* [PATCH AUTOSEL 5.12 061/134] block, bfq: fix weight-raising resume with !low_latency
[not found] <20210503163513.2851510-1-sashal@kernel.org>
@ 2021-05-03 16:34 ` Sasha Levin
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From: Sasha Levin @ 2021-05-03 16:34 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Paolo Valente, Jan Kara, Oleksandr Natalenko, Jens Axboe,
Sasha Levin, linux-block
From: Paolo Valente <paolo.valente@linaro.org>
[ Upstream commit 8c544770092a3d7532d01903b75721e537d87001 ]
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>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Link: https://lore.kernel.org/r/20210304174627.161-5-paolo.valente@linaro.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.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 95586137194e..20ba5db0f61c 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -1012,7 +1012,7 @@ 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)
@@ -1033,7 +1033,13 @@ 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;
--
2.30.2
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2021-05-03 16:34 ` [PATCH AUTOSEL 5.12 061/134] block, bfq: fix weight-raising resume with !low_latency Sasha Levin
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