Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754070AbZLCPuw (ORCPT ); Thu, 3 Dec 2009 10:50:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753284AbZLCPuv (ORCPT ); Thu, 3 Dec 2009 10:50:51 -0500 Received: from terminus.zytor.com ([198.137.202.10]:46744 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753328AbZLCPuv (ORCPT ); Thu, 3 Dec 2009 10:50:51 -0500 Message-ID: <4B17DD4A.2010305@zytor.com> Date: Thu, 03 Dec 2009 07:46:18 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.4pre) Gecko/20091014 Fedora/3.0-2.8.b4.fc11 Thunderbird/3.0b4 MIME-Version: 1.0 To: Ingo Molnar CC: "Ma, Ling" , Arjan van de Ven , Dave Jones , "tglx@linutronix.de" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH RFC] [X86] Compile Option Os versus O2 on latest x86 platform References: <1259222752-8161-1-git-send-email-ling.ma@intel.com> <20091126094930.GD32275@elte.hu> <8FED46E8A9CA574792FC7AACAC38FE7714FED213BE@PDSMSX501.ccr.corp.intel.com> <20091201021459.43d2142a@infradead.org> <8FED46E8A9CA574792FC7AACAC38FE7714FF5709D9@PDSMSX501.ccr.corp.intel.com> <4B17D3D3.1060502@zytor.com> <20091203153113.GB27324@elte.hu> In-Reply-To: <20091203153113.GB27324@elte.hu> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1291 Lines: 35 On 12/03/2009 07:31 AM, Ingo Molnar wrote: > > * H. Peter Anvin wrote: > >> On 12/03/2009 07:03 AM, Ma, Ling wrote: >>>> a key question is.. how much more memory do you have free due to -Os? >>>> (because memory is cache is performance on a system level as well) >>> The kernel code size from Os is 12M, that from O2 is 14M. >>>> and how much less icache pressure is there? >>> From perf stat report, cache reference(unified cache) from O2 is almost the same with Os. >> >> The icache pressure was substantially higher (by ~10%) in the reports >> that I saw. > > hm, icache numbers are not included in perf stat runs by default. Are > there some icache numbers i missed perhaps? > Sorry, you're right; cache references and cache misses. Furthermore, I'm wrong, I was looking at references *per unit time*, which just show that roughly the same number was squeezed into a shorter time. Never mind me... :-/ -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/