From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752639AbZHOGVg (ORCPT ); Sat, 15 Aug 2009 02:21:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751698AbZHOGVf (ORCPT ); Sat, 15 Aug 2009 02:21:35 -0400 Received: from smtp.nokia.com ([192.100.122.230]:43409 "EHLO mgw-mx03.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751348AbZHOGVe (ORCPT ); Sat, 15 Aug 2009 02:21:34 -0400 Message-ID: <4A8653DC.3050102@gmail.com> Date: Sat, 15 Aug 2009 09:21:16 +0300 From: Artem Bityutskiy User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1b3pre) Gecko/20090513 Fedora/3.0-2.3.beta2.fc11 Thunderbird/3.0b2 MIME-Version: 1.0 To: Zan Lynx CC: Linus Walleij , Robert Schwebel , 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 References: <20090814170228.GM13320@pengutronix.de> <4A85AAC4.7050505@acm.org> <20090814185731.GN13320@pengutronix.de> <63386a3d0908141401t6050f39ey8d85213aeccf748a@mail.gmail.com> <4A85D89F.8080900@acm.org> In-Reply-To: <4A85D89F.8080900@acm.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-OriginalArrivalTime: 15 Aug 2009 06:21:18.0686 (UTC) FILETIME=[99C52FE0:01CA1D70] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/15/2009 12:35 AM, Zan Lynx wrote: > Linus Walleij wrote: >> 2009/8/14 Robert Schwebel : >>> On Fri, Aug 14, 2009 at 12:19:48PM -0600, Zan Lynx 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. > > I thought of another thing to check related to slow decompression. If > the kernel, bootloader or hardware is in charge of setting CPU power and > speed scaling, then you should check that it boots with the CPU set at > maximum speed instead of slowest. zlib is slow on decompression, and lzo is much faster. So if you implement lzo compression, you'll probably speed things up a little as well. I saw some discussions about this on lkml. Having no compression at all may also be a good thing to try. -- Best Regards, Artem Bityutskiy (Артём Битюцкий)