From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6342FC433E1 for ; Fri, 24 Jul 2020 01:06:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 413FA206E3 for ; Fri, 24 Jul 2020 01:06:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726349AbgGXBGu (ORCPT ); Thu, 23 Jul 2020 21:06:50 -0400 Received: from mga18.intel.com ([134.134.136.126]:24762 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726010AbgGXBGu (ORCPT ); Thu, 23 Jul 2020 21:06:50 -0400 IronPort-SDR: bJFi10tTnHFOCu0w0BlbIAH/eoqdBah8UZ5vcMAKLirlrFXkungTFPEb6B7RvWdCn8aEHq3qyo MATYeWky1rGA== X-IronPort-AV: E=McAfee;i="6000,8403,9691"; a="138142282" X-IronPort-AV: E=Sophos;i="5.75,388,1589266800"; d="scan'208";a="138142282" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jul 2020 18:06:49 -0700 IronPort-SDR: bMs8aUGR39PW22vlKUmh73TYXuFQXfvozPE0Xtpp30nbttMg+9c6y9UWHmmYq/C3LjimvK86Rk OBBDfyzqeH0w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,388,1589266800"; d="scan'208";a="463054103" Received: from shbuild999.sh.intel.com (HELO localhost) ([10.239.146.107]) by orsmga005.jf.intel.com with ESMTP; 23 Jul 2020 18:06:46 -0700 Date: Fri, 24 Jul 2020 09:06:45 +0800 From: Feng Tang To: Andrew Morton Cc: Masahiro Yamada , Michal Marek , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , andi.kleen@intel.com, ying.huang@intel.com, andriy.shevchenko@intel.com, philip.li@intel.com, rong.a.chen@intel.com Subject: Re: [RFC PATCH] makefile: add debug option to enable function aligned on 32 bytes Message-ID: <20200724010645.GB65362@shbuild999.sh.intel.com> References: <1595475001-90945-1-git-send-email-feng.tang@intel.com> <20200722203919.8b7c9b35ff51d66550c3846c@linux-foundation.org> <20200723062933.GA65362@shbuild999.sh.intel.com> <20200723175704.44c4b890e76dc6dc68bf3674@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200723175704.44c4b890e76dc6dc68bf3674@linux-foundation.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 23, 2020 at 05:57:04PM -0700, Andrew Morton wrote: > On Thu, 23 Jul 2020 14:29:33 +0800 Feng Tang wrote: > > > > > gcc has an option '-falign-functions=n' to force text aligned, and with > > > > that option enabled, some of those performance changes will be gone, > > > > like [1][2][3]. > > > > > > > > Add this option so that developers and 0day can easily find performance > > > > bump caused by text alignment change, > > > > > > Would they use it this way, or would they simply always enable the > > > option to reduce the variability? > > > > I may mis-understood it in my last reply. If you are asking about how > > will developers and 0day use this option, for 0day, I've talked with > > 0day folks, they may just enable it by default, as 0day cares more about > > the performance delta caused by a commit (Adding Philip and Rong from > > 0day). > > OK, thanks, I suspected as much. > > The patch is so simple and probably-will-work, I guess we toss it in > there and see. Thanks! > However it would be good if the 0day people could use it for a while > and then provide some feedback on whether it is actually proving > useful. If not, we get to remove some stuff. Yes, 0day is a good user to try this. Thanks, Feng