Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1U7wYD-0002Tx-2c for pgsql-performance@arkaria.postgresql.org; Tue, 19 Feb 2013 23:24:42 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.72) (envelope-from ) id 1U7wYA-0001AT-Vp for pgsql-performance@arkaria.postgresql.org; Tue, 19 Feb 2013 23:24:39 +0000 Received: from makus.postgresql.org ([2001:4800:7903:4::125]) by malur.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1U7wY9-0001AN-Rm for pgsql-performance@postgresql.org; Tue, 19 Feb 2013 23:24:38 +0000 Received: from outmail149092.authsmtp.com ([62.13.149.92]) by makus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1U7wY8-0001mE-9R for pgsql-performance@postgresql.org; Tue, 19 Feb 2013 23:24:37 +0000 Received: from mail-c232.authsmtp.com (mail-c232.authsmtp.com [62.13.128.232]) by punt10.authsmtp.com (8.14.2/8.14.2/Kp) with ESMTP id r1JNOYoW087929 for ; Tue, 19 Feb 2013 23:24:34 GMT Received: from [172.47.23.103] (70-36-143-10.dsl.dynamic.sonic.net [70.36.143.10]) (authenticated bits=0) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id r1JNOWMn066097 for ; Tue, 19 Feb 2013 23:24:33 GMT Message-ID: <512409AF.8010308@agliodbs.com> Date: Tue, 19 Feb 2013 15:24:31 -0800 From: Josh Berkus Organization: PostgreSQL Experts Inc. User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: pgsql-performance@postgresql.org Subject: Re: High CPU usage / load average after upgrading to Ubuntu 12.04 References: <60B572D9298D944580F7D51195DD30804357FA4ABF@VMBX125.ihostexchange.net> <60B572D9298D944580F7D51195DD30804357FA4B60@VMBX125.ihostexchange.net> <60B572D9298D944580F7D51195DD30804357FA4C11@VMBX125.ihostexchange.net> <511BE879.8080706@agliodbs.com> <511C2F10.3080409@agliodbs.com> <60B572D9298D944580F7D51195DD30804357FA4DE2@VMBX125.ihostexchange.net> <511D2F11.6040706@agliodbs.com> <60B572D9298D944580F7D51195DD308043580CAA0B@VMBX125.ihostexchange.net> <511D79FE.7060705@agliodbs.com> <60B572D9298D944580F7D51195DD308043580CAA87@VMBX125.ihostexchange.net> <511E7DC0.4090506@agliodbs.com> <5122C507.7060303@agliodbs.com> <5122C9D9.9040909@agliodb s.com> <5122FF50.8030903@catalyst.net.nz> <5123BB94.7030603@agliodb! s.com> In-Reply-To: <5123BB94.7030603@agliodbs.com> X-Enigmail-Version: 1.5 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Server-Quench: 84b5b457-7aeb-11e2-b10b-0025903375e2 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCdyZgscClZXSx8a IioLCC5HRQ8+YBZL BAkbIhBDJB8RWB5f NVxfJ1xYPXUEQkpF VCReGBUITgIzDi10 YhUnOFdCYEpPXBVo U0JLRlhRF0tvAQIC AAAfVhpsdgVZen1v ZQggXwolIyMHK0Z7 RE5dEiMEYGFmJmgb AkUKcwZTbQQbK01Y a1EqVm5fYGVVe3pg RVJiZ2tqYmhScjJv T1NFHmo/e2gsJBsJ DzADEjVnNnU4Dzgo JhMrYhlUGEEYPg07 L1Y7UF0VexYcFgBE V1xVDzVQK1gHSGI3 CktnV1MYDCA/CX4G REV0SgAA X-Authentic-SMTP: 61633136333939.1019:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 70.36.143.10/23 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Pg-Spam-Score: -2.6 (--) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-performance Precedence: bulk Sender: pgsql-performance-owner@postgresql.org On 02/19/2013 09:51 AM, Josh Berkus wrote: > On 02/18/2013 08:28 PM, Mark Kirkwood wrote: >> Might be worth looking at your vm.dirty_ratio, vm.dirty_background_ratio >> and friends settings. We managed to choke up a system with 16x SSD by >> leaving them at their defaults... > > Yeah? Any settings you'd recommend specifically? What did you use on > the SSD system? > NM, I tested lowering dirty_background_ratio, and it didn't help, because checkpoints are kicking in before pdflush ever gets there. So the issue seems to be that if you have this combination of factors: 1. large RAM 2. many/fast CPUs 3. a database which fits in RAM but is larger than the RAID controller's WB cache 4. pg_xlog on the same volume as pgdata ... then you'll see checkpoint "stalls" and spread checkpoint will actually make them worse by making the stalls longer. Moving pg_xlog to a separate partition makes this better. Making bgwriter more aggressive helps a bit more on top of that. -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance