From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:32957) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WzTlR-0006pj-CD for qemu-devel@nongnu.org; Tue, 24 Jun 2014 12:40:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WzTlH-0002R8-SI for qemu-devel@nongnu.org; Tue, 24 Jun 2014 12:40:09 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:36533) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WzTlH-0002R2-KO for qemu-devel@nongnu.org; Tue, 24 Jun 2014 12:39:59 -0400 Received: from /spool/local by e38.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 24 Jun 2014 10:39:58 -0600 Received: from b03cxnp07029.gho.boulder.ibm.com (b03cxnp07029.gho.boulder.ibm.com [9.17.130.16]) by d03dlp01.boulder.ibm.com (Postfix) with ESMTP id 26E3E1FF0046 for ; Tue, 24 Jun 2014 10:39:54 -0600 (MDT) Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by b03cxnp07029.gho.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s5OEaNmb9240834 for ; Tue, 24 Jun 2014 16:36:23 +0200 Received: from d03av02.boulder.ibm.com (localhost [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s5OGdswK024335 for ; Tue, 24 Jun 2014 10:39:54 -0600 Date: Tue, 24 Jun 2014 09:39:49 -0700 From: Nishanth Aravamudan Message-ID: <20140624163949.GH4323@linux.vnet.ibm.com> References: <20140623193310.GD4323@linux.vnet.ibm.com> <20140624093348.094e6176@nial.usersys.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140624093348.094e6176@nial.usersys.redhat.com> Subject: Re: [Qemu-devel] [RFC PATCH] numa: enable sparse node numbering List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Igor Mammedov Cc: Alexey Kardashevskiy , qemu-devel@nongnu.org, Eduardo Habkost , "Michael S. Tsirkin" On 24.06.2014 [09:33:48 +0200], Igor Mammedov wrote: > On Mon, 23 Jun 2014 12:33:10 -0700 > Nishanth Aravamudan wrote: > > > Add a present field to NodeInfo which indicates if a given nodeid was > > present on the command-line or not. Current code relies on a memory > > value being passed for a node to indicate presence, which is > > insufficient in the presence of memoryless nodes or sparse numbering. > > Adjust the iteration of various NUMA loops to use the maximum known NUMA > > ID rather than the number of NUMA nodes. > Why would you need sparse numbering? We already see this in practice under PowerVM on ppc. This would allow qemu/KVM to emulate the same behaviors (which often lead to bugs/testing of underused code-paths in the kernel). Also, sparse numbering is explicitly allowed by qemu already but doesn't work at all as expected, at least to me. That is, if I specify various node IDs, the nodes are allocated linearly in qemu and the NUMA node IDs in Linux don't correspond to the command-line. Further, the location of CPUs/memory doesn't correspond to the nodes requested by the user. > What task exactly are you trying to solve? I would like to be able to leverage qemu's command-line to reproduce the NUMA topology seen under PowerVM. I'll send v3 with a better changelog and a few changes from Hu Tao. Thanks, Nish