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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Subject: Re: [PATCH] mm: use pagevec to rotate reclaimable page
Date: Tue, 18 Sep 2007 11:29:50 +1000
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Cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org
References: <6.0.0.20.2.20070907113025.024dfbb8@172.19.0.2> <20070913193711.ecc825f7.akpm@linux-foundation.org> <6.0.0.20.2.20070918193944.038e2ea0@172.19.0.2>
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On Tuesday 18 September 2007 20:41, Hisashi Hifumi wrote:
> I modified my patch based on your comment.
>
> At 11:37 07/09/14, Andrew Morton wrote:
>  >So I do think that for safety and sanity's sake, we should be taking a
>  > ref on the pages when they are in a pagevec.  That's going to hurt your
>  > nice performance numbers :(
>
> I did ping test again to observe performance deterioration caused by taking
> a ref.
>
> 	-2.6.23-rc6-with-modifiedpatch
> 	--- testmachine ping statistics ---
> 	3000 packets transmitted, 3000 received, 0% packet loss, time 53386ms
> 	rtt min/avg/max/mdev = 0.074/0.110/4.716/0.147 ms, pipe 2, ipg/ewma
> 17.801/0.129 ms
>
> The result for my original patch is as follows.
>
> 	-2.6.23-rc5-with-originalpatch
> 	--- testmachine ping statistics ---
> 	3000 packets transmitted, 3000 received, 0% packet loss, time 51924ms
> 	rtt min/avg/max/mdev = 0.072/0.108/3.884/0.114 ms, pipe 2, ipg/ewma
> 17.314/0.091 ms
>
>
> The influence to response was small.

It would be interesting to test -mm kernels. They have a patch which reduces
zone lock contention quite a lot.

I think your patch is a nice idea, and with less zone lock contention in other
areas, it is possible that it might produce a relatively larger improvement.
-
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