From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755613Ab1CWRrY (ORCPT ); Wed, 23 Mar 2011 13:47:24 -0400 Received: from mga02.intel.com ([134.134.136.20]:11322 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753055Ab1CWRrW (ORCPT ); Wed, 23 Mar 2011 13:47:22 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.63,232,1299484800"; d="scan'208";a="616919052" From: Andi Kleen To: Linus Torvalds Cc: Ingo Molnar , Pekka Enberg , Jesper Juhl , linux-kernel@vger.kernel.org, Andrew Morton , "Paul E. McKenney" , Daniel Lezcano , Eric Paris , Roman Zippel , linux-kbuild@vger.kernel.org, Steven Rostedt Subject: Re: PATCH][RFC][resend] CC_OPTIMIZE_FOR_SIZE should default to N References: <20110322102741.GA4448@elte.hu> Date: Wed, 23 Mar 2011 10:45:48 -0700 In-Reply-To: (Linus Torvalds's message of "Tue, 22 Mar 2011 09:59:59 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus Torvalds writes: > On Tue, Mar 22, 2011 at 3:27 AM, Ingo Molnar wrote: >> >> If that situation has changed - if GCC has regressed in this area then a commit >> changing the default IMHO gains a lot of credibility if it is backed by careful >> measurements using perf stat --repeat or similar tools. > > Also, please don't back up any numbers for the "-O2 is faster than > -Os" case with some benchmark that is hot in the caches. Haven't done it recently, but some time last year -O2 vs -Os made a measurable difference in large OLTP benchmarks. (-Os being worse of course -- friends don't let friends use -Os) -Andi -- ak@linux.intel.com -- Speaking for myself only