linux-kernel - Re: [PATCH v3 3/4] block: loop: use kthread

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Message-ID: <CACVXFVPQNvL+dtR5y1dR+GUxfY_Li4WkRcvXJsutT5dXL2FsvA@mail.gmail.com>
Date:	Thu, 7 May 2015 18:32:03 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Christoph Hellwig <hch@...radead.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dave Kleikamp <dave.kleikamp@...cle.com>,
	Jens Axboe <axboe@...nel.dk>, Zach Brown <zab@...bo.net>,
	Maxim Patlasov <mpatlasov@...allels.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH v3 3/4] block: loop: use kthread_work

On Thu, May 7, 2015 at 3:17 PM, Christoph Hellwig <hch@...radead.org> wrote:
> On Thu, May 07, 2015 at 01:08:25AM +0800, Ming Lei wrote:
>> The following patch will use dio/aio to submit IO to backing file,
>> then it isn't good to schedule IO concurrently from work, so
>> use kthread_work.
>
> I can't really parse this, what's the specific advantage here?

Patch 4's commit log provides the test data.

>From the data, it is observed that one thread is enough to get
similar throughput with previous one which submits IO from
work concurrently.

Single thread can decrease context switch a lots, also one thread is
often used to submit AIO in reality.

Thanks,
Ming Lei
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