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Date: Tue, 12 May 2015 00:25:23 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Ming Lei <ming.lei@canonical.com>
Cc: Christoph Hellwig <hch@infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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        Andrew Morton <akpm@linux-foundation.org>,
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Subject: Re: [PATCH v3 3/4] block: loop: use kthread_work
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On Mon, May 11, 2015 at 09:12:56PM +0800, Ming Lei wrote:
> For non-AIO case, single thread has been used for long long time,
> and it was just converted to work in v4.0, which has caused performance
> regression for fedora live booting already. In discussion[1], even though
> submitting I/O via work concurrently can improve random IO throughput,
> meantime it may hurt sequential IO performance, so maybe better to restore
> to single thread behaviour.

Then justify the change based on the non-aio use case and document that
in the changelog.