From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755822AbYABU7F (ORCPT ); Wed, 2 Jan 2008 15:59:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758326AbYABU6r (ORCPT ); Wed, 2 Jan 2008 15:58:47 -0500 Received: from relay2.sgi.com ([192.48.171.30]:53095 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757749AbYABU6q (ORCPT ); Wed, 2 Jan 2008 15:58:46 -0500 Date: Wed, 2 Jan 2008 12:58:45 -0800 (PST) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Andi Kleen cc: Mike Travis , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Rusty Russell , tglx@linutronix.de, mingo@redhat.com Subject: Re: [PATCH 05/10] x86_64: Use generic percpu In-Reply-To: <200712290255.40233.ak@suse.de> Message-ID: References: <20071228001046.854702000@sgi.com> <200712281354.52453.ak@suse.de> <47757311.5050503@sgi.com> <200712290255.40233.ak@suse.de> 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 On Sat, 29 Dec 2007, Andi Kleen wrote: > Anyways the difference between the x86 percpu.h and the generic one is > that x86-64 uses a short cut through the PDA to get the current cpu > offset for the current CPU case. The generic one goes through > smp_processor_id()->array reference instead. No the patch also uses the pda. > I would request that this optimization is not being removed > without suitable replacement in the same patchkit. The optimization was not removed __my_cpu_offset is used to calculate the current offset which is using the pda. #define __my_cpu_offset read_pda(data_offset)