Received: from maia.hub.org (maia-5.hub.org [200.46.204.29]) by mail.postgresql.org (Postfix) with ESMTP id DE0531337BCD for ; Fri, 4 Mar 2011 14:03:48 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.29]) (amavisd-maia, port 10024) with ESMTP id 68571-08 for ; Fri, 4 Mar 2011 18:03:38 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mail1.databill.com (mail1.databill.com [69.16.152.116]) by mail.postgresql.org (Postfix) with ESMTP id 657E71337BC9 for ; Fri, 4 Mar 2011 14:03:38 -0400 (AST) Received: from [10.0.0.15] ([::ffff:10.0.0.15]) (AUTH: LOGIN wayne@databill.com) by mail1.databill.com with esmtp; Fri, 04 Mar 2011 11:03:36 -0700 id 016A01D6.4D712978.0000276A Message-ID: <4D712978.60504@databill.com> Date: Fri, 04 Mar 2011 11:03:36 -0700 From: Wayne Conrad User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.15) Gecko/20101030 Icedove/3.0.10 MIME-Version: 1.0 To: pgsql-performance@postgresql.org Subject: Re: Linux I/O schedulers - CFQ & random seeks References: <536110.72154.qm@web26008.mail.ukl.yahoo.com> In-Reply-To: <536110.72154.qm@web26008.mail.ukl.yahoo.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-10 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201103/52 X-Sequence-Number: 42731 On 03/04/11 10:34, Glyn Astill wrote: > I'm wondering (and this may be a can of worms) what peoples opinions are on these schedulers? When testing our new DB box just last month, we saw a big improvement in bonnie++ random I/O rates when using the noop scheduler instead of cfq (or any other). We've got RAID 10/12 on a 3ware card w/ battery-backed cache; 7200rpm drives. Our file system is XFS with noatime,nobarrier,logbufs=8,logbsize=256k. How much is "big?" I can't find my notes for it, but I recall that the difference was large enough to surprise us. We're running with noop in production right now. No complaints.