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Date: Tue, 13 Jan 2015 08:23:07 -0800
From: Christoph Hellwig <hch@infradead.org>
To: Ming Lei <ming.lei@canonical.com>
Cc: linux-kernel@vger.kernel.org, Dave Kleikamp <dave.kleikamp@oracle.com>,
        Jens Axboe <axboe@kernel.dk>, Zach Brown <zab@zabbo.net>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Benjamin LaHaise <bcrl@kvack.org>
Subject: Re: [PATCH v2 0/4] block & aio: improve loop with kernel aio
Message-ID: <20150113162307.GA21338@infradead.org>
References: <1421163888-21452-1-git-send-email-ming.lei@canonical.com>
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On Tue, Jan 13, 2015 at 11:44:44PM +0800, Ming Lei wrote:
> Follows benefits from using kernel aio in loop:
> 	- avoid double cache, and memory usage decreased a lot
> 	- system load gets much decreased

This seems to conflate two changes:

 1) use direct I/O
 2) use aio (require 1)

what numbers do you get when just using direct I/O?