X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 77082D6E94 for ; Sun, 20 Nov 2005 17:48:51 -0400 (AST) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 52416-01 for ; Sun, 20 Nov 2005 21:48:52 +0000 (GMT) X-Greylist: from auto-whitelisted by SQLgrey- Received: from moonunit2.moonview.localnet (wsip-68-15-5-150.sd.sd.cox.net [68.15.5.150]) by svr1.postgresql.org (Postfix) with ESMTP id 8C16AD6833 for ; Sun, 20 Nov 2005 17:48:48 -0400 (AST) Received: from [192.168.0.3] (moonunit3.moonview.localnet [192.168.0.3]) by moonunit2.moonview.localnet (8.13.1/8.13.1) with ESMTP id jAKLvekp027710 for ; Sun, 20 Nov 2005 13:57:40 -0800 Message-ID: <4380EEA2.4010002@modgraph-usa.com> Date: Sun, 20 Nov 2005 13:46:10 -0800 From: "Craig A. James" User-Agent: Mozilla Thunderbird 1.0.6 (X11/20050716) X-Accept-Language: en-us, en MIME-Version: 1.0 CC: pgsql-performance@postgresql.org Subject: Hyperthreading slows processes? References: <1132136225.5711.4.camel@Panoramix> <437B9DA9.2030806@modgraph-usa.com> <20051117002344.GA55377@winnie.fuhr.org> <437CF055.6020602@modgraph-usa.com> <20051117232857.GA49910@winnie.fuhr.org> <437D3085.9040207@modgraph-usa.com> <20051118034631.GA70159@winnie.fuhr.org> <437F66CF.7080402@modgraph-usa.com> <20051119190304.GJ7330@mathom.us> In-Reply-To: <20051119190304.GJ7330@mathom.us> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.118 required=5 tests=[AWL=-0.071, MISSING_HEADERS=0.189] X-Spam-Score: 0.118 X-Spam-Level: X-Archive-Number: 200511/414 X-Sequence-Number: 15671 This article on ZDNet claims that hyperthreading can *hurt* performance, due to contention in the L1/L2 cache by a second process: http://news.zdnet.co.uk/0,39020330,39237341,00.htm Has anyone tested this on Postgres yet? (And based on a recent somewhat caustic thread about performance on this forum, I'm going to avoid speculation, and let those who actually *know* answer! ;-) Craig