From: Jens Axboe <axboe@kernel.dk>
To: Christoph Hellwig <hch@infradead.org>
Cc: Yu Kuai <yukuai3@huawei.com>,
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 08:41:57 -0600 [thread overview]
Message-ID: <338207c2-e3cd-abc1-6b8c-f08645ef144a@kernel.dk> (raw)
In-Reply-To: <YkMabVKr+7Mg53E1@infradead.org>
On 3/29/22 8:40 AM, Christoph Hellwig wrote:
> On Tue, Mar 29, 2022 at 08:35:29AM -0600, Jens Axboe wrote:
>>> 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?
>>
>> See the posted use case, it's running 512kb ios on a 128kb device.
>
> That is an awfully low limit these days. I'm really not sure we should
> optimize the block layer for that.
That's exactly what my replies have been saying. I don't think this is
a relevant thing to optimize for.
Fixing fairness for wakeups seems useful, however.
--
Jens Axboe
next prev parent reply other threads:[~2022-03-29 14:42 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
2022-03-29 14:35 ` Jens Axboe
2022-03-29 14:40 ` Christoph Hellwig
2022-03-29 14:41 ` Jens Axboe [this message]
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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