From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755482AbZHNVPr (ORCPT ); Fri, 14 Aug 2009 17:15:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755399AbZHNVPq (ORCPT ); Fri, 14 Aug 2009 17:15:46 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:43228 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755383AbZHNVPq (ORCPT ); Fri, 14 Aug 2009 17:15:46 -0400 Date: Fri, 14 Aug 2009 23:15:00 +0200 From: Robert Schwebel To: Linus Walleij Cc: Robert Schwebel , Zan Lynx , linux-kernel@vger.kernel.org, linux-embedded@vger.kernel.org, Arjan van de Ven , Tim Bird , kernel@pengutronix.de Subject: Re: New fast(?)-boot results on ARM Message-ID: <20090814211500.GC31727@pengutronix.de> References: <20090814170228.GM13320@pengutronix.de> <4A85AAC4.7050505@acm.org> <20090814185731.GN13320@pengutronix.de> <63386a3d0908141401t6050f39ey8d85213aeccf748a@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <63386a3d0908141401t6050f39ey8d85213aeccf748a@mail.gmail.com> X-Sent-From: Pengutronix Entwicklungszentrum Nord - Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Impressum: Pengutronix - Linux Solutions for Science and Industry Handelsregister: Amtsgericht Hildesheim, HRA 2686 Peiner Strasse 6-8, 31137 Hildesheim, Germany Phone: +49-5121-206917-0 | Fax: +49-5121-206917-5555 Inhaber: Dipl.-Ing. Robert Schwebel X-Message-Flag: See Message Headers for Impressum X-Uptime: 23:13:33 up 9 days, 8:32, 3 users, load average: 0.08, 0.04, 0.00 User-Agent: Mutt/1.5.18 (2008-05-17) X-SA-Exim-Connect-IP: 2001:6f8:1178:2:215:17ff:fe12:23b0 X-SA-Exim-Mail-From: rsc@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 14, 2009 at 11:01:58PM +0200, Linus Walleij wrote: > >> > That's factor 70 away from the 110 ms boot time Tim has talked about > >> > some days ago (and he measured on an ARM cpu which had almost half > >> > the speed of this one), and I'm wondering what we can do to improve > >> > the boot time. > >> > >> 2.4s in uncompression? That seems like an obvious target for > >> improvement. > > > > Indeed, we'll check that. > > We got rid of uncompression on a flash-based system vastly improving > boot time. The reason is that compressed kernels are faster only when > the throughput to the persistent storage is lower than the decompression > throughput, and on typical embedded systems with DMA the throughput to > memory outperforms the CPU-based decompression. > > Of course it depends on a lot of stuff like performance of flash controller, > kernel storage filesystem performance, DMA controller performance, > cache architecture etc so it's individual per-system. We have also done that on NOR based systems, but I'm not sure if it will work out for NAND as well. Thanks, rsc -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |