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From: Sasha Levin <sashal@kernel.org>
To: Eric Wheeler <stable@lists.ewheeler.net>
Cc: Paolo Valente <paolo.valente@linaro.org>,
	Jens Axboe <axboe@kernel.dk>,
	"open list:BFQ I/O SCHEDULER" <linux-block@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	Eric Wheeler <bfq@linux.ewheeler.net>,
	stable@vger.kernel.org
Subject: Re: [PATCH] bfq: backport: update internal depth state when queue depth changes
Date: Fri, 10 May 2019 16:18:55 -0400	[thread overview]
Message-ID: <20190510201855.GB14410@sasha-vm> (raw)
In-Reply-To: <1557510992-18506-1-git-send-email-stable@lists.ewheeler.net>

On Fri, May 10, 2019 at 10:56:32AM -0700, Eric Wheeler wrote:
>From: Jens Axboe <axboe@kernel.dk>
>
>commit 77f1e0a52d26242b6c2dba019f6ebebfb9ff701e upstream
>
>A previous commit moved the shallow depth and BFQ depth map calculations
>to be done at init time, moving it outside of the hotter IO path. This
>potentially causes hangs if the users changes the depth of the scheduler
>map, by writing to the 'nr_requests' sysfs file for that device.
>
>Add a blk-mq-sched hook that allows blk-mq to inform the scheduler if
>the depth changes, so that the scheduler can update its internal state.
>
>Signed-off-by: Eric Wheeler <bfq@linux.ewheeler.net>
>Tested-by: Kai Krakow <kai@kaishome.de>
>Reported-by: Paolo Valente <paolo.valente@linaro.org>
>Fixes: f0635b8a416e ("bfq: calculate shallow depths at init time")
>Signed-off-by: Jens Axboe <axboe@kernel.dk>
>Cc: stable@vger.kernel.org

I wasn't clear on what was backported here, so I've queued the upstream
version on 4.19 and 4.14, it doesn't seem to be relevant to older
branches.

--
Thanks,
Sasha

  reply	other threads:[~2019-05-10 20:18 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-10 17:56 [PATCH] bfq: backport: update internal depth state when queue depth changes Eric Wheeler
2019-05-10 20:18 ` Sasha Levin [this message]
2019-05-10 23:17   ` Eric Wheeler
2019-05-10 23:58     ` Holger Hoffstätte
2019-05-13  7:03   ` Greg KH
2019-05-13 13:09     ` Sasha Levin

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