From: Paolo Valente <paolo.valente@linaro.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
Paolo Valente <paolo.valente@linaro.org>, Jan Kara <jack@suse.cz>
Subject: [PATCH BUGFIX/IMPROVEMENT V2 4/6] block, bfq: fix weight-raising resume with !low_latency
Date: Thu, 4 Mar 2021 18:46:25 +0100 [thread overview]
Message-ID: <20210304174627.161-5-paolo.valente@linaro.org> (raw)
In-Reply-To: <20210304174627.161-1-paolo.valente@linaro.org>
When the io_latency heuristic is off, bfq_queues must not start to be
weight-raised. Unfortunately, by mistake, this may happen when the
state of a previously weight-raised bfq_queue is resumed after a queue
split. This commit fixes this error.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
block/bfq-iosched.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 4b3d4849f3f5..8497d0803d74 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -1010,7 +1010,7 @@ static void
bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
struct bfq_io_cq *bic, bool bfq_already_existing)
{
- unsigned int old_wr_coeff = bfqq->wr_coeff;
+ unsigned int old_wr_coeff = 1;
bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq);
if (bic->saved_has_short_ttime)
@@ -1031,7 +1031,13 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
bfqq->ttime = bic->saved_ttime;
bfqq->io_start_time = bic->saved_io_start_time;
bfqq->tot_idle_time = bic->saved_tot_idle_time;
- bfqq->wr_coeff = bic->saved_wr_coeff;
+ /*
+ * Restore weight coefficient only if low_latency is on
+ */
+ if (bfqd->low_latency) {
+ old_wr_coeff = bfqq->wr_coeff;
+ bfqq->wr_coeff = bic->saved_wr_coeff;
+ }
bfqq->service_from_wr = bic->saved_service_from_wr;
bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt;
bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish;
--
2.20.1
next prev parent reply other threads:[~2021-03-04 17:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-04 17:46 [PATCH BUGFIX/IMPROVEMENT V2 0/6] revised version of third and last batch of patches Paolo Valente
2021-03-04 17:46 ` [PATCH BUGFIX/IMPROVEMENT V2 1/6] block, bfq: always inject I/O of queues blocked by wakers Paolo Valente
2021-03-04 17:46 ` [PATCH BUGFIX/IMPROVEMENT V2 2/6] block, bfq: put reqs of waker and woken in dispatch list Paolo Valente
2021-03-04 17:46 ` [PATCH BUGFIX/IMPROVEMENT V2 3/6] block, bfq: make shared queues inherit wakers Paolo Valente
2021-03-04 17:46 ` Paolo Valente [this message]
2021-03-04 17:46 ` [PATCH BUGFIX/IMPROVEMENT V2 5/6] block, bfq: keep shared queues out of the waker mechanism Paolo Valente
2021-03-04 17:46 ` [PATCH BUGFIX/IMPROVEMENT V2 6/6] block, bfq: merge bursts of newly-created queues Paolo Valente
2021-03-20 16:35 ` [PATCH BUGFIX/IMPROVEMENT V2 0/6] revised version of third and last batch of patches Paolo Valente
2021-03-25 8:03 ` Oleksandr Natalenko
2021-03-25 16:50 ` Jens Axboe
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