Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753827AbbDHMTG (ORCPT ); Wed, 8 Apr 2015 08:19:06 -0400 Received: from mail-vn0-f42.google.com ([209.85.216.42]:43005 "EHLO mail-vn0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751572AbbDHMTD (ORCPT ); Wed, 8 Apr 2015 08:19:03 -0400 MIME-Version: 1.0 In-Reply-To: References: <1428388995.3152.10.camel@gmail.com> <1428401356.3152.38.camel@gmail.com> <55241C51.8040107@gmail.com> Date: Wed, 8 Apr 2015 14:19:02 +0200 Message-ID: Subject: Re: Why not build kernel with -O3 From: Richard Weinberger To: Pengfei Yuan <0xcoolypf@gmail.com> Cc: Austin S Hemmelgarn , Mike Galbraith , LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 725 Lines: 21 On Wed, Apr 8, 2015 at 3:00 AM, Pengfei Yuan <0xcoolypf@gmail.com> wrote: > Could you please provide some examples that I can investigate? > Thanks! It would be awesome if you could find out which gcc optimizations cause the speed up. "gcc -c -Q -O3 --help=optimizers" will help you. Please also double check your results. You need do to multiple runs, etc... Especially the redis speed up looks odd. Does redis really spend that much time in the kernel? -- Thanks, //richard -- 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/