From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim M Subject: Re: [Bug 1759] Xen 4.0.1 live migration/restore over-writes new hypervisor's boot-time record Date: Wed, 13 Apr 2011 12:31:57 -0700 Message-ID: <20110413193156.GC6445@lumida.com> References: <20110413162545.GA29815@lumida.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Wed, Apr 13, 2011 at 07:34:01PM +0100, Keir Fraser wrote: > The fix is still there, albeit in a modified form since the restore code has > changed quite a bit since Xen 3. Can you reliably repro this, with any PV > guest? > > -- Keir This is 100% reproducible. Every time I migrate from a host with an uptime longer than the target host, the VM has a clock/time freeze for however long the uptime difference is. Migrating from a host with shorter uptime to a host with longer has no problem. As a demonstration, I have two dom0 hosts that have roughly 6 minutes difference in uptime. I started a guest VM on the dom0 host with a longer uptime then SSH'd to the guest and ran this command: while true ; do date ; sleep 5 ; done Next I initiated a live migration and this is what the output of the command looks like (with commentary added): Wed Apr 13 12:07:48 PDT 2011 Wed Apr 13 12:07:53 PDT 2011 Wed Apr 13 12:07:58 PDT 2011 Wed Apr 13 12:08:03 PDT 2011 [ migration happens here and SSH to the guest "freezes" for about 6 min ] Wed Apr 13 12:13:55 PDT 2011 Wed Apr 13 12:14:00 PDT 2011 Wed Apr 13 12:14:05 PDT 2011 I have only tried Ubuntu 10.04.2 guests running the 2.6.32 and 2.6.35 server kernel packages but, as mentioned, this happens every time.