Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753961AbZKDCIO (ORCPT ); Tue, 3 Nov 2009 21:08:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753480AbZKDCIN (ORCPT ); Tue, 3 Nov 2009 21:08:13 -0500 Received: from gir.skynet.ie ([193.1.99.77]:57751 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752572AbZKDCIN (ORCPT ); Tue, 3 Nov 2009 21:08:13 -0500 Date: Wed, 4 Nov 2009 02:08:15 +0000 From: Mel Gorman To: Frans Pop Cc: Andrew Morton , stable@kernel.org, linux-kernel@vger.kernel.org, "linux-mm@kvack.org" , Jiri Kosina , Sven Geggus , Karol Lewandowski , Tobias Oetiker , KOSAKI Motohiro , Pekka Enberg , Rik van Riel , Christoph Lameter , Stephan von Krawczynski , Kernel Testers List Subject: Re: [PATCH 3/3] vmscan: Force kswapd to take notice faster when high-order watermarks are being hit Message-ID: <20091104020815.GH22046@csn.ul.ie> References: <1256650833-15516-1-git-send-email-mel@csn.ul.ie> <200911032301.59662.elendil@planet.nl> <20091103220808.GF22046@csn.ul.ie> <200911040101.50194.elendil@planet.nl> <20091104011811.GG22046@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20091104011811.GG22046@csn.ul.ie> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1650 Lines: 40 On Wed, Nov 04, 2009 at 01:18:11AM +0000, Mel Gorman wrote: > > From vmstat for .31.1: > > kswapd_highorder_rewakeup 20 > > kswapd_slept_prematurely_fast 307 > > kswapd_slept_prematurely_slow 105 > > > > This is useful. > > The high premature_fast shows that after kswapd apparently finishes its work, > the high waterwater marks are being breached very quickly (the fast counter > being positive). The "slow" counter is even worse. Your machine is getting > from the high to low watermark quickly without kswapd noticing and processes > depending on the atomics are not waiting long enough. > Sorry, that should have been The premature_fast shows that after kswapd finishes its work, the low waterwater marks are being breached very quickly as kswapd is being rewoken up. The "slow" counter is slightly worse. Just after kswapd sleeps, the high watermark is being breached again. Either counter being positive implies that kswapd is having to do too much work while parallel allocators are chewing up the high-order pages quickly. The effect of the patch should still be to delay the rate high-order pages are consumed but it assumes there are enough high-order requests that can go to sleep. Mentioning sleep, I'm going to get some. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/