Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935895AbXHIBOB (ORCPT ); Wed, 8 Aug 2007 21:14:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756197AbXHIBNu (ORCPT ); Wed, 8 Aug 2007 21:13:50 -0400 Received: from mailhub2.otago.ac.nz ([139.80.64.247]:59245 "EHLO mailhub2.otago.ac.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751610AbXHIBNt (ORCPT ); Wed, 8 Aug 2007 21:13:49 -0400 X-Greylist: delayed 922 seconds by postgrey-1.27 at vger.kernel.org; Wed, 08 Aug 2007 21:13:49 EDT Message-ID: <46BA6667.1070205@maths.otago.ac.nz> Date: Thu, 09 Aug 2007 12:57:11 +1200 From: Greg Trounson User-Agent: Thunderbird 2.0.0.5 (X11/20070719) MIME-Version: 1.0 To: Ingo Molnar CC: Linux Kernel Mailing List Subject: Re: [PATCH 00/23] per device dirty throttling -v8 References: <20070804103347.GA1956@elte.hu> <20070804163733.GA31001@elte.hu> <46B4C0A8.1000902@garzik.org> <20070804191205.GA24723@lazybastard.org> <20070804192130.GA25346@elte.hu> <20070804211156.5f600d80@the-village.bc.nu> <20070804202830.GA4538@elte.hu> <20070804224834.5187f9b7@the-village.bc.nu> <20070805071320.GC515@elte.hu> In-Reply-To: <20070805071320.GC515@elte.hu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1868 Lines: 40 Ingo Molnar wrote: > * Alan Cox wrote: > >>>> People just need to know about the performance differences - very >>>> few realise its more than a fraction of a percent. I'm sure Gentoo >>>> will use relatime the moment anyone knows its > 5% 8) >>> noatime,nodiratime gave 50% of wall-clock kernel rpm build >>> performance improvement for Dave Jones, on a beefy box. Unless i >>> misunderstood what you meant under 'fraction of a percent' your >>> numbers are _WAY_ off. >> What numbers - I didn't quote any performance numbers ? > > ok, i misunderstood your "very few realise its more than a fraction of a > percent" sentence, i thought you were saying it's a fraction of a > percent. > > Measurements show that noatime helps 20-30% on regular desktop > workloads, easily 50% for kernel builds and much more than that (in > excess of 100%) for file-read-intense workloads. We cannot just walk > past such a _huge_ performance impact so easily without even reacting to > the performance arguments, and i'm happy Ubuntu picked up > noatime,nodiratime and is whipping up the floor with Fedora on the > desktop. > Sorry I'm just not seeing those gains here. With my filesystems mounted with atime defaults the Quake sources build in 1m28.856s. A test with ls -ltu verifies that atime is working as expected. When I remount my filesystems with: mount [fs] -o remount,noatime,nodiratime I get a compile time of 1m23.368s, a mere 6% improvement. This is on a dual-core Athlon 4200+ box running 2.6.21, so I would have thought this to be close to a best-case file I/O test. Greg - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/