Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262711AbUJ1Ab5 (ORCPT ); Wed, 27 Oct 2004 20:31:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262606AbUJ1A3S (ORCPT ); Wed, 27 Oct 2004 20:29:18 -0400 Received: from vana.vc.cvut.cz ([147.32.240.58]:25984 "EHLO vana.vc.cvut.cz") by vger.kernel.org with ESMTP id S262670AbUJ1A2L (ORCPT ); Wed, 27 Oct 2004 20:28:11 -0400 Date: Thu, 28 Oct 2004 01:27:57 +0200 From: Petr Vandrovec To: Jesper Juhl Cc: Joel Jaeggli , linux-kernel Subject: Re: Dual Opteron box, what's the optimal memory placement for the CPUs? Message-ID: <20041027232757.GB9093@vana.vc.cvut.cz> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.6+20040907i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1645 Lines: 32 On Thu, Oct 28, 2004 at 12:00:45AM +0200, Jesper Juhl wrote: > Yeah, I know they have to be installed in pairs, but I would have thought > that it would be best to have an even memory distribution so that an even > amount of local memory was available to processes executing on either CPU. > Even if Linux makes sure to execute processes on the CPU where most of > their memory is local, wouldn't a non-even distribution make more > processes prefer one CPU and thus not make the best possible use of them? > > I don't really know very much about this specific detail (which is why I > asked), and you tell me it doesn't matter, so I'll assume Linux has some > intelligent way of dealing with this that I just don't know about - That's > good enough for me, I'll trust you on that, just wanted to know for now > and the future. :-) You should also check this with your BIOS. It will be a bit unfortunate if BIOS decides to just throw away 0.5GB of your memory to make space for PCI devices, and maybe you can help BIOS a bit with right shuffling (with 3:1 it will hopefully decide to put 1GB above 4GB boundary; with 2:2 who knows; AFAIK Opteron northbridge does not allow for splitting DRAM on one node into two regions; at least I did not found how to do that). I would prefer 2:2 if both variants give you same amount of accessible memory. Best regards, Petr Vandrovec - 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/