From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935974AbXGMHIX (ORCPT ); Fri, 13 Jul 2007 03:08:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752498AbXGMHIQ (ORCPT ); Fri, 13 Jul 2007 03:08:16 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:32858 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752074AbXGMHIP (ORCPT ); Fri, 13 Jul 2007 03:08:15 -0400 Date: Fri, 13 Jul 2007 00:08:14 -0700 (PDT) Message-Id: <20070713.000814.102125147.davem@davemloft.net> To: clameter@sgi.com Cc: ak@suse.de, linux-kernel@vger.kernel.org, travis@sgi.com, jeremy@goop.org Subject: Re: x86: Convert cpu_core_map to be a per cpu variable From: David Miller In-Reply-To: References: X-Mailer: Mew version 5.1.52 on Emacs 21.4 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Christoph Lameter Date: Thu, 12 Jul 2007 23:58:06 -0700 (PDT) > cpu_core_map is currently an array defined using NR_CPUS. This means that > we overallocate since we will rarely really use the maximum > number of configured cpus. This may become a problem when we need to > increase the NR_CPUs on x86_64 for our new product line. I'm using NR_CPUS set to 1024 on my sparc64 workstation, it's not that bad to be honest :-) What kind of cpu arity are you talking about? > If we put the cpu_core_map into the per cpu area then it will be allocated > for each processor as it comes online. > > However, this means that the core map cannot be accessed until the per cpu > area has been allocated. Xen does a weird thing here looping over all > processors and zeroing the masks that are not yet allocated and that will > be zeroed when they are allocated. I commented the code out. Maybe there > is another purpose? Jeremy? > > Signed-off-by: Christoph Lameter Please take care of sparc64 if you're going to do this change. It uses cpu_core_map too.