From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [BUG 2.6.32.y] Broken PV migration between hosts with different uptime, non-monotonic time? Date: Fri, 4 May 2012 14:20:13 +0100 Message-ID: <4FA3D78D.3000201@citrix.com> References: <201205041054.04079.hahn@univention.de> <4FA3B1C7.4060201@citrix.com> <201205041510.56986.hahn@univention.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201205041510.56986.hahn@univention.de> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Philipp Hahn Cc: Thomas Gleixner , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 04/05/12 14:10, Philipp Hahn wrote: > Hello David, > > On Friday 04 May 2012 12:39:03 David Vrabel wrote: >> On 04/05/12 09:54, Philipp Hahn wrote: >>> I encountered the following bug when migrating a Linux-2.6.32.54 PV >>> domain on Xen-3.4.3 between different hosts, whose uptime differs by >>> several minutes > ... >> Xen 3.4 doesn't ensure that the TSC is stable across migrates (Xen 4.0 >> does). If the host CPU has the CONSTANT_TSC bit in the Advanced Power >> Management CPUID leaf it will pass this through to the guest which makes >> the guest think the TSC is stable. >> >> Can you try this libxc patch? >> >> 8<------------------------ >> libxc: clear CONSTANT_TSC bit in Advanced Power Management CPUID leaf > > Excellent, that fixes the problem for me and makes perfect sense for me, since > AFAIK 2.6.37 also received a big TSC patch which is not part of 2.6.32.y > backport. Thanks for testing! I could never repro the migration failures. David