From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755985Ab1K3N3j (ORCPT ); Wed, 30 Nov 2011 08:29:39 -0500 Received: from mga14.intel.com ([143.182.124.37]:47574 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755581Ab1K3N3h (ORCPT ); Wed, 30 Nov 2011 08:29:37 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.69,596,1315206000"; d="scan'208";a="80637996" Date: Wed, 30 Nov 2011 21:29:28 +0800 From: Wu Fengguang To: Christian Ehrhardt Cc: Dave Chinner , Jan Kara , Christoph Hellwig , Andrew Morton , Linux Memory Management List , "linux-fsdevel@vger.kernel.org" , Ankit Jain , Rik van Riel , Nikanth Karthikesan , LKML , Andi Kleen Subject: Re: [PATCH 2/8] readahead: make default readahead size a kernel parameter Message-ID: <20111130132928.GA31589@localhost> References: <20111121091819.394895091@intel.com> <20111121093846.251104145@intel.com> <20111121100137.GC5084@infradead.org> <20111121113540.GB8895@localhost> <20111124222822.GG29519@quack.suse.cz> <20111125003633.GP2386@dastard> <20111128023922.GA2141@localhost> <4ED629CB.401@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4ED629CB.401@linux.vnet.ibm.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 30, 2011 at 09:04:11PM +0800, Christian Ehrhardt wrote: > > > On 11/28/2011 03:39 AM, Wu Fengguang wrote: > > On Fri, Nov 25, 2011 at 08:36:33AM +0800, Dave Chinner wrote: > >> On Thu, Nov 24, 2011 at 11:28:22PM +0100, Jan Kara wrote: > >>> On Mon 21-11-11 19:35:40, Wu Fengguang wrote: > >>>> On Mon, Nov 21, 2011 at 06:01:37PM +0800, Christoph Hellwig wrote: > >>>>> On Mon, Nov 21, 2011 at 05:18:21PM +0800, Wu Fengguang wrote: > >>>>>> From: Nikanth Karthikesan > >>>>>> > [...] > > >> > >> And one that has already been in use for exactly this purpose for > >> years. Indeed, it's far more flexible because you can give different > >> types of devices different default readahead settings quite easily, > >> and it you can set different defaults for just about any tunable > >> parameter (e.g. readahead, ctq depth, max IO sizes, etc) in the same > >> way. > > > > I'm interested in this usage, too. Would you share some of your rules? > > > > FYI - This is an example of a rules Suse delivers in SLES @ s390 for a > while now. With little modifications it could be used for all Dave > mentioned above. It's a really good example, thank you! > cat /etc/udev/rules.d/60-readahead.rules > # > > > > # Rules to set an increased default max readahead size for s390 disk > devices > > > # This file should be installed in /etc/udev/rules.d > > > > # > > SUBSYSTEM!="block", GOTO="ra_end" > > ACTION!="add", GOTO="ra_end" > > # on device add set initial readahead to 512 (instead of in kernel 128) > > KERNEL=="sd*[!0-9]", ATTR{queue/read_ahead_kb}="512" > > KERNEL=="dasd*[!0-9]", ATTR{queue/read_ahead_kb}="512" So SLES (@s390 and maybe more) is already shipping with 512kb readahead size? Good to know this! Thanks, Fengguang > > > > LABEL="ra_end" > > -- > > Grüsse / regards, Christian Ehrhardt > IBM Linux Technology Center, System z Linux Performance