From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756601Ab3A2E3U (ORCPT ); Mon, 28 Jan 2013 23:29:20 -0500 Received: from relais.videotron.ca ([24.201.245.36]:14744 "EHLO relais.videotron.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753872Ab3A2E3S (ORCPT ); Mon, 28 Jan 2013 23:29:18 -0500 MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: TEXT/PLAIN; CHARSET=US-ASCII Date: Mon, 28 Jan 2013 23:29:14 -0500 (EST) From: Nicolas Pitre To: Andrew Morton Cc: Kyungsik Lee , Russell King , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Michal Marek , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, x86@kernel.org, Nitin Gupta , Richard Purdie , Josh Triplett , Joe Millenbach , Albin Tonnerre , hyojun.im@lge.com, chan.jeong@lge.com, gunho.lee@lge.com, minchan.kim@lge.com, namhyung.kim@lge.com, raphael.andy.lee@gmail.com, CE Linux Developers List Subject: Re: [RFC PATCH 0/4] Add support for LZ4-compressed kernels In-reply-to: <20130128142510.68092e10.akpm@linux-foundation.org> Message-id: References: <1359179447-31118-1-git-send-email-kyungsik.lee@lge.com> <20130128142510.68092e10.akpm@linux-foundation.org> User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 28 Jan 2013, Andrew Morton wrote: > On Sat, 26 Jan 2013 14:50:43 +0900 > Kyungsik Lee wrote: > > > This patchset is for supporting LZ4 compressed kernel and initial ramdisk on > > the x86 and ARM architectures. > > > > According to http://code.google.com/p/lz4/, LZ4 is a very fast lossless > > compression algorithm and also features an extremely fast decoder. > > > > Kernel Decompression APIs are based on implementation by Yann Collet > > (http://code.google.com/p/lz4/source/checkout). > > De/compression Tools are also provided from the site above. > > > > The initial test result on ARM(v7) based board shows that the size of kernel > > with LZ4 compressed is 8% bigger than LZO compressed but the decompressing > > speed is faster(especially under the enabled unaligned memory access). > > > > Test: 3.4 based kernel built with many modules > > Uncompressed kernel size: 13MB > > lzo: 6.3MB, 301ms > > lz4: 6.8MB, 251ms(167ms, with enabled unaligned memory access) > > > > It seems that it___s worth trying LZ4 compressed kernel image or ramdisk > > for making the kernel boot more faster. > > > > ... > > > > 20 files changed, 663 insertions(+), 3 deletions(-) > > > > ... > > > > What's this "with enabled unaligned memory access" thing? You mean "if > the arch supports CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS"? If so, > that's only x86, which isn't really in the target market for this > patch, yes? I'm guessing this is referring to commit 5010192d5a. > It's a lot of code for a 50ms boot-time improvement. Does anyone have > any opinions on whether or not the benefits are worth the cost? Well, we used to have only one compressed format. Now we have nearly half a dozen, with the same worthiness issue between themselves. Either we keep it very simple, or we make it very flexible. The former would argue in favor of removing some of the existing formats, the later would let this new format in. Nicolas