Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756646AbXHETLr (ORCPT ); Sun, 5 Aug 2007 15:11:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756634AbXHETL2 (ORCPT ); Sun, 5 Aug 2007 15:11:28 -0400 Received: from dsl081-033-126.lax1.dsl.speakeasy.net ([64.81.33.126]:52975 "EHLO bifrost.lang.hm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756116AbXHETL1 (ORCPT ); Sun, 5 Aug 2007 15:11:27 -0400 Date: Sun, 5 Aug 2007 12:03:21 -0700 (PDT) From: david@lang.hm X-X-Sender: dlang@asgard.lang.hm To: Diego Calleja cc: Ingo Molnar , Alan Cox , J??rn Engel , Jeff Garzik , Linus Torvalds , Peter Zijlstra , linux-mm@kvack.org, Linux Kernel Mailing List , miklos@szeredi.hu, akpm@linux-foundation.org, neilb@suse.de, dgc@sgi.com, tomoki.sekiyama.qu@hitachi.com, nikita@clusterfs.com, trond.myklebust@fys.uio.no, yingchao.zhou@gmail.com, richard@rsk.demon.co.uk Subject: Re: [PATCH 00/23] per device dirty throttling -v8 In-Reply-To: <20070805152231.aba9428a.diegocg@gmail.com> Message-ID: 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> <20070805152231.aba9428a.diegocg@gmail.com> MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="680960-1699270386-1186340601=:6905" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2246 Lines: 52 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --680960-1699270386-1186340601=:6905 Content-Type: TEXT/PLAIN; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8BIT On Sun, 5 Aug 2007, Diego Calleja wrote: > El Sun, 5 Aug 2007 09:13:20 +0200, Ingo Molnar escribi?: > >> 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 > > > And as everybody knows in servers is a popular practice to disable it. > According to an interview to the kernel.org admins.... > > "Beyond that, Peter noted, "very little fancy is going on, and that is good > because fancy is hard to maintain." He explained that the only fancy thing > being done is that all filesystems are mounted noatime meaning that the > system doesn't have to make writes to the filesystem for files which are > simply being read, "that cut the load average in half." > > I bet that some people would consider such performance hit a bug... > actually, it's popular practice to disable it by people who know how big a hit it is and know how few programs use it. i've been a linux sysadmin for 10 years, and have known about noatime for at least 7 years, but I always thought of it in the catagory of 'use it only on your performance critical machines where you are trying to extract every ounce of performance, and keep an eye out for things misbehaving' I never imagined that itwas the 20%+ hit that is being described, and with so little impact, or I would have switched to it across the board years ago. I'll bet there are a lot of admins out there in the same boat. adding an option in the kernel to change the default sounds like a very good first step, even if the default isn't changed today. David Lang --680960-1699270386-1186340601=:6905-- - 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/