From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932177Ab3AIWww (ORCPT ); Wed, 9 Jan 2013 17:52:52 -0500 Received: from mxout2.iskon.hr ([213.191.128.81]:41822 "EHLO mxout2.iskon.hr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758156Ab3AIWwv (ORCPT ); Wed, 9 Jan 2013 17:52:51 -0500 X-Remote-IP: 213.191.128.133 Date: Wed, 09 Jan 2013 23:52:47 +0100 From: Zlatko Calusic Organization: Iskon Internet d.d. User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Icedove/17.0 MIME-Version: 1.0 To: Andrew Morton CC: Mel Gorman , Hugh Dickins , Minchan Kim , linux-mm , Linux Kernel Mailing List References: <50EDE41C.7090107@iskon.hr> <20130109134816.db51a820.akpm@linux-foundation.org> In-Reply-To: <20130109134816.db51a820.akpm@linux-foundation.org> Message-ID: <50EDF4BF.7000108@iskon.hr> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [PATCH] mm: wait for congestion to clear on all zones X-Anti-Virus: Kaspersky Anti-Virus for Linux Mail Server 5.6.45/RELEASE, bases: 20130110 #9042073, check: 20130109 clean X-SpamTest-Envelope-From: zlatko.calusic@iskon.hr X-SpamTest-Group-ID: 00000000 X-SpamTest-Info: Profiles 41238 [Jan 10 2013] X-SpamTest-Method: none X-SpamTest-Rate: 0 X-SpamTest-SPF: none X-SpamTest-Status: Not detected X-SpamTest-Status-Extended: not_detected X-SpamTest-Version: SMTP-Filter Version 3.0.0 [0284], KAS30/Release Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09.01.2013 22:48, Andrew Morton wrote: > On Wed, 09 Jan 2013 22:41:48 +0100 > Zlatko Calusic wrote: > >> Currently we take a short nap (HZ/10) and wait for congestion to clear >> before taking another pass with lower priority in balance_pgdat(). But >> we do that only for the highest zone that we encounter is unbalanced >> and congested. >> >> This patch changes that to wait on all congested zones in a single >> pass in the hope that it will save us some scanning that way. Also we >> take a nap as soon as congested zone is encountered and sc.priority < >> DEF_PRIORITY - 2 (aka kswapd in trouble). >> >> ... >> >> The patch is against the mm tree. Make sure that >> mm-avoid-calling-pgdat_balanced-needlessly.patch is applied first (not >> yet in the mmotm tree). Tested on half a dozen systems with different >> workloads for the last few days, working really well! > > But what are the user-observable effcets of this change? Less kernel > CPU consumption, presumably? Did you quantify it? > And I forgot to answer all the questions... :( Actually, I did record kswapd CPU usage after 5 days of uptime and I intend to compare it with the new data (after few more days pass). I expect maybe slightly better results. But, I think it's obvious from my first reply that my primary goal with this patch is correctness, not optimization. So, I won't be dissapointed a little bit if kswapd CPU usage stays the same, so long as the memory utilization remains this smooth. ;) -- Zlatko