From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754401AbYL0Klw (ORCPT ); Sat, 27 Dec 2008 05:41:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752807AbYL0Klo (ORCPT ); Sat, 27 Dec 2008 05:41:44 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:58517 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752799AbYL0Kln (ORCPT ); Sat, 27 Dec 2008 05:41:43 -0500 Date: Sat, 27 Dec 2008 11:41:23 +0100 From: Ingo Molnar To: Brian Gerst , Christoph Lameter , Thomas Gleixner , "H. Peter Anvin" , Jeremy Fitzhardinge , Alexander van Heukelum Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] x86-64: Convert the PDA to percpu. Message-ID: <20081227104123.GH14639@elte.hu> References: <1230052506-5041-1-git-send-email-brgerst@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1230052506-5041-1-git-send-email-brgerst@gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (Cc:-ed a few more people who might be interested in this) * Brian Gerst wrote: > This patch makes the PDA a normal per-cpu variable, allowing the > removal of the special allocator code. %gs still points to the > base of the PDA. > > Tested on a dual-core AMD64 system. > > Signed-off-by: Brian Gerst > --- > arch/x86/include/asm/pda.h | 3 -- > arch/x86/include/asm/percpu.h | 3 -- > arch/x86/include/asm/setup.h | 1 - > arch/x86/kernel/cpu/common.c | 6 ++-- > arch/x86/kernel/dumpstack_64.c | 8 ++-- > arch/x86/kernel/head64.c | 23 +------------ > arch/x86/kernel/irq.c | 2 +- > arch/x86/kernel/nmi.c | 2 +- > arch/x86/kernel/setup_percpu.c | 70 ++++++++-------------------------------- > arch/x86/kernel/smpboot.c | 58 +-------------------------------- > arch/x86/xen/enlighten.c | 2 +- > arch/x86/xen/smp.c | 12 +------ > 12 files changed, 27 insertions(+), 163 deletions(-) the simplification factor is significant. I'm wondering, have you measured the code size impact of this on say the defconfig x86 kernel? That will generally tell us how much worse optimizations the compiler does under this scheme. Ingo