From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761469AbXGMQeW (ORCPT ); Fri, 13 Jul 2007 12:34:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760617AbXGMQeG (ORCPT ); Fri, 13 Jul 2007 12:34:06 -0400 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:39521 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1760214AbXGMQeE (ORCPT ); Fri, 13 Jul 2007 12:34:04 -0400 Date: Fri, 13 Jul 2007 09:34:02 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: David Miller 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 In-Reply-To: <20070713.000814.102125147.davem@davemloft.net> Message-ID: References: <20070713.000814.102125147.davem@davemloft.net> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 13 Jul 2007, David Miller wrote: > 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? Up to 16k. > > 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. But the code modified here is x86_64 and i386 specific? Is there an overlap?