Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261542AbVEPRy7 (ORCPT ); Mon, 16 May 2005 13:54:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261533AbVEPRy7 (ORCPT ); Mon, 16 May 2005 13:54:59 -0400 Received: from omx3-ext.sgi.com ([192.48.171.20]:20950 "EHLO omx3.sgi.com") by vger.kernel.org with ESMTP id S261712AbVEPRyt (ORCPT ); Mon, 16 May 2005 13:54:49 -0400 Date: Mon, 16 May 2005 10:54:33 -0700 (PDT) From: Christoph Lameter To: Dave Hansen cc: Andrew Morton , linux-mm , Linux Kernel Mailing List , shai@scalex86.org, steiner@sgi.com Subject: Re: NUMA aware slab allocator V3 In-Reply-To: <1116264135.1005.73.camel@localhost> Message-ID: References: <20050512000444.641f44a9.akpm@osdl.org> <20050513000648.7d341710.akpm@osdl.org> <20050513043311.7961e694.akpm@osdl.org> <1116251568.1005.29.camel@localhost> <1116264135.1005.73.camel@localhost> 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 Content-Length: 1687 Lines: 42 On Mon, 16 May 2005, Dave Hansen wrote: > > How do the concepts of numa node id relate to discontig node ids? > > I believe there are quite a few assumptions on some architectures that, > when NUMA is on, they are equivalent. It appears to be pretty much > assumed everywhere that CONFIG_NUMA=y means one pg_data_t per NUMA node. Ah. That sounds much better. > Remember, as you saw, you can't assume that MAX_NUMNODES=1 when NUMA=n > because of the DISCONTIG=y case. I have never seen such a machine. A SMP machine with multiple "nodes"? So essentially one NUMA node has multiple discontig "nodes"? This means that the concept of a node suddenly changes if there is just one numa node(CONFIG_NUMA off implies one numa node)? > So, in summary, if you want to do it right: use the > CONFIG_NEED_MULTIPLE_NODES that you see in -mm. As plain DISCONTIG=y > gets replaced by sparsemem any code using this is likely to stay > working. s/CONFIG_NUMA/CONFIG_NEED_MULTIPLE_NODES? That will not work because the idea is the localize the slabs to each node. If there are multiple nodes per numa node then invariable one node in the numa node (sorry for this duplication of what node means but I did not do it) must be preferred since numa_node_id() does not return a set of discontig nodes. Sorry but this all sounds like an flaw in the design. There is no consistent notion of node. Are you sure that this is not a ppc64 screwup? - 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/