Received: from maia.hub.org (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id 5D13D634C74 for ; Wed, 10 Feb 2010 02:37:48 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 57043-01 for ; Wed, 10 Feb 2010 06:37:37 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.126.171]) by mail.postgresql.org (Postfix) with ESMTP id 6365E635557 for ; Wed, 10 Feb 2010 02:37:25 -0400 (AST) Received: from [192.168.0.105] (pool-96-244-14-10.bltmmd.fios.verizon.net [96.244.14.10]) by mrelayeu.kundenserver.de (node=mreu2) with ESMTP (Nemesis) id 0MMrhT-1NdiLl0rPz-0089LQ; Wed, 10 Feb 2010 07:37:08 +0100 Message-ID: <4B725410.5010000@2ndquadrant.com> Date: Wed, 10 Feb 2010 01:37:04 -0500 From: Greg Smith User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: Jeff CC: david@lang.hm, Hannu Krosing , Kevin Grittner , pgsql-performance@postgresql.org, Albe Laurenz Subject: Re: Linux I/O tuning: CFQ vs. deadline References: <4B6FDD26.9010106@2ndquadrant.com> <4B6FD868020000250002F084@gw.wicourts.gov> <4B702E05.1000708@2ndquadrant.com> <1265652529.2153.13.camel@hvost> <4B70E18D.2040709@2ndquadrant.com> <39DDB34B-C375-46ED-83D2-688A32188100@torgo.978.org> In-Reply-To: <39DDB34B-C375-46ED-83D2-688A32188100@torgo.978.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V01U2FsdGVkX1+bZMP2ReRQzLisiQT6eSIMwEOc4VRpEcwHI4j O9+DXmm3tHQlK3enqvLQsWovv5Vi0yhQhu8Ur/K2HqN+Pl25nL UjJCy2pu+tJbHz4yFF7cKsMzRWhvrBk X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-2.599 tagged_above=-10 required=5 tests=BAYES_00=-2.599 X-Spam-Level: X-Archive-Number: 201002/151 X-Sequence-Number: 37572 Jeff wrote: > I'd done some testing a while ago on the schedulers and at the time > deadline or noop smashed cfq. Now, it is 100% possible since then > that they've made vast improvements to cfq and or the VM to get better > or similar performance. I recall a vintage of 2.6 where they severely > messed up the VM. Glad I didn't upgrade to that one :) > > Here's the old post: > http://archives.postgresql.org/pgsql-performance/2008-04/msg00155.php pgiosim doesn't really mix writes into there though, does it? The mixed read/write situations are the ones where the scheduler stuff gets messy. -- Greg Smith 2ndQuadrant Baltimore, MD PostgreSQL Training, Services and Support greg@2ndQuadrant.com www.2ndQuadrant.com