Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932282AbWEDMfN (ORCPT ); Thu, 4 May 2006 08:35:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932287AbWEDMfN (ORCPT ); Thu, 4 May 2006 08:35:13 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:5548 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S932282AbWEDMfL (ORCPT ); Thu, 4 May 2006 08:35:11 -0400 Subject: Re: [RFC] kernel facilities for cache prefetching From: Arjan van de Ven To: Wu Fengguang Cc: "Ph. Marek" , Linus Torvalds , Linda Walsh , linux-kernel@vger.kernel.org, Andrew Morton , Jens Axboe , Nick Piggin , Badari Pulavarty In-Reply-To: <20060504121454.GB6008@mail.ustc.edu.cn> References: <346556235.24875@ustc.edu.cn> <44594AA9.8020906@tlinx.org> <200605040908.10727.philipp.marek@bmlv.gv.at> <1146728004.3101.17.camel@laptopd505.fenrus.org> <20060504121454.GB6008@mail.ustc.edu.cn> Content-Type: text/plain Date: Thu, 04 May 2006 14:34:55 +0200 Message-Id: <1146746095.3101.35.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1303 Lines: 30 On Thu, 2006-05-04 at 20:14 +0800, Wu Fengguang wrote: > On Thu, May 04, 2006 at 09:33:24AM +0200, Arjan van de Ven wrote: > > > > > > > Ascending block numbers on disk can be read very fast, as the disk needs no or > > > less seeking. That's even true for stripes and mirrors. (I grant you that > > > there are complicated setups out there, but these could be handled similar.) > > > > > > > > > btw this all really spells out that you may want to do this as a device > > mapper thing; eg have a device mapper module that can do "lookaside" to > > a different order/mirror block whatever. The filesystem just doesn't > > want to know; do it at the DM level ;) That also solves the entire > > caching layering problem etc ;) > > I guess some big corps might want to install such a layer into their > storage products ;) maybe, could be. Doing it at this level also has the advantage that fs metadata becomes seek free as well; since that is mostly fixed-location inside the fs, reordering that on an fs-level is really hard.. on a dm level.. easy. - 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/