From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932554AbWFHHcR (ORCPT ); Thu, 8 Jun 2006 03:32:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932556AbWFHHcR (ORCPT ); Thu, 8 Jun 2006 03:32:17 -0400 Received: from pne-smtpout1-sn2.hy.skanova.net ([81.228.8.83]:25566 "EHLO pne-smtpout1-sn2.hy.skanova.net") by vger.kernel.org with ESMTP id S932554AbWFHHcQ (ORCPT ); Thu, 8 Jun 2006 03:32:16 -0400 Date: Thu, 8 Jun 2006 09:31:38 +0200 From: Voluspa To: Fengguang Wu Cc: akpm@osdl.org, arjan@infradead.org, Valdis.Kletnieks@vt.edu, diegocg@gmail.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] readahead: initial method - expected read size - fix fastcall Message-Id: <20060608093138.79f66acb.lista1@comhem.se> In-Reply-To: <349560742.21407@ustc.edu.cn> References: <349406446.10828@ustc.edu.cn> <20060604020738.31f43cb0.akpm@osdl.org> <1149413103.3109.90.camel@laptopd505.fenrus.org> <20060605031720.0017ae5e.lista1@comhem.se> <349560742.21407@ustc.edu.cn> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 6 Jun 2006 10:26:06 +0800 Fengguang Wu wrote: > On Mon, Jun 05, 2006 at 03:17:20AM +0200, Voluspa wrote: > > Patch: > > http://web.comhem.se/~u46139355/storetmp/adaptive-readahead-v14-linux-2.6.17-rc5-git-updated-june-04-2006.patch > > It seems that the patch has some problem: [...] > The above statements was displaced, rendering the if() clause to fail all the time. > That defeats the small file optimization, for ra_thrash_bytes will remain small. Which rendered all my testing invalid. Nice... It came about with the update-01to04of04 and must have elicited a "fuzz" that I neglected to check. Sorry to have caused you grief and extra work, Wu. I can only point towards the _Caveat and preemptive Mea Culpa_. > Voluspa, I attached an updated patch, including two more performance tunings. > Please take it when you find time to do more benchmarks, thanks. > > I'd suggest that you(and other kind people interested in testing it out) to run > blockdev --setra 2048 /dev/[sda/sda1/...] > before each benchmark to ensure fairness and simplicity of analysis, thanks. I'm in the process of writing up a new report after having tested for ca 6 hours straight (repenting mood). Will post in the original thread: Adaptive Readahead V14 - statistics question... http://marc.theaimsgroup.com/?t=114893205000004&r=1&w=2 The subject has a 'higher profile' than this one and might pull in future testers. Note to Andrew; Revised Conclusion: On _this_ machine, with _these_ operations, Adaptive Readahead in its current incarnation and default settings is a slight _loss_. However, if the readahead size is lowered from 2048 to 256, it becomes a slight _gain_ or at least stays in parity with normal readahead. Mvh Mats Johannesson --