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From: Ming Lei <ming.lei@redhat.com>
To: "yukuai (C)" <yukuai3@huawei.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org, yi.zhang@huawei.com,
	zhangxiaoxu5@huawei.com
Subject: Re: [PATCH 1/3] blk-mq: allow hardware queue to get more tag while sharing a tag set
Date: Tue, 29 Dec 2020 09:15:17 +0800	[thread overview]
Message-ID: <20201229011517.GA3355551@T590> (raw)
In-Reply-To: <fce32e47-0e7d-39fa-611f-31ac0b422ba5@huawei.com>

On Mon, Dec 28, 2020 at 05:02:50PM +0800, yukuai (C) wrote:
> Hi
> 
> On 2020/12/28 16:28, Ming Lei wrote:
> > Another candidate solution may be to always return true from hctx_may_queue()
> > for this kind of queue because queue_depth has provided fair allocation for
> > each LUN, and looks not necessary to do that again.
> 
> If always return true from hctx_may_queue() in this case, for example,
> we set queue_depth to 128(if can't, the biggger, the better) for all
> disks, and test with numjobs=64. The result should be one disk with high
> iops, and the rest very low. So I think it's better to ensure the max
> tags a disk can get in this case.

Just wondering why you try to set 128 via sysfs for all disks? If you do that,
you should know the potential result given the whole tags queue depth is just
128.


Thanks,
Ming


  reply	other threads:[~2020-12-29  1:17 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-26 10:28 [PATCH 0/3] fix the performance fluctuation due to shared tagset Yu Kuai
2020-12-26 10:28 ` [PATCH 1/3] blk-mq: allow hardware queue to get more tag while sharing a tag set Yu Kuai
2020-12-27 11:58   ` Ming Lei
2020-12-28  1:56     ` yukuai (C)
2020-12-28  8:28       ` Ming Lei
2020-12-28  9:02         ` yukuai (C)
2020-12-29  1:15           ` Ming Lei [this message]
2020-12-29  2:37             ` yukuai (C)
2020-12-26 10:28 ` [PATCH 2/3] blk-mq: clear 'active_queues' immediately when 'nr_active' is decreased to 0 Yu Kuai
2020-12-26 10:28 ` [PATCH 3/3] blk-mq: decrease pending_queues when it expires Yu Kuai

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