From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759092AbXGVCjg (ORCPT ); Sat, 21 Jul 2007 22:39:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753393AbXGVCj3 (ORCPT ); Sat, 21 Jul 2007 22:39:29 -0400 Received: from smtp.ustc.edu.cn ([202.38.64.16]:50125 "HELO ustc.edu.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1750909AbXGVCj2 (ORCPT ); Sat, 21 Jul 2007 22:39:28 -0400 Message-ID: <385071955.09308@ustc.edu.cn> X-EYOUMAIL-SMTPAUTH: wfg@mail.ustc.edu.cn Date: Sun, 22 Jul 2007 10:39:23 +0800 From: Fengguang Wu To: Peter Zijlstra Cc: linux-kernel , riel , Andrew Morton , Rusty Russell , Tim Pepper , Chris Snook , Dave Jones Subject: Re: [PATCH 0/3] readahead drop behind and size adjustment Message-ID: <20070722023923.GA6438@mail.ustc.edu.cn> Mail-Followup-To: Peter Zijlstra , linux-kernel , riel , Andrew Morton , Rusty Russell , Tim Pepper , Chris Snook , Dave Jones References: <20070721210005.000228000@chello.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070721210005.000228000@chello.nl> X-GPG-Fingerprint: 53D2 DDCE AB5C 8DC6 188B 1CB1 F766 DA34 8D8B 1C6D User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 21, 2007 at 11:00:05PM +0200, Peter Zijlstra wrote: > The various readahead bits I have lying about. > > Wu, would you agree with asking Andrew to stick these behind your latest > readahead series? They are generally good feature to have. Thank you! - default readahead size It makes sense to raise it beyond 128K. 1M default readahead absolutely makes sense for sequential workloads. For the desktop, this increases boot speed and readahead misses, both due to more aggressive mmap read-around. Most users will be glad to feel the speedup, and happily ignore the readahead misses, which may be "invisible" in case of large memory. In theory, the distributions can do the same tuning. So we have an interesting question for Dave: Does fedora desktop raise the default readahead size? Why or why not? It goes so far to do userland readahead ;) - drop behind Sorry, I still doubt it will benefit all/most workloads. Leave it off by default, and leave the enabling decision to Dave? I do hope that it help general desktops.