Received: from localhost (unknown [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id 3E74A9FA4C7 for ; Fri, 21 Sep 2007 07:08:54 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 76621-01 for ; Fri, 21 Sep 2007 07:08:06 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from mail3.ecircle.de (mail3.ecircle.de [195.140.186.206]) by postgresql.org (Postfix) with ESMTP id 773979FA481 for ; Fri, 21 Sep 2007 07:08:10 -0300 (ADT) Received: from einstein.muc.ecircle.de (einstein.muc.ecircle.de [192.168.1.7]) by mail3.ecircle.de (READY) with ESMTP id E0D1711C0B2; Fri, 21 Sep 2007 12:08:08 +0200 (CEST) Received: from [192.168.1.91] ([192.168.1.91]) by einstein.muc.ecircle.de with Microsoft SMTPSVC(6.0.3790.1830); Fri, 21 Sep 2007 12:08:08 +0200 Subject: Re: Linux mis-reporting memory From: Csaba Nagy To: Gregory Stark Cc: Decibel! , pgsql-performance@postgresql.org In-Reply-To: <87r6ksuzf8.fsf@oxford.xeocode.com> References: <20070920230400.GM95343@decibel.org> <16213.1190329934@sss.pgh.pa.us> <87r6ksa1jb.fsf@oxford.xeocode.com> <1190363401.4661.116.camel@PCD12478> <87r6ksuzf8.fsf@oxford.xeocode.com> Content-Type: text/plain Date: Fri, 21 Sep 2007 12:08:45 +0200 Message-Id: <1190369325.4661.178.camel@PCD12478> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 21 Sep 2007 10:08:08.0706 (UTC) FILETIME=[4F4AEE20:01C7FC37] X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200709/353 X-Sequence-Number: 26898 On Fri, 2007-09-21 at 10:43 +0100, Gregory Stark wrote: > The other possibility is that Postgres just hasn't even touched a large part > of its shared buffers. > But then how do you explain the example I gave, with a 5.5GB table seq-scanned 3 times, shared buffers set to 12 GB, and top still showing almost 100% memory as cached and no SWAP "used" ? In this case you can't say postgres didn't touch it's shared buffers - or a sequential scan won't use the shared buffers ? Cheers, Csaba.