From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751147AbWH3Qsm (ORCPT ); Wed, 30 Aug 2006 12:48:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751154AbWH3Qsl (ORCPT ); Wed, 30 Aug 2006 12:48:41 -0400 Received: from ns1.suse.de ([195.135.220.2]:15495 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S1751147AbWH3Qsl (ORCPT ); Wed, 30 Aug 2006 12:48:41 -0400 From: Andi Kleen To: Jeremy Fitzhardinge Subject: Re: [PATCH RFC 0/6] Implement per-processor data areas for i386. Date: Wed, 30 Aug 2006 18:48:39 +0200 User-Agent: KMail/1.9.3 Cc: Chuck Ebbert <76306.1226@compuserve.com>, linux-kernel , Zachary Amsden , Jan Beulich , Andrew Morton References: <200608300838_MC3-1-C9C6-CA79@compuserve.com> <44F5BF29.7080004@goop.org> In-Reply-To: <44F5BF29.7080004@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200608301848.39443.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > > I don't think so. The whole point is to make the pda easily accessible > with simple addressing modes based on %gs:. I have been wondering if > we can modify the percpu mechanism to get the linker to construct the > layout of the pda, so that all the existing percpu stuff can be > transparently moved into the pda and accessed efficiently. I think it > would be pretty tricky to get it all working though... I tried that once on x86-64, but it wasn't possible because the linker is missing the right relocations. It has something on the first look similar for __thread data in user space, but it wasn't usable for the kernel. Even with a single indirection it is still far more efficient than a array lookup. -Andi