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Subject: Re: [PATCH 0/2] Fix misuse of blk_rq_stats in blk-iolatency
From:   Pavel Begunkov <asml.silence@gmail.com>
To:     Josef Bacik <josef@toxicpanda.com>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, dennis@kernel.org
References: <cover.1560510935.git.asml.silence@gmail.com>
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Message-ID: <226043f8-4dc6-1ad3-7c66-8d85312f4cae@gmail.com>
Date:   Sat, 29 Jun 2019 08:37:48 -0700
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From: Pavel Begunkov <asml.silence@gmail.com>
To: Josef Bacik <josef@toxicpanda.com>
Cc: Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
 linux-kernel@vger.kernel.org, dennis@kernel.org
Message-ID: <226043f8-4dc6-1ad3-7c66-8d85312f4cae@gmail.com>
Subject: Re: [PATCH 0/2] Fix misuse of blk_rq_stats in blk-iolatency
References: <cover.1560510935.git.asml.silence@gmail.com>
 <20190614134037.ie7zs4rb4oyesifr@MacBook-Pro-91.local>
 <054f3ab6-0a03-ff0e-ac46-5d0fba012cf0@gmail.com>
In-Reply-To: <054f3ab6-0a03-ff0e-ac46-5d0fba012cf0@gmail.com>

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Ping?

On 20/06/2019 10:18, Pavel Begunkov wrote:
> Hi,
>=20
> Josef, thanks for taking a look.
>=20
>=20
> Although, there is nothing critical yet -- just a not working / disable=
d
> optimisation, but changes in stats could sublty break it. E.g. grouping=

> @batch and @mean into a union will increase estimated average by severa=
l
> orders of magnitude.
>=20
> Jens, what do you think?
>=20
>=20
>=20
> On 14/06/2019 16:40, Josef Bacik wrote:
>> On Fri, Jun 14, 2019 at 02:44:11PM +0300, Pavel Begunkov (Silence) wro=
te:
>>> From: Pavel Begunkov <asml.silence@gmail.com>
>>>
>>> There are implicit assumptions about struct blk_rq_stats, which make
>>> it's very easy to misuse. The first patch fixes consequences, and the=

>>> second employs type-system to prevent recurrences.
>>>
>>>
>>> Pavel Begunkov (2):
>>>   blk-iolatency: Fix zero mean in previous stats
>>>   blk-stats: Introduce explicit stat staging buffers
>>>
>>
>> I don't have a problem with this, but it's up to Jens I suppose
>>
>> Acked-by: Josef Bacik <josef@toxicpanda.com>
>>
>> Thanks,
>>
>> Josef
>>
>=20

--=20
Yours sincerely,
Pavel Begunkov


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