From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Stevens Subject: Re: stability issue with KVM using SMP Date: Tue, 16 Sep 2008 12:46:22 +0100 Message-ID: <48CF9C8E.5040800@communitydns.net> References: <48CF6D79.6090607@communitydns.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from mk-outboundfilter-5.mail.uk.tiscali.com ([212.74.114.1]:39511 "EHLO mk-outboundfilter-5.mail.uk.tiscali.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752721AbYIPLry (ORCPT ); Tue, 16 Sep 2008 07:47:54 -0400 Received: from [192.168.250.154] (Fujitsu.james [192.168.250.154]) by home.jrcs.co.uk (8.13.6/8.12.9) with ESMTP id m8GBkNVm020726 for ; Tue, 16 Sep 2008 12:46:23 +0100 In-Reply-To: <48CF6D79.6090607@communitydns.net> Sender: kvm-owner@vger.kernel.org List-ID: Further to my previous report.. I have just noticed that, where the host is running on the dual "Quad-Core AMD Opteron(tm) Processor 2352" (family 16, model 2) the kernels in the *guest* machines (usually 2.6.26) are reporting "WARNING: This combination of AMDprocessors is not suitable for SMP." - presumably this is why my SMP isn't stable! The kernel in that host machine (2.6.26.2) does *not* report the messages. However, where the host is a single "AMD Athlon(tm) 64 X2 Dual Core Processor 4000+" (family 15, model 107) the guest kernels do not report the WARNING above - but I've not actually run any SMP guest on that host, so don't know if it would work or not. The warning seems to be due to a processor capability test in "arch/x86/kernel/smpboot.c" - "add_taint(TAINT_UNSAFE_SMP);" Its not clear to me why one guess is failing this test and the other passing, because both guests are seeing "QEMU Virtual CPU version 0.9.1", family 6, model 2 (according to "/proc/cpuinfo"). Although most kernels on the Athlon host are running 2.6.21 not 2.6.26 James