Received: from makus.postgresql.org (makus.postgresql.org [98.129.198.125]) by mail.postgresql.org (Postfix) with ESMTP id 306B61648186 for ; Fri, 30 Mar 2012 21:51:51 -0300 (ADT) Received: from smtp.01.com ([199.36.142.181]) by makus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1SDmXj-0003CP-1u for pgsql-performance@postgresql.org; Sat, 31 Mar 2012 00:51:50 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp-out-1.01.com (Postfix) with ESMTP id 5A6B33F572E for ; Fri, 30 Mar 2012 19:51:34 -0500 (CDT) X-Virus-Scanned: amavisd-new at smtp-out-1.01.com Received: from smtp.01.com ([127.0.0.1]) by localhost (smtp-out-1.01.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id scsc63RGNq7Z for ; Fri, 30 Mar 2012 19:51:34 -0500 (CDT) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp-out-1.01.com (Postfix) with ESMTP id 3BA023F5779 for ; Fri, 30 Mar 2012 19:51:34 -0500 (CDT) Received: from Sidney-Stratton.local (70-36-143-92.dsl.dynamic.sonic.net [70.36.143.92]) by smtp-out-1.01.com (Postfix) with ESMTPSA id 0DA613F572E for ; Fri, 30 Mar 2012 19:51:33 -0500 (CDT) Message-ID: <4F765515.3050203@agliodbs.com> Date: Fri, 30 Mar 2012 17:51:33 -0700 From: Josh Berkus Organization: PostgreSQL Experts Inc. User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2 MIME-Version: 1.0 To: pgsql-performance@postgresql.org Subject: Re: Linux machine aggressively clearing cache References: <807948699.229132.1332959858793.JavaMail.root@mail-1.01.com> In-Reply-To: <807948699.229132.1332959858793.JavaMail.root@mail-1.01.com> X-Enigmail-Version: 1.4 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: -1.9 (-) X-Archive-Number: 201203/191 X-Sequence-Number: 46641 >> Read cache of course does not need to be flushed and can simply be >> dumped when the memory is needed, and so Linux will keep more or >> less unlimited amounts of read cache until it needs the memory for >> something else .... > > Right, that's the normal behavior. Except not on this machine. So this turned out to be a Linux kernel issue. Will document it on www.databasesoup.com. -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com