From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from LGEMRELSE1Q.lge.com ([156.147.1.111]:62830 "EHLO LGEMRELSE1Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751098Ab3BAHNo (ORCPT ); Fri, 1 Feb 2013 02:13:44 -0500 Message-ID: <510B6B24.8040000@lge.com> Date: Fri, 01 Feb 2013 16:13:40 +0900 From: "kyungsik.lee" MIME-Version: 1.0 Subject: Re: [RFC PATCH 0/4] Add support for LZ4-compressed kernels References: <1359179447-31118-1-git-send-email-kyungsik.lee@lge.com> <20130129225508.GC30535@twin.jikos.cz> In-Reply-To: <20130129225508.GC30535@twin.jikos.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: dsterba@suse.cz Cc: 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 , Andrew Morton , 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 On 2013-01-30 오전 7:55, David Sterba wrote: > On Sat, Jan 26, 2013 at 02:50:43PM +0900, Kyungsik Lee wrote: >> This patchset is for supporting LZ4 compressed kernel and initial ramdisk on >> the x86 and ARM architectures. > Have you considered the 'high compression' mode of lz4? > http://code.google.com/p/lz4/source/browse/trunk/lz4hc.c > > The compression format remains the same, the compressor tries harder > (but is slower), resulting compression ratio is better. > > an examle compression for vmlinux.bin of x86_64 build: > > input size: 16509520 bytes > > lz4 (svn 88): > output size: 6393684 (38.7%) > compression time: 41.7 ms (395 MB/s) > decompression time: 13.7 ms (1204 MB/s) > > lz4hc (svn 88): > output size: 5319137 (32.2%) > compression time: 683 ms (24 MB/s) > decompression time: 13.1 ms (1259 MB/s) > > compressed file delta: 6393684 - 5319137 = 1074547 ~ 1MB > > tested on a Nehalem box; same test on my slow desktop gives > > lz4: > compression time: 97 ms (169 MB/s) > decompression time: 25.7 ms (643 MB/s) > > lz4hc: > compression time: 1386 ms (11 MB/s) > decompression time: 26 ms (619 MB/s) > > While the decompression time is almost the same, image size is smaller. > The kernel image compression is run in userspace and the low speed is > not much of concern for a one-time operation. > > For the reference, lzo (current kernel version) run on the destktop: > > output size: 6026256 (36.5%) > decompression time: 79.6 ms (207 MB/s) > >> It seems that it’s worth trying LZ4 compressed kernel image or ramdisk >> for making the kernel boot more faster. > There's another potential user of lz4: btrfs. I've submitted a feature > preview integrating lz4 compression > http://thread.gmane.org/gmane.comp.file-systems.btrfs/15744 > and we have tried to integrate the HC mode as well > http://thread.gmane.org/gmane.comp.file-systems.btrfs/18165 > . > So far it's on a slow track, conceptually it works, but I the code needs > some work so it could live under lib/* (we've used the svn sources > with minor changes, no kernel coding style). It would be easier for me > to enhance the existing lib/lz4/* codebase. > > Also zram could consider lz4, I'm not sure if there are other potential > users. Yes, I guess squash fs and crypto would also benefit from lz4. Thanks, Kyungsik