Received: from localhost (unknown [200.46.208.211]) by mail.postgresql.org (Postfix) with ESMTP id C72F56352BB for ; Tue, 17 Mar 2009 01:19:32 -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 66613-04 for ; Tue, 17 Mar 2009 01:19:29 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from westnet.com (westnet.com [216.187.52.2]) by mail.postgresql.org (Postfix) with ESMTP id 7C97763515B for ; Tue, 17 Mar 2009 01:19:30 -0300 (ADT) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id n2H4JQZQ007486; Tue, 17 Mar 2009 00:19:26 -0400 (EDT) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id n2H4JP4d007483; Tue, 17 Mar 2009 00:19:25 -0400 (EDT) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Tue, 17 Mar 2009 00:19:25 -0400 (EDT) From: Greg Smith X-X-Sender: gsmith@westnet.com To: Gregory Stark cc: Joe Uhl , pgsql-performance@postgresql.org Subject: Re: High CPU Utilization In-Reply-To: <87d4ch0z4z.fsf@oxford.xeocode.com> Message-ID: References: <8609D1C0-3ECD-4A4F-B9C6-1FC8496EDC7A@gmail.com> <200903161252.22202@hal.medialogik.com> <5F9840B1-D080-4F3A-81D4-57E8F1DB0955@gmail.com> <87d4ch0z4z.fsf@oxford.xeocode.com> User-Agent: Alpine 2.01 (GSO 1184 2008-12-16) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed 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: 200903/227 X-Sequence-Number: 33149 On Tue, 17 Mar 2009, Gregory Stark wrote: > Hm, well the tests I ran for posix_fadvise were actually on a Perc5 -- though > who knows if it was the same under the hood -- and I saw better performance > than this. I saw about 4MB/s for a single drive and up to about 35MB/s for 15 > drives. However this was using linux md raid-0, not hardware raid. Right, it's the hardware RAID on the Perc5 I think people mainly complain about. If you use it in JBOD mode and let the higher performance CPU in your main system drive the RAID functions it's not so bad. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD