Date: Tue, 27 Oct 2009 15:19:05 +0000
From: Mel Gorman <mel@csn.ul.ie>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: Stephan von Krawczynski <skraw@ithnet.com>, Frans Pop <elendil@planet.nl>,
       Jiri Kosina <jkosina@suse.cz>,
       Sven Geggus <lists@fuchsschwanzdomain.de>,
       Karol Lewandowski <karol.k.lewandowski@gmail.com>,
       Tobias Oetiker <tobi@oetiker.ch>, "Rafael J. Wysocki" <rjw@sisk.pl>,
       David Miller <davem@davemloft.net>,
       Reinette Chatre <reinette.chatre@intel.com>,
       Kalle Valo <kalle.valo@iki.fi>, David Rientjes <rientjes@google.com>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Mohamed Abbas <mohamed.abbas@intel.com>,
       Jens Axboe <jens.axboe@oracle.com>,
       "John W. Linville" <linville@tuxdriver.com>,
       Pekka Enberg <penberg@cs.helsinki.fi>,
       Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>,
       Greg Kroah-Hartman <gregkh@suse.de>,
       Kernel Testers List <kernel-testers@vger.kernel.org>,
       netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
       "linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH 2/5] page allocator: Do not allow interrupts to use
	ALLOC_HARDER
Message-ID: <20091027151904.GH8900@csn.ul.ie>
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On Fri, Oct 23, 2009 at 10:03:05PM -0400, Christoph Lameter wrote:
> There are now rt dependencies in the page allocator that screw things up?
> 

The rt logic was present before.

> And an rt flag causes the page allocator to try harder meaning it adds
> latency.
> 

The harder term in the flag is a bit misleading. The effect of ALLOC_HARDER
is that the watermark is lower for the task. i.e. a rt task is less likely
to enter direct reclaim than normal tasks so it should have less latency.

> ?
> 
> 

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
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