X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id 6A7B49DCC46 for ; Thu, 16 Mar 2006 10:30:25 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 21190-03 for ; Thu, 16 Mar 2006 10:30:29 -0400 (AST) Received: from svr4.postgresql.org (svr4.postgresql.org [66.98.251.159]) by postgresql.org (Postfix) with ESMTP id 1F0769DCC19 for ; Thu, 16 Mar 2006 10:30:23 -0400 (AST) Received: from is.rice.edu (is.rice.edu [128.42.42.24]) by svr4.postgresql.org (Postfix) with ESMTP id 38E485AF085 for ; Thu, 16 Mar 2006 14:30:27 +0000 (GMT) Received: from scan2.mail.rice.edu (scan2.mail.rice.edu [128.42.59.161]) by is.rice.edu (Postfix) with ESMTP id C98174187A; Thu, 16 Mar 2006 08:30:24 -0600 (CST) Received: from is.rice.edu ([128.42.42.24]) by scan2.mail.rice.edu (scan2.mail.rice.edu [128.42.59.161]) (amavisd-new, port 10024) with ESMTP id 28823-01; Thu, 16 Mar 2006 08:30:21 -0600 (CST) Received: by is.rice.edu (Postfix, from userid 18612) id 219A5418A2; Thu, 16 Mar 2006 08:30:21 -0600 (CST) Date: Thu, 16 Mar 2006 08:30:20 -0600 From: Kenneth Marshall To: Guillaume Smet Cc: pgsql-performance@postgresql.org Subject: Re: PostgreSQL and Xeon MP Message-ID: <20060316143020.GW22830@it.is.rice.edu> References: <1d4e0c10603160245n55128e86t35431a339afcf8cc@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1d4e0c10603160245n55128e86t35431a339afcf8cc@mail.gmail.com> User-Agent: Mutt/1.4.2i X-Virus-Scanned: by amavis-2.2.1 at scan2.mail.rice.edu X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.08 required=5 tests=[AWL=0.080] X-Spam-Score: 0.08 X-Spam-Level: X-Archive-Number: 200603/310 X-Sequence-Number: 17747 On Thu, Mar 16, 2006 at 11:45:12AM +0100, Guillaume Smet wrote: > Hello, > > We are experiencing performances problem with a quad Xeon MP and > PostgreSQL 7.4 for a year now. Our context switch rate is not so high > but the load of the server is blocked to 4 even on very high load and > we have 60% cpu idle even in this case. Our database fits in RAM and > we don't have any IO problem. I saw this post from Tom Lane > http://archives.postgresql.org/pgsql-performance/2004-04/msg00249.php > and several other references to problem with Xeon MP and I suspect our > problems are related to this. > We tried to put our production load on a dual standard Xeon on monday > and it performs far better with the same configuration parameters. > > I know that work has been done by Tom for PostgreSQL 8.1 on > multiprocessor support but I didn't find any information on if it > solves the problem with Xeon MP or not. > > My question is should we expect a resolution of our problem by > switching to 8.1 or will we still have problems and should we consider > a hardware change? We will try to upgrade next tuesday so we will have > the real answer soon but if anyone has any experience or information > on this, he will be very welcome. > > Thanks for your help. > > -- > Guillaume > Guillaume, We had a similar problem with poor performance on a Xeon DP and PostgreSQL 7.4.x. 8.0 came out in time for preliminary testing but it did not solve the problem and our production systems went live using a different database product. We are currently testing against 8.1.x and the seemingly bizarre lack of performance is gone. I would suspect that a quad-processor box would have the same issue. I would definitely recommend giving 8.1 a try. Ken