From: Jens Axboe <axboe@kernel.dk>
To: Harshad Shirwadkar <harshadshirwadkar@gmail.com>,
linux-kernel@vger.kernel.org
Cc: linux-block@vger.kernel.org, vaibhavrustagi@google.com,
Josef Bacik <jbacik@fb.com>
Subject: Re: [PATCH v2] blk-wbt: fix performance regression in wbt scale_up/scale_down
Date: Sun, 6 Oct 2019 09:25:10 -0600 [thread overview]
Message-ID: <946f4a47-c4ad-0b2e-4a5b-d0873cbcb510@kernel.dk> (raw)
In-Reply-To: <20191005185927.91209-1-harshadshirwadkar@gmail.com>
On 10/5/19 12:59 PM, Harshad Shirwadkar wrote:
> scale_up wakes up waiters after scaling up. But after scaling max, it
> should not wake up more waiters as waiters will not have anything to
> do. This patch fixes this by making scale_up (and also scale_down)
> return when threshold is reached.
>
> This bug causes increased fdatasync latency when fdatasync and dd
> conv=sync are performed in parallel on 4.19 compared to 4.14. This
> bug was introduced during refactoring of blk-wbt code.
Nice catch, thanks, applied.
--
Jens Axboe
prev parent reply other threads:[~2019-10-06 15:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-05 18:59 Harshad Shirwadkar
2019-10-06 15:25 ` Jens Axboe [this message]
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