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From: "yukuai (C)" <yukuai3@huawei.com>
To: Paolo Valente <paolo.valente@linaro.org>
Cc: Jens Axboe <axboe@kernel.dk>, <linux-block@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <yi.zhang@huawei.com>
Subject: Re: [PATCH 1/3] block, bfq: do not idle if only one cgroup is activated
Date: Mon, 26 Jul 2021 09:15:54 +0800	[thread overview]
Message-ID: <fd21f7c8-2b13-f638-3114-9d95df9bc082@huawei.com> (raw)
In-Reply-To: <7DF40BD4-8F57-4C2E-88A9-CBC3DA2A891E@linaro.org>

On 2021/07/24 15:12, Paolo Valente wrote:
> 
> 
>> Il giorno 14 lug 2021, alle ore 11:45, Yu Kuai <yukuai3@huawei.com> ha scritto:
>>
>> If only one group is activated, specifically
>> 'bfqd->num_groups_with_pending_reqs == 1', there is no need to guarantee
>> the same share of the throughput of queues in the same group.
>>
>> Thus change the condition from '> 0' to '> 1' in
>> bfq_asymmetric_scenario().
> 
> I see your point, and I agree with your goal.  Yet, your change seems
> not to suffer from the following problem.
> 
> In addition to the groups that are created explicitly, there is the
> implicit root group.  So, when bfqd->num_groups_with_pending_reqs ==
> 1, there may be both active processes in the root group and active
> processes in the only group created explicitly.  In this case, idling
> is needed to preserve service guarantees.
> 
> Probably your idea should be improved by making sure that there is
> pending I/O only from either the root group or the explicit group.
> 
> Thanks,
> Paolo
> 

Hi,

Thanks for you advice, will do this in the next iteration.

Best regards,
Kuai

  reply	other threads:[~2021-07-26  1:16 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14  9:45 [PATCH 0/3] optimize the queue idle judgment Yu Kuai
2021-07-14  9:45 ` [PATCH 1/3] block, bfq: do not idle if only one cgroup is activated Yu Kuai
2021-07-24  7:12   ` Paolo Valente
2021-07-26  1:15     ` yukuai (C) [this message]
2021-07-31  7:10     ` yukuai (C)
2021-08-03  7:07       ` Paolo Valente
2021-08-03 11:30         ` yukuai (C)
2021-07-14  9:45 ` [PATCH 2/3] block, bfq: add support to record request size information Yu Kuai
2021-07-14  9:45 ` [PATCH 3/3] block, bfq: consider request size in bfq_asymmetric_scenario() Yu Kuai
2021-07-20 12:33 ` [PATCH 0/3] optimize the queue idle judgment yukuai (C)

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