From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtprelay0132.hostedemail.com ([216.40.44.132]:37610 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757552Ab3JJVSG (ORCPT ); Thu, 10 Oct 2013 17:18:06 -0400 Message-ID: <52571992.3020607@nellans.org> Date: Thu, 10 Oct 2013 16:18:10 -0500 From: David Nellans MIME-Version: 1.0 Subject: Re: IO scheduler References: <52571453.4050101@nellans.org> <5257158A.2050707@enovance.com> In-Reply-To: <5257158A.2050707@enovance.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: Erwan Velu Cc: "Brian L." , "fio@vger.kernel.org" > That's a little bit extreme but it insures the same OS & environment to > be used over & over making all my tests much more comparable over time. > Thats a really good point - I guess I should also be a little more specific about how we achieved tight reproducibility. We used dedicated machines with identical components, a fixed point within an OS distribution, a known bios revision/settings, and disabled any/all frequency/power scaling. So while we ran the machines without any special tricks, the machine configurations and OS were very extremely locked down and identical except for a hostname. Anytime we changed anything within the cluster configuration we quantified the change before rolling it out cluster wide since on more than one occasion we discovered even things like bios revisions would substantially affect PCIe based testing.