From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265203AbTLROhy (ORCPT ); Thu, 18 Dec 2003 09:37:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265204AbTLROhy (ORCPT ); Thu, 18 Dec 2003 09:37:54 -0500 Received: from web13908.mail.yahoo.com ([216.136.175.71]:36357 "HELO web13908.mail.yahoo.com") by vger.kernel.org with SMTP id S265203AbTLROhn (ORCPT ); Thu, 18 Dec 2003 09:37:43 -0500 Message-ID: <20031218143741.25747.qmail@web13908.mail.yahoo.com> X-RocketYMMF: knobi.rm Date: Thu, 18 Dec 2003 06:37:41 -0800 (PST) From: Martin Knoblauch Reply-To: knobi@knobisoft.de Subject: Re: RAID-0 read perf. decrease after 2.4.20 To: Marcelo Tosatti Cc: linux-kernel@vger.kernel.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --- Marcelo Tosatti wrote: > > > On Tue, 16 Dec 2003, Martin Knoblauch wrote: > > > On Monday 08 December 2003 13:47, Marcelo Tosatti wrote: > > > > Hi Marcelo, > > > > > 2.4.20-aa included rmap and some VM modifications most notably > > > "drop_behind()" logic which I believe should be the reason for > the > > huge > > > read speedups. Can you please try it? Against 2.4.23. > > > > Just some feedback: > > > > echo 511 > /proc/sys/vm/max-readahead > > > > brings back the read performance of my 30 disks on 4 controller > > LVM/RAID0. > > Great. > Indeed :-) Just to clarify - the modification of max-readahead was sufficient to "fix" the observed read performance degradation. I did not apply (or reverse) anything on top of 2.4.22. Actually 255 would have been sufficient, 511 proved to be a small bit better :-)) Martin ===== ------------------------------------------------------ Martin Knoblauch email: k n o b i AT knobisoft DOT de www: http://www.knobisoft.de