From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andre Przywara Subject: Re: Ping: c/s 20526 (tools: avoid cpu over-commitment if numa=on) Date: Wed, 13 Jan 2010 15:24:35 +0100 Message-ID: <4B4DD7A3.70701@amd.com> References: <4B4D8F1C02000078000299EC@vpn.id2.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4B4D8F1C02000078000299EC@vpn.id2.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jan Beulich Cc: xen-devel@lists.xensource.com, Keir Fraser List-Id: xen-devel@lists.xenproject.org Jan Beulich wrote: > Andre, > > I'm afraid this change isn't really correct: > >> + cores_per_node = info['nr_cpus'] / info['nr_nodes'] >> + nodes_required = (self.info['VCPUs_max'] + cores_per_node - 1) / cores_per_node > > Simply using cores_per_node (as calculated here) as a divisor is bound > to cause division-by-zero issues, namely when limiting the number of > CPUs on the Xen command line (maxcpus=). I'm not sure though, what > a reasonable solution to this might look like, since cores-per-node is > a meaningless thing in an artificial setup like this, and may also be > meaningless in asymmetric configurations. So perhaps we really need > to iterate over nodes while summing up the number of CPUs they > have until the number of needed vCPU-s was reached. Thanks for the heads-up. I have created a better patch basically doing what you described, actually it is even more elegant than the original version. I am about to test it and will send it out as soon as the testing is finished. Regards, Andre. -- Andre Przywara AMD-Operating System Research Center (OSRC), Dresden, Germany Tel: +49 351 448 3567 12 ----to satisfy European Law for business letters: Advanced Micro Devices GmbH Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen Geschaeftsfuehrer: Andrew Bowd; Thomas M. McCoy; Giuliano Meroni Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen Registergericht Muenchen, HRB Nr. 43632