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From: Paolo Valente <paolo.valente@linaro.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	mariottiluca1@hotmail.it, holger@applied-asynchrony.com,
	pedroni.pietro.96@gmail.com,
	Paolo Valente <paolo.valente@unimore.it>
Subject: [PATCH FIXES/IMPROVEMENTS 2/7] block, bfq: fix delayed stable merge check
Date: Sat, 19 Jun 2021 16:09:43 +0200	[thread overview]
Message-ID: <20210619140948.98712-3-paolo.valente@linaro.org> (raw)
In-Reply-To: <20210619140948.98712-1-paolo.valente@linaro.org>

From: Luca Mariotti <mariottiluca1@hotmail.it>

When attempting to schedule a merge of a given bfq_queue with the currently
in-service bfq_queue or with a cooperating bfq_queue among the scheduled
bfq_queues, delayed stable merge is checked for rotational or non-queueing
devs. For this stable merge to be performed, some conditions must be met.
If the current bfq_queue underwent some split from some merged bfq_queue,
one of these conditions is that two hundred milliseconds must elapse from
split, otherwise this condition is always met.

Unfortunately, by mistake, time_is_after_jiffies() was written instead of
time_is_before_jiffies() for this check, verifying that less than two
hundred milliseconds have elapsed instead of verifying that at least two
hundred milliseconds have elapsed.

Fix this issue by replacing time_is_after_jiffies() with
time_is_before_jiffies().

Signed-off-by: Luca Mariotti <mariottiluca1@hotmail.it>
Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Pietro Pedroni <pedroni.pietro.96@gmail.com>
---
 block/bfq-iosched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index da2363f12e53..c5c0e74977d4 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2710,7 +2710,7 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 	if (unlikely(!bfqd->nonrot_with_queueing)) {
 		if (bic->stable_merge_bfqq &&
 		    !bfq_bfqq_just_created(bfqq) &&
-		    time_is_after_jiffies(bfqq->split_time +
+		    time_is_before_jiffies(bfqq->split_time +
 					  msecs_to_jiffies(200))) {
 			struct bfq_queue *stable_merge_bfqq =
 				bic->stable_merge_bfqq;
-- 
2.20.1


  parent reply	other threads:[~2021-06-19 14:10 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-19 14:09 [PATCH FIXES/IMPROVEMENTS 0/7] block, bfq: preserve control, boost throughput, fix bugs Paolo Valente
2021-06-19 14:09 ` [PATCH FIXES/IMPROVEMENTS 1/7] block, bfq: let also stably merged queues enjoy weight raising Paolo Valente
2021-06-19 14:09 ` Paolo Valente [this message]
2021-06-19 14:09 ` [PATCH FIXES/IMPROVEMENTS 3/7] block, bfq: consider also creation time in delayed stable merge Paolo Valente
2021-06-19 14:09 ` [PATCH FIXES/IMPROVEMENTS 4/7] block, bfq: boost throughput by extending queue-merging times Paolo Valente
2021-06-19 14:09 ` [PATCH FIXES/IMPROVEMENTS 5/7] block, bfq: avoid delayed merge of async queues Paolo Valente
2021-06-19 14:09 ` [PATCH FIXES/IMPROVEMENTS 6/7] block, bfq: check waker only for queues with no in-flight I/O Paolo Valente
2021-06-19 14:09 ` [PATCH FIXES/IMPROVEMENTS 7/7] block, bfq: reset waker pointer with shared queues Paolo Valente
2021-06-21 16:08 ` [PATCH FIXES/IMPROVEMENTS 0/7] block, bfq: preserve control, boost throughput, fix bugs Jens Axboe
2021-06-21 19:55 ` Oleksandr Natalenko
2021-06-21 20:03   ` Piotr Górski
2021-06-22  7:08   ` Paolo Valente
2021-06-22  7:35     ` Oleksandr Natalenko
2021-06-22 16:29       ` Jan Kara
2021-06-22 17:26         ` Oleksandr Natalenko
2021-07-02 22:07         ` Oleksandr Natalenko
2021-08-02 20:40           ` Oleksandr Natalenko
2021-08-03 10:45             ` Jan Kara

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