From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from LGEMRELSE7Q.lge.com ([156.147.1.151]:49965 "EHLO LGEMRELSE7Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755703Ab3BAIPH (ORCPT ); Fri, 1 Feb 2013 03:15:07 -0500 Message-ID: <510B7984.3060509@lge.com> Date: Fri, 01 Feb 2013 17:15:00 +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> <20130128142510.68092e10.akpm@linux-foundation.org> <20130129101549.GP23505@n2100.arm.linux.org.uk> <34874167.ghObrToI03@fb07-iapwap2> In-Reply-To: <34874167.ghObrToI03@fb07-iapwap2> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: Egon Alter Cc: linux-arm-kernel@lists.infradead.org, Russell King - ARM Linux , Andrew Morton , Michal Marek , hyojun.im@lge.com, raphael.andy.lee@gmail.com, linux-kbuild@vger.kernel.org, gunho.lee@lge.com, namhyung.kim@lge.com, x86@kernel.org, linux-kernel@vger.kernel.org, Josh Triplett , Nitin Gupta , Richard Purdie , Ingo Molnar , Joe Millenbach , chan.jeong@lge.com, "H. Peter Anvin" , Thomas Gleixner , Albin Tonnerre , CE Linux Developers List , minchan.kim@lge.com On 2013-01-29 오후 8:43, Egon Alter wrote: > Am Dienstag, 29. Januar 2013, 10:15:49 schrieb Russell King - ARM Linux: >> On Mon, Jan 28, 2013 at 02:25:10PM -0800, Andrew Morton wrote: >>> 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? >> Well... when I saw this my immediate reaction was "oh no, yet another >> decompressor for the kernel". We have five of these things already. >> Do we really need a sixth? >> >> My feeling is that we should have: >> - one decompressor which is the fastest >> - one decompressor for the highest compression ratio >> - one popular decompressor (eg conventional gzip) > the problem gets more complicated as the "fastest" decompressor usually > creates larger images which need more time to load from the storage, e.g. a > one MB larger image on a 10 MB/s storage (note: bootloaders often configure > the storage controllers in slow modes) gives 100 ms more boot time, thus > eating the gain of a "fast decompressor". Yes, the larger image could matter. Definitely it takes longer. Here are some updated test cases: Including "loading time" lzo lz4 loading time: 480ms 510ms decompression time: 336ms 180ms(with efficient unaligned memory access enabled and ARM optimization) total time: 816ms 690ms lz4 is still 15% faster in total time. This one is similar to the simulated result by Russell King. Thanks, Kyungsik