bfq_bfqq_wait_request(bfqq);
-- 
2.20.1