From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LCk0q-0002Qm-Ux for qemu-devel@nongnu.org; Tue, 16 Dec 2008 19:11:41 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LCk0q-0002QG-7h for qemu-devel@nongnu.org; Tue, 16 Dec 2008 19:11:40 -0500 Received: from [199.232.76.173] (port=46078 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LCk0q-0002QB-41 for qemu-devel@nongnu.org; Tue, 16 Dec 2008 19:11:40 -0500 Received: from rn-out-0910.google.com ([64.233.170.191]:27664) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1LCk0p-0004kA-Qt for qemu-devel@nongnu.org; Tue, 16 Dec 2008 19:11:39 -0500 Received: by rn-out-0910.google.com with SMTP id 56so2872146rnw.8 for ; Tue, 16 Dec 2008 16:11:38 -0800 (PST) Message-ID: <494843B4.6090705@codemonkey.ws> Date: Tue, 16 Dec 2008 18:11:32 -0600 From: Anthony Liguori MIME-Version: 1.0 References: <4947B819.9090307@amd.com> <49481AAD.5060501@codemonkey.ws> <49483F56.7020703@amd.com> In-Reply-To: <49483F56.7020703@amd.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [PATCH 3/8] v2: add info numa monitor command Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andre Przywara Cc: qemu-devel@nongnu.org, Avi Kivity Andre Przywara wrote: > Anthony Liguori wrote: > >> So the current code limits us to 64-cpus? That's a pretty serious >> limitation IMHO. > I know, but I was hoping that a simpler patch would be easier to > merge. So I am happy to fix it later and lift this restriction. > I searched for some kind of variable length bitmap type (like Linux' > cpu_set_t) already being used in QEMU, but couldn't find anything > appropriate. Do you know something? If you look at the glibc cpu_set_t > implementation (in bits/sched.h), you surely want to make this a > separate patch. I don't know that there's anything immediately obvious to use. >> I think that strongly suggests we're using the wrong structures for >> node_to_cpus--especially to be in the BIOS FW interface. > Ok, this could be a point, but is this BIOS FW interface really a > stable interface we cannot change later easily? IMHO this is QEMU (and > derived projects) only, which always provide a matching BIOS anyway. > > What about if I prepare the BIOS FW interface for future expansion and > stick to the current uint64_t type for now? Please make the BIOS FW interface and the BIOS patch able to handle > 64 cpus. It's relatively painful to get stuff merged into Bochs and sync the BIOS. I don't want to have to go through that again in the near future once Jes gets wind of the fact that you're limiting us to 64 cpus ;-) I can live with QEMU being limited to 64 cpus for now. > Regards, > Andre. > > And by the way: 64 core machines are _not_ common today, especially > not when hosting pure QEMU :-) It all depends on your perspective. At any rate, the Core i7's reintroduce hyperthreading so you're looking at 16-way CPUs once the octal cores are released. I'm not sure the time frame, but I think 12-core CPUs are in the near future two from both Intel and AMD. A single 4-socket board will be 64-way. A multi-node system will easily be > 64-way. This isn't long term future things, this is stuff that'll be relatively common next year. Regards, Anthony Liguori