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Subject: Re: [PATCH BUGFIX] block, bfq: deschedule empty bfq_queues not
 referred by any process
From:   Paolo Valente <paolo.valente@linaro.org>
In-Reply-To: <8f77fb4e-a49b-4ddc-8756-e08b030dd7e4@kernel.dk>
Date:   Thu, 14 Nov 2019 10:22:01 +0100
Cc:     Oleksandr Natalenko <oleksandr@natalenko.name>,
        linux-block <linux-block@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        bfq-iosched@googlegroups.com, Chris Evich <cevich@redhat.com>,
        Patrick Dung <patdung100@gmail.com>,
        Thorsten Schubert <tschubert@bafh.org>
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Message-Id: <CC298DB4-3107-4E9A-AD11-47AA070D85EF@linaro.org>
References: <20191112074856.40433-1-paolo.valente@linaro.org>
 <bb393dcaa426786e0963cf0e70f0b062@natalenko.name>
 <2FB3736A-693E-44B9-9D1F-39AE0D016644@linaro.org>
 <65fc0bffbcb2296d121b3d5a79108e76@natalenko.name>
 <5773ff54421ccf179ef57d96e19ef042@natalenko.name>
 <69B451DE-B04B-4E0E-9464-826C4A7619AD@linaro.org>
 <8f77fb4e-a49b-4ddc-8756-e08b030dd7e4@kernel.dk>
To:     Jens Axboe <axboe@kernel.dk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> Il giorno 13 nov 2019, alle ore 23:46, Jens Axboe <axboe@kernel.dk> ha =
scritto:
>=20
> On 11/13/19 10:42 AM, Paolo Valente wrote:
>>=20
>>=20
>>> Il giorno 13 nov 2019, alle ore 16:01, Oleksandr Natalenko =
<oleksandr@natalenko.name> ha scritto:
>>>=20
>>> On 13.11.2019 15:25, Oleksandr Natalenko wrote:
>>>> I didn't try to switch schedulers, but what I see now is once the
>>>> system is able to boot with BFQ, the I/O can still hang on I/O =
burst
>>>> (which for me happens to happen during VM reboot).
>>>> This may also not hang forever, but just slow down considerably. =
I've
>>>> noticed this inside a KVM VM, not on a real HW.
>>>=20
>>> Possible call traces:
>>=20
>> Ok, you may have given me enough information, thank you very much.
>>=20
>> Could you please apply the attached (compressed) patch on top of my
>> offending patch?  For review purposes, here is the simple change:
>=20
> FWIW, I dropped the previous patch.
>=20

Thanks. I'm sending a V2.

Thanks,
Paolo

> --=20
> Jens Axboe