Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756361AbZLCPbW (ORCPT ); Thu, 3 Dec 2009 10:31:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756119AbZLCPbW (ORCPT ); Thu, 3 Dec 2009 10:31:22 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:58219 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751053AbZLCPbV (ORCPT ); Thu, 3 Dec 2009 10:31:21 -0500 Date: Thu, 3 Dec 2009 16:31:13 +0100 From: Ingo Molnar To: "H. Peter Anvin" 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 Message-ID: <20091203153113.GB27324@elte.hu> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B17D3D3.1060502@zytor.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 894 Lines: 22 * 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? Ingo -- 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/