Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422795AbWKPNIh (ORCPT ); Thu, 16 Nov 2006 08:08:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1423922AbWKPNIh (ORCPT ); Thu, 16 Nov 2006 08:08:37 -0500 Received: from moutng.kundenserver.de ([212.227.126.187]:18368 "EHLO moutng.kundenserver.de") by vger.kernel.org with ESMTP id S1422795AbWKPNIg convert rfc822-to-8bit (ORCPT ); Thu, 16 Nov 2006 08:08:36 -0500 From: Arnd Bergmann To: Christoph Lameter Subject: Re: [patch 2/2] enables booting a NUMA system where some nodes have no memory Date: Thu, 16 Nov 2006 14:08:25 +0100 User-Agent: KMail/1.9.5 Cc: Martin Bligh , Christian Krafft , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20061115193049.3457b44c@localhost> <200611160126.02016.arnd@arndb.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200611161408.26328.arnd@arndb.de> X-Provags-ID: kundenserver.de abuse@kundenserver.de login:c48f057754fc1b1a557605ab9fa6da41 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1439 Lines: 29 On Thursday 16 November 2006 01:45, Christoph Lameter wrote: > On Thu, 16 Nov 2006, Arnd Bergmann wrote: > > > - we want to be able to boot with the 'mem=512M' option, which effectively > > ? disables the memory on the second node (each node has 512MiB). > > - Each node has 8 SPUs, all of which we want to use. In order to use an > > ? SPU, we call __add_pages to register the local memory on it, so we have > > ? struct page pointers we can hand out to user mappings with ->nopage(). > > This is more like the bringup of a processor right? You need > to have the memory online before the processor is brought up otherwise > the slab cannot properly allocate its structures on the node when the > per node portion is brought up. The page allocator has similar issues. No, that's not really the issue here. The memory we're trying to add to the mem_map can not be used for kernel allocations at all and is never entered into the buddy allocator. It can only be used for applications running on an SPU itself. So the problem is not the order in which we do things, but the fact that node data structure has not been initialized, and never will be, when we add the SPU to the node. Arnd <>< - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/