From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC] allow multi-core guests: introduce cores= option to -cpu Date: Sat, 04 Jul 2009 18:25:16 +0300 Message-ID: <4A4F745C.8010001@redhat.com> References: <1246632116-31366-1-git-send-email-andre.przywara@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: anthony@codemonkey.ws, qemu-devel@nongnu.org, kvm@vger.kernel.org To: Andre Przywara Return-path: Received: from mx2.redhat.com ([66.187.237.31]:55090 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751117AbZGDPZT (ORCPT ); Sat, 4 Jul 2009 11:25:19 -0400 In-Reply-To: <1246632116-31366-1-git-send-email-andre.przywara@amd.com> Sender: kvm-owner@vger.kernel.org List-ID: On 07/03/2009 05:41 PM, Andre Przywara wrote: > Hi, > > currently SMP guests happen to see vCPUs as different sockets. > Some guests (Windows comes to mind) have license restrictions and refuse > to run on multi-socket machines. > So lets introduce a "cores=" parameter to the -cpu option to let the user > specify the number of _cores_ the guest should see. > > This patch has not been tested with all corner cases, so I just want to > hear your comments whether > a) we need such an option and > b) you like this particular approach. > > Applying this qemu.git patch to qemu-kvm.git fixes Windows SMP boot on > some versions, I successfully tried up to -smp 16 -cpu host,cores=8 with > WindowsXP Pro. > > I thought of using -smp [processors=]2,cores=4,threads=2 (for a total of 16 threads), but I think it makes more sense with -cpu. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.