From owner-freebsd-questions@FreeBSD.ORG Tue Apr 25 13:39:32 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 59C1C16A401 for ; Tue, 25 Apr 2006 13:39:32 +0000 (UTC) (envelope-from derek@computinginnovations.com) Received: from betty.computinginnovations.com (dsl081-142-072.chi1.dsl.speakeasy.net [64.81.142.72]) by mx1.FreeBSD.org (Postfix) with ESMTP id 956AC43D46 for ; Tue, 25 Apr 2006 13:39:26 +0000 (GMT) (envelope-from derek@computinginnovations.com) Received: from p17.computinginnovations.com (dhcp-10-20-30-100.computinginnovations.com [10.20.30.100]) (authenticated bits=0) by betty.computinginnovations.com (8.13.5/8.12.11) with ESMTP id k3PDd21W003657; Tue, 25 Apr 2006 08:39:03 -0500 (CDT) Message-Id: <6.0.0.22.2.20060425083303.0293a8a8@mail.computinginnovations.com> X-Sender: derek@mail.computinginnovations.com X-Mailer: QUALCOMM Windows Eudora Version 6.0.0.22 Date: Tue, 25 Apr 2006 08:38:55 -0500 To: Bill Moran From: Derek Ragona In-Reply-To: <20060425092526.6fe5efa6.wmoran@collaborativefusion.com> References: <20060424154617.9dc28c94.wmoran@potentialtech.com> <6.0.0.22.2.20060424175443.02927f48@mail.computinginnovations.com> <20060425084752.2453c0f1.wmoran@collaborativefusion.com> <6.0.0.22.2.20060425075227.028aea10@mail.computinginnovations.com> <20060425092526.6fe5efa6.wmoran@collaborativefusion.com> Mime-Version: 1.0 X-ComputingInnovations-MailScanner-Information: Please contact the ISP for more information X-ComputingInnovations-MailScanner: Found to be clean X-ComputingInnovations-MailScanner-From: derek@computinginnovations.com X-Spam-Status: No Content-Type: text/plain; charset="us-ascii"; format=flowed X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-questions@freebsd.org Subject: Re: Purchasing the correct hardware: dual-core intel? Big cache? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 25 Apr 2006 13:39:32 -0000 Bill, Never assume . . . Depending on where you got the PostgreSQL, was it in binary form or source. Most binarys are NOT optimized for higher end, more current processors, rather they are optimized for the most common family of CPU's. But if your database application is really CPU bound, I would look at the data model and how your application is accessing and using the data. RDBMS's can be very effiicent, or terribly inefficient. In the worst case you can cause an RDBMS to serially go through every record searching for data or doing a calculation. While a bigger cache may help, as may dual core CPU's, or faster CPU's. In the end, you may only see marginal improvement if the application or database is really where you need to tune things. -Derek At 08:25 AM 4/25/2006, Bill Moran wrote: >On Tue, 25 Apr 2006 07:56:03 -0500 >Derek Ragona wrote: > > > Yes, dual core is on average 20% faster than hyperthreaded CPU's. But > that > > is general benchmark. The range of performance difference is 10% - 30% > > depending on the application mix. > >Thanks. > > > If you use well optimized applications, you see the larger performance > > gain. Poor optimization causes a CPU to chug along, flushing the CPU > cache > > often, and slowing things down considerably. > >I know. That's why I'm so desperately trying to find a way to determine >how often the cache is being invalidated - so I can determine whether >larger cache sizes (such as 8M) are worthwhile. > >The database server is PostgreSQL. If we find optimization problems >with it, we'll definitely work with the PostgreSQL folks to get those >problems addressed, but I'm not expecting a lot of poorly-written code >in something as mature as PostgreSQL. So, making a (reasonable) >assumption that PostgreSQL is well-optimized, I need a way to tell if >adding another 6M of cache will improve performance, _before_ we pay >for it. > >That's my question. > >-- >Bill Moran >Collaborative Fusion Inc. > >**************************************************************** >IMPORTANT: This message contains confidential information and is >intended only for the individual named. If the reader of this >message is not an intended recipient (or the individual >responsible for the delivery of this message to an intended >recipient), please be advised that any re-use, dissemination, >distribution or copying of this message is prohibited. 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