From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH 1/1] mm: Inconsistent use of node IDs Date: Tue, 13 Mar 2007 00:19:30 +0100 References: <45F5D974.2050702@google.com> In-Reply-To: <45F5D974.2050702@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200703130019.30953.ak@suse.de> Sender: owner-linux-mm@kvack.org Return-Path: To: Ethan Solomita Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Monday 12 March 2007 23:51, Ethan Solomita wrote: > This patch corrects inconsistent use of node numbers (variously "nid" or > "node") in the presence of fake NUMA. I think it's very consistent -- your patch would make it inconsistent though. > Both AMD and Intel x86_64 discovery code will determine a CPU's physical > node and use that node when calling numa_add_cpu() to associate that CPU > with the node, but numa_add_cpu() treats the node argument as a fake > node. This physical node may not exist within the fake nodespace, and > even if it does, it will likely incorrectly associate a CPU with a fake > memory node that may not share the same underlying physical NUMA node. > > Similarly, the PCI code which determines the node of the PCI bus saves > it in the pci_sysdata structure. This node then propagates down to other > buses and devices which hang off the PCI bus, and is used to specify a > node when allocating memory. The purpose is to provide NUMA locality, > but the node is a physical node, and the memory allocation code expects > a fake node argument. Sorry, but when you ask for NUMA emulation you will get it. I don't see any point in a "half way only for some subsystems I like" NUMA emulation. It's unlikely that your ideas of where it is useful and where is not matches other NUMA emulation user's ideas too. Besides adding such a secondary node space would be likely a huge long term mainteance issue. I just can it see breaking with every non trivial change. NACK. -Andi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org