From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752701Ab2KLNbo (ORCPT ); Mon, 12 Nov 2012 08:31:44 -0500 Received: from cantor2.suse.de ([195.135.220.15]:36316 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751545Ab2KLNbn (ORCPT ); Mon, 12 Nov 2012 08:31:43 -0500 Date: Mon, 12 Nov 2012 13:31:39 +0000 From: Mel Gorman To: Zdenek Kabelac Cc: Seth Jennings , Jiri Slaby , Valdis.Kletnieks@vt.edu, Jiri Slaby , linux-mm@kvack.org, LKML , Andrew Morton , Rik van Riel , Robert Jennings Subject: Re: kswapd0: excessive CPU usage Message-ID: <20121112133139.GU8218@suse.de> References: <20121015110937.GE29125@suse.de> <5093A3F4.8090108@redhat.com> <5093A631.5020209@suse.cz> <509422C3.1000803@suse.cz> <509C84ED.8090605@linux.vnet.ibm.com> <509CB9D1.6060704@redhat.com> <20121109090635.GG8218@suse.de> <509F6C2A.9060502@redhat.com> <20121112121956.GT8218@suse.de> <50A0F5F0.6090400@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <50A0F5F0.6090400@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 12, 2012 at 02:13:20PM +0100, Zdenek Kabelac wrote: > Dne 12.11.2012 13:19, Mel Gorman napsal(a): > >On Sun, Nov 11, 2012 at 10:13:14AM +0100, Zdenek Kabelac wrote: > >>Hmm, so it's just took longer to hit the problem and observe kswapd0 > >>spinning on my CPU again - it's not as endless like before - but > >>still it easily eats minutes - it helps to turn off Firefox or TB > >>(memory hungry apps) so kswapd0 stops soon - and restart those apps > >>again. > >>(And I still have like >1GB of cached memory) > >> > > > >I posted a "safe" patch that I believe explains why you are seeing what > >you are seeing. It does mean that there will still be some stalls due to > >THP because kswapd is not helping and it's avoiding the problem rather > >than trying to deal with it. > > > >Hence, I'm also going to post this patch even though I have not tested > >it myself. If you find it fixes the problem then it would be a > >preferable patch to the revert. It still is the case that the > >balance_pgdat() logic is in sort need of a rethink as it's pretty > >twisted right now. > > > > > Should I apply them all together for 3.7-rc5 ? > > 1) https://lkml.org/lkml/2012/11/5/308 > 2) https://lkml.org/lkml/2012/11/12/113 > 3) https://lkml.org/lkml/2012/11/12/151 > Not all together. Test either 1+2 or 1+3. 1+2 is the safer choice but does nothing about THP stalls. 1+3 is a riskier version but depends on me being correct on what the root cause of the problem you see it. If both 1+2 and 1+3 work for you, I'd choose 1+3 for merging. If you only have the time to test one combination then it would be preferred that you test the safe option of 1+2. Thanks. -- Mel Gorman SUSE Labs