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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 <linux-block@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <yi.zhang@huawei.com>
Subject: Re: [PATCH v2 2/4] block, bfq: do not idle if only one cgroup is activated
Date: Tue, 7 Sep 2021 19:19:20 +0800	[thread overview]
Message-ID: <f7900f33-5f27-a6e3-ee3d-f68ad9d8a6d3@huawei.com> (raw)
In-Reply-To: <F1ADC992-11AE-4511-9033-D233CBCA6F26@linaro.org>

On 2021/09/07 17:10, Paolo Valente wrote:
> 
> 
>> Il giorno 2 set 2021, alle ore 15:31, yukuai (C) <yukuai3@huawei.com> ha scritto:
>>
>> On 2021/08/27 1:00, Paolo Valente wrote:
>>> Why do you make these extensive changes, while you can leave all the
>>> function unchanged and just modify the above condition to something
>>> like
>>> || bfqd->num_groups_with_pending_reqs > 1
>>> || (bfqd->num_groups_with_pending_reqs && bfqd->num_queues_with_pending_reqs_in_root)
>>
>> Hi, Paolo
>>
>> I was thinking that if CONFIG_BFQ_GROUP_IOSCHED is enabled, there is no
>> need to caculate smallest_weight, varied_queue_weights, and
>> multiple_classes_busy:
>>
>> If we count root group into num_groups_with_pending_reqs
>> - If num_groups_with_pending_reqs <= 1, idle is not needed
> 
> Unfortunately, if active queues have different weights or belong to
> different classes, then idling is needed to preserve per-queue
> bandwidths.
> 
> Thanks,
> Paolo

Hi, Paolo

It's right, if num_groups_with_pending_reqs == 1, multiple_classes_busy
should be checked, while smallest_weight and varied_queue_weights can
be skipped.

Thanks
Kuai

> .
> 

  reply	other threads:[~2021-09-07 11:19 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-06  2:08 [PATCH v2 0/4] optimize the bfq queue idle judgment Yu Kuai
2021-08-06  2:08 ` [PATCH v2 1/4] block, bfq: add support to track if root_group have any pending requests Yu Kuai
2021-08-26 17:00   ` Paolo Valente
2021-09-02 13:23     ` yukuai (C)
2021-08-06  2:08 ` [PATCH v2 2/4] block, bfq: do not idle if only one cgroup is activated Yu Kuai
2021-08-26 17:00   ` Paolo Valente
2021-09-02 13:31     ` yukuai (C)
2021-09-07  9:10       ` Paolo Valente
2021-09-07 11:19         ` yukuai (C) [this message]
2021-08-06  2:08 ` [PATCH v2 3/4] block, bfq: add support to record request size information Yu Kuai
2021-08-26 17:00   ` Paolo Valente
2021-08-06  2:08 ` [PATCH v2 4/4] block, bfq: consider request size in bfq_asymmetric_scenario() Yu Kuai
2021-08-26 17:00   ` Paolo Valente
2021-09-07 11:29     ` yukuai (C)
2021-09-15  7:36       ` Paolo Valente
2021-09-15  7:47         ` yukuai (C)
2021-08-14  2:34 ` [PATCH v2 0/4] optimize the bfq queue idle judgment yukuai (C)
2021-08-24 14:09   ` yukuai (C)
2021-08-26 16:59 ` Paolo Valente

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