Received: from localhost (unknown [200.46.208.211]) by mail.postgresql.org (Postfix) with ESMTP id 2665D633EA4 for ; Wed, 11 Mar 2009 16:32:44 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.208.211]) (amavisd-maia, port 10024) with ESMTP id 72222-06 for ; Wed, 11 Mar 2009 16:32:35 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from depesz.com (depesz.com [78.46.78.198]) by mail.postgresql.org (Postfix) with ESMTP id 200A0633670 for ; Wed, 11 Mar 2009 16:32:36 -0300 (ADT) Received: from depesz by depesz.com with local (Exim 4.69) (envelope-from ) id 1LhUAF-0005SD-EM; Wed, 11 Mar 2009 20:32:27 +0100 Date: Wed, 11 Mar 2009 20:32:27 +0100 From: hubert depesz lubaczewski To: Scott Carey Cc: Andrej , Grzegorz =?utf-8?Q?Ja=C5=9Bkiewicz?= , Jeff , "pgsql-performance@postgresql.org" Subject: Re: random_page_cost vs ssd? Message-ID: <20090311193227.GA19182@depesz.com> Reply-To: depesz@depesz.com References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200903/100 X-Sequence-Number: 33022 On Wed, Mar 11, 2009 at 12:28:56PM -0700, Scott Carey wrote: > Google > “linux drop_caches” first result: > http://www.linuxinsight.com/proc_sys_vm_drop_caches.html > To be sure a test is going to disk and not file system cache for everything in linux, run: > ‘sync; cat 3 > /proc/sys/vm/drop_caches’ well. the url you showed tells to do: echo 3 > ... cat 3 is "slightly" different. Best regards, depesz -- Linkedin: http://www.linkedin.com/in/depesz / blog: http://www.depesz.com/ jid/gtalk: depesz@depesz.com / aim:depeszhdl / skype:depesz_hdl / gg:6749007