From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752422Ab3AZPkL (ORCPT ); Sat, 26 Jan 2013 10:40:11 -0500 Received: from mail.skyhub.de ([78.46.96.112]:47758 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751050Ab3AZPkJ (ORCPT ); Sat, 26 Jan 2013 10:40:09 -0500 Date: Sat, 26 Jan 2013 16:42:56 +0100 From: Borislav Petkov To: "H. Peter Anvin" Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, arjan@linux.intel.com, jbeulich@suse.com, ling.ml@alipay.com, rostedt@goodmis.org, akpm@linux-foundation.org, tglx@linutronix.de, linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/asm] x86/defconfig: Turn on CONFIG_CC_OPTIMIZE_FOR_SIZE= y in the 64-bit defconfig Message-ID: <20130126154256.GB16044@pd.tnic> Mail-Followup-To: Borislav Petkov , "H. Peter Anvin" , mingo@kernel.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, arjan@linux.intel.com, jbeulich@suse.com, ling.ml@alipay.com, rostedt@goodmis.org, akpm@linux-foundation.org, tglx@linutronix.de, linux-tip-commits@vger.kernel.org References: <1359123061-6139-1-git-send-email-ling.ma@alipay.com> <20130126125208.GC21395@pd.tnic> <8b0dfc4a-6f9c-498a-9844-4d99deb3052f@email.android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8b0dfc4a-6f9c-498a-9844-4d99deb3052f@email.android.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 26, 2013 at 07:18:26AM -0800, H. Peter Anvin wrote: > On the CPUs Ling is testing on the downsides of -Os probably matter >less, in particular since rep movsb works well. > > It is questionable as a generic default, though. > > The whole -Ok discussion came from that. Hmm, maybe this warrants some sort of a text addition to the config option about when and where it is ok to select -Os. Also, is it so that on those CPUs, -Os is always better or at least neutral so that it doesn't cause any perf regressions when people enable it? I mean, I see only netperf and volano runs in the commit message, maybe running a comprehensive set of benchmarks would give us a much more detailed picture... Thanks. -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. --