From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22431 invoked by alias); 28 Dec 2008 14:47:17 -0000 Received: (qmail 22420 invoked by uid 22791); 28 Dec 2008 14:47:17 -0000 X-SWARE-Spam-Status: No, hits=-2.1 required=5.0 tests=AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from smtp123.sbc.mail.sp1.yahoo.com (HELO smtp123.sbc.mail.sp1.yahoo.com) (69.147.64.96) by sourceware.org (qpsmtpd/0.43rc1) with SMTP; Sun, 28 Dec 2008 14:46:26 +0000 Received: (qmail 62803 invoked from network); 28 Dec 2008 14:46:25 -0000 Received: from unknown (HELO ?192.168.1.102?) (TimothyPrince@99.13.231.72 with plain) by smtp123.sbc.mail.sp1.yahoo.com with SMTP; 28 Dec 2008 14:46:24 -0000 Message-ID: <49579140.6030402@sbcglobal.net> Date: Sun, 28 Dec 2008 16:33:00 -0000 From: Tim Prince Reply-To: tprince@computer.org User-Agent: Thunderbird 2.0.0.18 (X11/20081112) MIME-Version: 1.0 To: tomgogh20@yahoo.com CC: tprince@computer.org, gcc-help@gcc.gnu.org Subject: Re: core2 flag for arch on gcc 4.3.2 References: <869404.1220.qm@web31405.mail.mud.yahoo.com> In-Reply-To: <869404.1220.qm@web31405.mail.mud.yahoo.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Mailing-List: contact gcc-help-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-help-owner@gcc.gnu.org X-SW-Source: 2008-12/txt/msg00263.txt.bz2 tom gogh wrote: > Hi Tim, > sorry for not making it clear. > I am building Gentoo 2008.0 and gcc supported is 4.1.2 which only > supports -mnocona for core 2 duo processor. > By migrating to gcc 4.3.2 I will get tunning for core 2 with flag > -mcore2 but, it involves going to unsupported gcc for Gentoo. > So, I want to know what is the difference between -mnocona flag of gcc > versus -mcore2 flag of gcc 4.3.2. Is it worth in terms of speed > optimization? > You're still being unclear. If you mean rebuilding an entire distro with an up to date compiler, there may be reasons why it hasn't been done already. If you don't have any idea what kernel or glibc operations you want to speed up, and how to measure it, and can't define what you mean by worth while, I have no qualification to make that determination for you. You give the impression that you haven't even compared the performance of the compilers on applications which matter to you, or haven't even thought about which applications matter. gcc has made great advances since 4.1, not only in optimizing for current CPU types, but in supporting OpenMP, auto-vectorization, and current language standards. Some of the more critical glibc operations are hand coded with inline asm, so as to prevent gcc optimization from helping out. If you choose not to use an up to date memcpy(), for example, you can make it perform much better by discarding the old glibc source and compiling C source with an up to date gcc. I don't know whether your gentoo uses up to date glibc, but I would doubt it, if the recommended gcc is so old.