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Date: Thu, 21 Apr 2011 11:01:32 +1000
From: Dave Chinner <david@fromorbit.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>, Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mel@linux.vnet.ibm.com>, Mel Gorman <mel@csn.ul.ie>,
        Trond Myklebust <Trond.Myklebust@netapp.com>,
        Itaru Kitayama <kitayama@cl.bb4u.ne.jp>,
        Minchan Kim <minchan.kim@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [PATCH 3/6] writeback: sync expired inodes first in background
 writeback
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On Wed, Apr 20, 2011 at 03:38:22PM +0800, Wu Fengguang wrote:
> > make. Please test against a vanilla kernel if that is what you are
> > aiming these patches for. If you aren't aiming for a vanilla kernel,
> > please say so in the patch series header...
> 
> Here are the test results for vanilla kernel. It's again shows better
> numbers for dd, tar and overall run time.
> 
>              2.6.39-rc3   2.6.39-rc3-dyn-expire+
> ------------------------------------------------
> all elapsed     256.043      252.367
> stddev           24.381       12.530
> 
> tar elapsed      30.097       28.808
> dd  elapsed      13.214       11.782

The big reduction in run-to-run variance is very convincing - moreso
than the reduction in runtime - That's kind of what I had hoped
would occur once I understood the implications of the change. Thanks
for running the test to close the loop. :)

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com