Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id A87C32E2D5B for ; Wed, 26 Dec 2007 07:25:51 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 26121-08 for ; Wed, 26 Dec 2007 07:25:46 -0400 (AST) Received: from outmail137066.authsmtp.net (outmail137066.authsmtp.net [62.13.137.66]) by postgresql.org (Postfix) with ESMTP id 4DC0E2E09A2 for ; Wed, 26 Dec 2007 07:20:46 -0400 (AST) Received: from outmail128183.authsmtp.com (outmail128183.authsmtp.com [62.13.128.183]) by punt4.authsmtp.com (8.14.1/8.14.1/Kp) with ESMTP id lBQBKb0Z058754; Wed, 26 Dec 2007 11:20:37 GMT Received: from [192.168.0.3] (85-211-72-213.dyn.gotadsl.co.uk [85.211.72.213]) (authenticated bits=0) by mail.authsmtp.com (8.13.8/8.13.8/Kp) with ESMTP id lBQBKaUO017481; Wed, 26 Dec 2007 11:20:36 GMT Subject: Re: More shared buffers causes lower performances From: Simon Riggs To: Guillaume Smet Cc: pgsql-performance , Stefan Kaltenbrunner In-Reply-To: <1d4e0c10712251606q6f9503deye3da4b68c51bf5e@mail.gmail.com> References: <1d4e0c10712251606q6f9503deye3da4b68c51bf5e@mail.gmail.com> Content-Type: text/plain Date: Wed, 26 Dec 2007 11:21:05 +0000 Message-Id: <1198668065.4221.288.camel@ebony.site> Mime-Version: 1.0 X-Mailer: Evolution 2.8.2 Content-Transfer-Encoding: 7bit X-Server-Quench: 951f508f-b3a4-11dc-814e-001185d377ca X-AuthRoute: OCdxZQATClZOTQEd DAteCiNZVAwpPBRK HVkIKg5MJUcNSQVJ NksadRtFagNbaVxS HGQLW1NEUVx7W2N/ aA0fZQBDYEtPQQJo TkpIQU1QERpoT0Bz Z2xlA3wNdwRBfHZx K0diWHYVVUF7I0N9 ShhJR25XYXphaTRM TUhZc1ZJcANLfxdA PlN4UyBcLwdSbGoL JyIJERcLGAAXDSNP T0kWLVsITEpDFCMy SR0YBn0kFFAeSj57 Kxs5J0RUBEsLPEIo NFInUl8DW3Vp X-Authentic-SMTP: 61633235383639.squirrel.dmpriest.net.uk:787/Kp X-Report-SPAM: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-Virus-Status: No virus detected - but ensure you scan with your own anti-virus system! X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200712/354 X-Sequence-Number: 28170 On Wed, 2007-12-26 at 01:06 +0100, Guillaume Smet wrote: > I lowered the number of concurrent clients to 50 because 100 is quite > high and I obtain the same sort of results: > shared_buffers=32MB: 1869 tps > shared_buffers=64MB: 1844 tps > shared_buffers=512MB: 1676 tps > shared_buffers=1024MB: 1559 tps Can you try with bgwriter_lru_maxpages = 0 So we can see if the bgwriter has any hand in this? -- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com