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 B0DD19DC800 for ; Wed, 11 Jan 2006 02:03:57 -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 97787-01 for ; Wed, 11 Jan 2006 02:03:56 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from smtpauth07.mail.atl.earthlink.net (smtpauth07.mail.atl.earthlink.net [209.86.89.67]) by postgresql.org (Postfix) with ESMTP id 9197F9DC801 for ; Wed, 11 Jan 2006 02:03:55 -0400 (AST) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=SK94i2hlZY1X6eqxcidqObTVtBaE6rCA8k7hY4VrVie/4SLprslNbaRtYFb4tTm0; h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; Received: from [70.22.244.95] (helo=ron-6d52adff2a6.earthlink.net) by smtpauth07.mail.atl.earthlink.net with asmtp (Exim 4.34) id 1EwZ5N-0007vM-1N; Wed, 11 Jan 2006 01:03:53 -0500 Message-Id: <7.0.1.0.2.20060111005534.0378a630@earthlink.net> X-Mailer: QUALCOMM Windows Eudora Version 7.0.1.0 Date: Wed, 11 Jan 2006 01:03:48 -0500 To: Mark Lewis ,pgsql-performance@postgresql.org From: Ron Subject: Re: help tuning queries on large database In-Reply-To: <1136939286.22590.27.camel@archimedes> References: <7.0.1.0.2.20060108160633.026bd358@earthlink.net> <1136939286.22590.27.camel@archimedes> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-ELNK-Trace: acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bcfe12da2425cfba20cce11acfa72a174a350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 70.22.244.95 X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.421 required=5 tests=[AWL=-0.058, DNS_FROM_RFC_ABUSE=0.479] X-Spam-Score: 0.421 X-Spam-Level: X-Archive-Number: 200601/101 X-Sequence-Number: 16579 At 07:28 PM 1/10/2006, Mark Lewis wrote: >Ron, > >A few days back you mentioned: > > > Upgrade your kernel to at least 2.6.12 > > There's a known issue with earlier versions of the 2.6.x kernel and > > 64b CPUs like the Opteron. See kernel.org for details. > > > >I did some searching and couldn't find any obvious mention of this issue >(I gave up after searching through the first few hundred instances of >"64" in the 2.6.12 changelog). > >Would you mind being a little more specific about which issue you're >talking about? We're about to deploy some new 16GB RAM Opteron DB >servers and I'd like to check and make sure RH backported whatever the >fix was to their current RHEL4 kernel. There are 3 issues I know about in general: 1= As Peter Royal noted on this list, pre 12 versions of 2.6.x have problems with RAM of >= 4GB. 2= Pre 12 versions on 2.6.x when running A64 or Xeon 64b SMP seem to be susceptible to "context switch storms". 3= Physical and memory IO is considerably improved in the later versions of 2.6.x compared to 2.6.11 or earlier. Talk to a real Linux kernel guru (I am not) for details and specifics. Ron