From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42847) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WwyGH-0003tB-Kp for qemu-devel@nongnu.org; Tue, 17 Jun 2014 14:37:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WwyG6-0000Hh-5N for qemu-devel@nongnu.org; Tue, 17 Jun 2014 14:37:37 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:43333) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WwyG5-0000Ge-OM for qemu-devel@nongnu.org; Tue, 17 Jun 2014 14:37:26 -0400 Received: from /spool/local by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 17 Jun 2014 12:37:24 -0600 Date: Tue, 17 Jun 2014 11:37:02 -0700 From: Nishanth Aravamudan Message-ID: <20140617183701.GP16644@linux.vnet.ibm.com> References: <1402905233-26510-1-git-send-email-aik@ozlabs.ru> <539EA7DD.8040306@ozlabs.ru> <20140616205150.GD8629@otherpad.lan.raisama.net> <20140617002500.GL16644@linux.vnet.ibm.com> <20140617014108.GF3222@otherpad.lan.raisama.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140617014108.GF3222@otherpad.lan.raisama.net> Subject: Re: [Qemu-devel] [PATCH 0/7] spapr: rework memory nodes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: Alexey Kardashevskiy , qemu-ppc@nongnu.org, qemu-devel@nongnu.org, Alexander Graf On 16.06.2014 [22:41:08 -0300], Eduardo Habkost wrote: > On Mon, Jun 16, 2014 at 05:25:00PM -0700, Nishanth Aravamudan wrote: > [...] > > > But you seem to claim you need 3 nodes with non-contiguous IDs. In that > > > case, which exactly is the guest-visible difference you expect to get > > > between: > > > -numa node,nodeid=0,cpus=0-7,memory=0 \ > > > -numa node,nodeid=1 \ > > > -numa node,nodeid=2,cpus=0-3,mem=1040 \ > > > -numa node,nodeid=3 \ > > > -numa node,nodeid=4,cpus=4-7,mem=1040 > > > > I guess here you'd see 5 NUMA nodes in Linux, with 0, 1 and 3 having no > > memory. > > > > > and > > > -numa node,nodeid=0,cpus=0-7,memory=0 \ > > > -numa node,nodeid=2,cpus=0-3,mem=1040 \ > > > -numa node,nodeid=4,cpus=4-7,mem=1040 > > > ? > > > > And here you'd see 3 NUMA nodes in Linux, with 0 having no memory. I > > would think the principle of least surprise means qemu doesn't change > > the topology from the user-requested one without any indicate that's > > happening? > > OK, so we are on the same page. The problem is: with your patch, both > cases above are exactly the same. That's what confused me: I thought you > wanted to implement the former, but you want the latter. > > When changing the code to allow non-contiguous node IDs, I believe we > need to differentiate those cases and implement both correctly. > Otherwise we will be forced to break compatibility in the future. Yep, I think we need at least one follow-on (or additional) patch in Alexey's series. -Nish