From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753583Ab3BAHBD (ORCPT ); Fri, 1 Feb 2013 02:01:03 -0500 Received: from LGEMRELSE6Q.lge.com ([156.147.1.121]:60613 "EHLO LGEMRELSE6Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750918Ab3BAHBA (ORCPT ); Fri, 1 Feb 2013 02:01:00 -0500 X-AuditID: 9c930179-b7c24ae00000119c-d7-510b6829b1fb Message-ID: <510B6829.7050908@lge.com> Date: Fri, 01 Feb 2013 16:00:57 +0900 From: "kyungsik.lee" User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20130107 Thunderbird/17.0.2 MIME-Version: 1.0 To: Rajesh Pawar CC: Andrew Morton , "H. Peter Anvin" , Michal Marek , Ingo Molnar , Thomas Gleixner , Russell King , linux-kernel@vger.kernel.org, linux-kbuild@jasper.es, linux-arm-kernel@lists.infradead.org, David Sterba , =?UTF-8?B?7J6E7Zqo7KSA?= , =?UTF-8?B?7KCV7LCs6reg?= , minchan@kernel.org, =?UTF-8?B?6rmA64Ko7ZiV?= , Richard Cochran , Egon Alter , CE Linux Developers List , markus@oberhumer.com, raphael.andy.lee@gmail.com Subject: Re: [RFC PATCH 0/4] Add support for LZ4-compressed kernels References: <1359179447-31118-1-git-send-email-kyungsik.lee@lge.com>, <20130128142510.68092e10.akpm@linux-foundation.org> <254788880.18003.1359493798737.JavaMail.tomcat@be12> In-Reply-To: <254788880.18003.1359493798737.JavaMail.tomcat@be12> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2013-01-30 오전 6:09, Rajesh Pawar wrote: >> 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? >> 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? > BTW, what happened to the proposed LZO update - woudn't it better to merge this first? > > Also, under the hood LZ4 seems to be quite similar to LZO, so probably > LZO speed would also greatly benefit from unaligned access and some other > ARM optimisations > I didn't test with the proposed LZO update you mentioned. Sorry, which one do you mean? I did some tests with the latest LZO in the mainline. As a result, LZO is not faster in an unaligned access enabled on ARM. Actually Slower. Decompression time: 336ms(383ms, with unaligned access enabled) You may refer to https://lkml.org/lkml/2012/10/7/85 to know more about it. Thanks, Kyungsik Thanks, Kyungsik