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From: Jan Kara <jack@suse.cz>
To: Yu Kuai <yukuai3@huawei.com>
Cc: tj@kernel.org, axboe@kernel.dk, paolo.valente@linaro.org,
	jack@suse.cz, cgroups@vger.kernel.org,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	yi.zhang@huawei.com
Subject: Re: [PATCH -next 00/11] support concurrent sync io for bfq on a specail occasion
Date: Wed, 13 Apr 2022 13:12:16 +0200	[thread overview]
Message-ID: <20220413111216.npgrdzaubsvjsmy3@quack3.lan> (raw)
In-Reply-To: <20220305091205.4188398-1-yukuai3@huawei.com>

On Sat 05-03-22 17:11:54, Yu Kuai wrote:
> Currently, bfq can't handle sync io concurrently as long as they
> are not issued from root group. This is because
> 'bfqd->num_groups_with_pending_reqs > 0' is always true in
> bfq_asymmetric_scenario().
> 
> This patchset tries to support concurrent sync io if all the sync ios
> are issued from the same cgroup:
> 
> 1) Count root_group into 'num_groups_with_pending_reqs', patch 1-5;

Seeing the complications and special casing for root_group I wonder: Won't
we be better off to create fake bfq_sched_data in bfq_data and point
root_group->sched_data there? AFAICS it would simplify the code
considerably as root_group would be just another bfq_group, no need to
special case it in various places, no games with bfqg->my_entity, etc.
Paolo, do you see any problem with that?

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  parent reply	other threads:[~2022-04-13 11:12 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-05  9:11 [PATCH -next 00/11] support concurrent sync io for bfq on a specail occasion Yu Kuai
2022-03-05  9:11 ` [PATCH -next 01/11] block, bfq: add new apis to iterate bfq entities Yu Kuai
2022-03-05  9:11 ` [PATCH -next 02/11] block, bfq: apply news apis where root group is not expected Yu Kuai
2022-04-13  9:50   ` Jan Kara
2022-04-13 10:59     ` Jan Kara
2022-04-13 11:11       ` yukuai (C)
2022-03-05  9:11 ` [PATCH -next 03/11] block, bfq: cleanup for __bfq_activate_requeue_entity() Yu Kuai
2022-03-05  9:11 ` [PATCH -next 04/11] block, bfq: move the increasement of 'num_groups_with_pending_reqs' to it's caller Yu Kuai
2022-03-05  9:11 ` [PATCH -next 05/11] block, bfq: count root group into 'num_groups_with_pending_reqs' Yu Kuai
2022-04-13 11:05   ` Jan Kara
2022-03-05  9:12 ` [PATCH -next 06/11] block, bfq: do not idle if only one cgroup is activated Yu Kuai
2022-03-05  9:12 ` [PATCH -next 07/11] block, bfq: only count parent bfqg when bfqq " Yu Kuai
2022-03-05  9:12 ` [PATCH -next 08/11] block, bfq: record how many queues have pending requests in bfq_group Yu Kuai
2022-03-05  9:12 ` [PATCH -next 09/11] block, bfq: move forward __bfq_weights_tree_remove() Yu Kuai
2022-03-05  9:12 ` [PATCH -next 10/11] block, bfq: decrease 'num_groups_with_pending_reqs' earlier Yu Kuai
2022-04-13 11:28   ` Jan Kara
2022-04-13 11:40     ` yukuai (C)
2022-04-15  1:10       ` yukuai (C)
2022-04-19  9:49         ` Jan Kara
2022-04-19 11:37           ` yukuai (C)
2022-04-21  8:17             ` Jan Kara
2022-03-05  9:12 ` [PATCH -next 11/11] block, bfq: cleanup bfqq_group() Yu Kuai
2022-03-11  6:31 ` [PATCH -next 00/11] support concurrent sync io for bfq on a specail occasion yukuai (C)
2022-03-17  1:49   ` yukuai (C)
2022-03-18 12:38     ` Paolo Valente
2022-03-19  2:34       ` yukuai (C)
2022-03-25  7:30     ` yukuai (C)
2022-04-01  3:43       ` yukuai (C)
2022-04-08  6:50         ` yukuai (C)
2022-04-13 11:12 ` Jan Kara [this message]
2022-04-13 11:33   ` yukuai (C)
2022-04-26 14:24   ` Paolo Valente

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