linux-kernel - Re: [PATCH] vmscan: Stop kswapd waiting on congestion when the min watermark is not being met V2

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Message-ID: <alpine.DEB.2.00.0911261542500.21450@sebohet.brgvxre.pu>
Date:	Thu, 26 Nov 2009 15:45:13 +0100 (CET)
From:	Tobias Oetiker <tobi@...iker.ch>
To:	Mel Gorman <mel@....ul.ie>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Frans Pop <elendil@...net.nl>, Jiri Kosina <jkosina@...e.cz>,
	Sven Geggus <lists@...hsschwanzdomain.de>,
	Karol Lewandowski <karol.k.lewandowski@...il.com>,
	linux-kernel@...r.kernel.org,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Rik van Riel <riel@...hat.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Stephan von Krawczynski <skraw@...net.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Kernel Testers List <kernel-testers@...r.kernel.org>
Subject: Re: [PATCH] vmscan: Stop kswapd waiting on congestion when the min
 watermark is not being met V2

Hi Mel,

Nov 13 Mel Gorman wrote:

> The last version has a stupid bug in it. Sorry.
>
> Changelog since V1
>   o Fix incorrect negation
>   o Rename kswapd_no_congestion_wait to kswapd_skip_congestion_wait as
>     suggested by Rik
>
> If reclaim fails to make sufficient progress, the priority is raised.
> Once the priority is higher, kswapd starts waiting on congestion.  However,
> if the zone is below the min watermark then kswapd needs to continue working
> without delay as there is a danger of an increased rate of GFP_ATOMIC
> allocation failure.
>
> This patch changes the conditions under which kswapd waits on
> congestion by only going to sleep if the min watermarks are being met.

I finally got around to test this together with the whole series on
2.6.31.6. after running it for a day I have not yet seen a single
order:5 allocation problem ... (while I had several an hour before)

for the record, my kernel is now running with the following
patches:

patch1:Date: Thu, 12 Nov 2009 19:30:31 +0000
patch1:Subject: [PATCH 1/5] page allocator: Always wake kswapd when restarting an allocation attempt after direct reclaim failed

patch2:Date: Thu, 12 Nov 2009 19:30:32 +0000
patch2:Subject: [PATCH 2/5] page allocator: Do not allow interrupts to use ALLOC_HARDER

patch3:Date: Thu, 12 Nov 2009 19:30:33 +0000
patch3:Subject: [PATCH 3/5] page allocator: Wait on both sync and async congestion after direct reclaim

patch4:Date: Thu, 12 Nov 2009 19:30:34 +0000
patch4:Subject: [PATCH 4/5] vmscan: Have kswapd sleep for a short interval and double check it should be asleep

patch5:Date: Fri, 13 Nov 2009 20:03:57 +0000
patch5:Subject: [PATCH] vmscan: Stop kswapd waiting on congestion when the min watermark is not being met V2

patch6:Date: Tue, 17 Nov 2009 10:34:21 +0000
patch6:Subject: [PATCH] vmscan: Have kswapd sleep for a short interval and double check it should be asleep fix 1

cheers
tobi

-- 
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi@...iker.ch ++41 62 775 9902 / sb: -9900
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