From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chao Peng Subject: Re: Crash in set_cpu_sibling_map() booting Xen 4.6.0 on Fusion Date: Fri, 27 Nov 2015 10:11:55 +0800 Message-ID: <20151127021155.GF17000@pengc-linux.bj.intel.com> References: <564F030C02000078000B70A6@prv-mh.provo.novell.com> <5652F61A02000078000B7B64@prv-mh.provo.novell.com> <56544B5502000078000B84F4@prv-mh.provo.novell.com> <20151125074830.GC17000@pengc-linux.bj.intel.com> <565587A602000078000B8D55@prv-mh.provo.novell.com> <5656C7A602000078000B93E3@prv-mh.provo.novell.com> Reply-To: Chao Peng Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <5656C7A602000078000B93E3@prv-mh.provo.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich , Ed Swierk Cc: Andrew Cooper , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On Thu, Nov 26, 2015 at 12:49:42AM -0700, Jan Beulich wrote: > >>> On 26.11.15 at 00:27, wrote: > > A few more data points: I also tested Xen 4.6 on VMware ESXi 5.5, and > > it yields similar results. Not surprising, since Fusion uses basically > > the same virtualization engine. > > > > However, ESXi offers many more choices of number of processors, number > > of cores, hyperthreading, etc. The weird processor ID assignment (0, > > 2, 4, 6, ...) occurs only with 4 or 8 processors, 1 core per socket, > > and no hyperthreading. If I change any of these parameters, the > > processor IDs become sequential. > > > > It appears in the 4- and 8-processor cases, VMware is emulating > > something like a Xeon E7340: > > https://github.com/deater/test_proc/blob/master/x86_64/x86_64.intel.6.15.11. > > xeon_e7340 > > > > In fact someone asked a question about running Xen on this platform > > way back when: > > http://lists.xenproject.org/archives/html/xen-users/2008-05/msg00691.html > > > > Others of similar vintage assign processor IDs 0 and 3 on a > > 2-processor system: > > https://www.centos.org/forums/viewtopic.php?t=30255 > > > > or even 0 and 6: > > http://serverfault.com/questions/302429/interpreting-cpuinfo > > > > So there are real hardware platforms with non-sequential processor > > IDs. They are quite ancient and don't support CAT, but that doesn't > > rule out the possibility of a newer or future platform behaving > > similarly. > > Not supporting CAT is not a criteria, since the socket data setup > happens unconditionally. However (and as said before), non- > sequential processor IDs are fine. Non-sequential socket IDs are > what is problematic. I asked non-sequential socket ID problem internally but I don't know if I can get a clear answer in the end, please just stay tuned for a while. Thanks, Chao