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Subject: Re: [PATCH] blkcg: add plugging support for punt bio
To:     Xianting Tian <xianting_tian@126.com>, tj@kernel.org
Cc:     cgroups@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org
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From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <8f84e1fe-9fa5-b7e7-1f2f-b0c4a40614e2@kernel.dk>
Date:   Thu, 6 Aug 2020 09:16:34 -0600
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On 8/6/20 7:54 AM, Xianting Tian wrote:
> Try to merge continuous bio to current task's plug fisrt.

The patch looks fine to me, but I'd really like to see a bit more
changelog here. The commit message should explain why the change
is made, rather it's a very brief explanation of what it does.

If the bio list is contiguous, then we do the plugging to improve
merging at the lower level. You probably ran into a case where
you saw sub-optimal merging? And now the performance is better
with the patch? How much?


-- 
Jens Axboe