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From: Christoph Hellwig <hch@infradead.org>
To: Yu Kuai <yukuai3@huawei.com>
Cc: axboe@kernel.dk, andriy.shevchenko@linux.intel.com,
	john.garry@huawei.com, ming.lei@redhat.com,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	yi.zhang@huawei.com
Subject: Re: [PATCH -next RFC 2/6] block: refactor to split bio thoroughly
Date: Tue, 29 Mar 2022 06:32:51 -0700	[thread overview]
Message-ID: <YkMKgwsZ3K8dRVbX@infradead.org> (raw)
In-Reply-To: <20220329094048.2107094-3-yukuai3@huawei.com>

On Tue, Mar 29, 2022 at 05:40:44PM +0800, Yu Kuai wrote:
> Currently, the splited bio is handled first, and then continue to split
> the original bio. This patch tries to split the original bio thoroughly,
> so that it can be known in advance how many tags will be needed.

How do you avoid the deadlock risk with all the split bios being
submitted together?

But more importantly why does your use case even have splits that get
submitted together?  Is this a case of Linus' stupidly low default
max_sectors when the hardware supports more, or is the hardware limited
to a low number of sectors per request?  Or do we hit another reason
for the split?


  parent reply	other threads:[~2022-03-29 13:33 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-29  9:40 [PATCH -next RFC 0/6] improve large random io for HDD Yu Kuai
2022-03-29  9:40 ` [PATCH -next RFC 1/6] blk-mq: add a new flag 'BLK_MQ_F_NO_TAG_PREEMPTION' Yu Kuai
2022-03-29 12:44   ` Jens Axboe
2022-03-30  1:18     ` yukuai (C)
2022-03-30  1:20       ` Jens Axboe
2022-03-29  9:40 ` [PATCH -next RFC 2/6] block: refactor to split bio thoroughly Yu Kuai
2022-03-29 12:46   ` Jens Axboe
2022-03-30  1:35     ` yukuai (C)
2022-03-29 13:32   ` Christoph Hellwig [this message]
2022-03-29 14:35     ` Jens Axboe
2022-03-29 14:40       ` Christoph Hellwig
2022-03-29 14:41         ` Jens Axboe
2022-03-29 14:42           ` Christoph Hellwig
2022-03-30  1:54           ` yukuai (C)
2022-03-29  9:40 ` [PATCH -next RFC 3/6] blk-mq: record how many tags are needed for splited bio Yu Kuai
2022-03-29  9:40 ` [PATCH -next RFC 4/6] sbitmap: wake up the number of threads based on required tags Yu Kuai
2022-03-29  9:40 ` [PATCH -next RFC 5/6] blk-mq: don't preempt tag expect for split bios Yu Kuai
2022-03-29  9:40 ` [PATCH -next RFC 6/6] sbitmap: force tag preemption if free tags are sufficient Yu Kuai
2022-03-29 12:53 ` [PATCH -next RFC 0/6] improve large random io for HDD Jens Axboe
2022-03-30  2:05   ` yukuai (C)

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