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Subject: Re: [PATCH BUGFIX] block, bfq: deschedule empty bfq_queues not
 referred by any process
To:     Paolo Valente <paolo.valente@linaro.org>,
        Oleksandr Natalenko <oleksandr@natalenko.name>
Cc:     linux-block <linux-block@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>, linus.walleij@linaro.org,
        bfq-iosched@googlegroups.com, Chris Evich <cevich@redhat.com>,
        Patrick Dung <patdung100@gmail.com>,
        Thorsten Schubert <tschubert@bafh.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>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <8f77fb4e-a49b-4ddc-8756-e08b030dd7e4@kernel.dk>
Date:   Wed, 13 Nov 2019 15:46:37 -0700
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On 11/13/19 10:42 AM, Paolo Valente wrote:
> 
> 
>> Il giorno 13 nov 2019, alle ore 16:01, Oleksandr Natalenko <oleksandr@natalenko.name> ha scritto:
>>
>> 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.
>>
>> Possible call traces:
> 
> Ok, you may have given me enough information, thank you very much.
> 
> Could you please apply the attached (compressed) patch on top of my
> offending patch?  For review purposes, here is the simple change:

FWIW, I dropped the previous patch.

-- 
Jens Axboe