Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759421AbXHER76 (ORCPT ); Sun, 5 Aug 2007 13:59:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753366AbXHER7u (ORCPT ); Sun, 5 Aug 2007 13:59:50 -0400 Received: from srv5.dvmed.net ([207.36.208.214]:43924 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753298AbXHER7t (ORCPT ); Sun, 5 Aug 2007 13:59:49 -0400 Message-ID: <46B60FFC.2000909@garzik.org> Date: Sun, 05 Aug 2007 13:59:24 -0400 From: Jeff Garzik User-Agent: Thunderbird 1.5.0.12 (X11/20070719) MIME-Version: 1.0 To: Ingo Molnar CC: Theodore Tso , Alan Cox , Claudio Martins , =?ISO-8859-1?Q?J=F6rn_Engel?= , 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, david@lang.hm Subject: Re: [PATCH 00/23] per device dirty throttling -v8 References: <20070803123712.987126000@chello.nl> <46B4E161.9080100@garzik.org> <20070804224706.617500a0@the-village.bc.nu> <200708050051.40758.ctpm@ist.utl.pt> <20070805014926.400d0608@the-village.bc.nu> <20070805144645.GA28263@thunk.org> <20070805175547.GC3244@elte.hu> In-Reply-To: <20070805175547.GC3244@elte.hu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.3 (----) X-Spam-Report: SpamAssassin version 3.1.9 on srv5.dvmed.net summary: Content analysis details: (-4.3 points, 5.0 required) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1357 Lines: 32 Ingo Molnar wrote: > * Theodore Tso wrote: > >> If you are always reading from the same small set of files (i.e., a >> database workload), then those inodes only get updated every 5 seconds >> (the traditional/default metadata update sync time, as well as the >> default ext3 journal update time), it's no big deal. Or if you are >> running a mail server, most of the time the mail queue files are >> getting updated anyway as you process them, and usually the mail is >> delivered before 5 seconds is up anyway. >> >> So earlier, when Ingo characterized it as, "whenever you read from a >> file, even one in memory cache.... do a write!", it's probably a bit >> unfair. Traditional Unix systems simply had very different workload >> characteristics than many modern dekstop systems today. > > yeah, i didnt mean to say that it is _always_ a big issue, but "only a > small number of files are read" is a very, very small minority of even > the database server world. OTOH, consider a popular Linux task, web serving. atime results in a lot of unnecessary disk traffic. Jeff - 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/