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Subject: Re: [PATCH 2/5] writeback: dirty position control
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 26 Aug 2011 14:11:50 +0200
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To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>, "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@lst.de>, Dave Chinner <david@fromorbit.com>, Greg Thelen <gthelen@google.com>, Minchan Kim <minchan.kim@gmail.com>, Andrea Righi <arighi@develer.com>, linux-mm <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>

On Fri, 2011-08-26 at 19:26 +0800, Wu Fengguang wrote:
> Now I get 3 figures. Test case is: run 1 dd write task for 300s, with
> a "disturber" dd read task during roughly 120-130s.=20

Ah, but ideally the disturber task should run in bursts of 100ms
(<feedback period), otherwise your N is indeed mostly constant.


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