Hi Paul, yes, this is exactly what we are observing. Thanks for the bugzilla pointer.
We now also opened a ticket through the RedHat support. thanks, Belmiro On Mon, Oct 9, 2017 at 12:37 PM, Paul Browne <pf...@cam.ac.uk> wrote: > Hello Belmiro, > > We ran into this issue recently, similarly upgrading a RHEL7.3 OpenStack > Platform Overcloud to RHEL7.4 and in the process upgrading libvirtd. > > For instances that were spawned prior to this upgrade, we see the CPU > flags [1] , but for new instance workload the CPU flags [2]. Notably the > CMT=disabled flag is present in [1] but absent in [2] > > This similarly prevents live migration of the older spawned instances, as > the CMT=disabled flag is rejected. > > A RH bugzilla [3] was opened on the issue which attracted a lot of really > good contributions from libvirt maintainers. The one sure-fire workaround > we'd found is just to cold-boot the instance again, starting it under the > new libvirtd. But from that BZ there is also a slightly more hack-ish > workaround to hand-edit the running domain XML and clear the offending CMT > flag (comment 12 on that BZ). > > Hope this helps some, > > Thanks, > Paul Browne > > [1] https://pastebin.com/JshWi6i3 > [2] https://pastebin.com/5b8cAanP > [3] https://bugzilla.redhat.com/show_bug.cgi?id=1495171 > > On 9 October 2017 at 04:59, Belmiro Moreira <moreira.belmiro.email.lists@ > gmail.com> wrote: > >> Hi, >> the CPU model that we expose to the guest VMs varies considering the >> compute node use case. >> We use "cpu_mode=host-passthrough" for the compute nodes that run batch >> processing VMs and "cpu_mode=host-model" for the compute nodes for service >> VMs. The reason to have "cpu_mode=host-model" is because we assumed that >> new CPUs (in the libvirt map) will continue to support previous features >> allowing for live migration when we need to move the VMs to a new CPU >> generation. >> >> We recently upgraded from CentOS7.3 (libvirt 2.0.0) to CentOS7.4 (libvirt >> 3.2.0) and noticed that now libvirt maps a slightly different CPU for the >> guests. For example, still "Haswell no-TSX" but no mention to the feature >> "cmt". This blocks suspended VMs to restore and live migrate. >> >> Has anyone experienced this same problem? >> >> We are thinking in few solutions but none of them are nice (downgrade >> libvirt? hard reboot instances? ...) >> >> thanks, >> Belmiro >> >> _______________________________________________ >> OpenStack-operators mailing list >> OpenStack-operators@lists.openstack.org >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators >> >> > > > -- > ******************* > Paul Browne > Research Computing Platforms > University Information Services > Roger Needham Building > JJ Thompson Avenue > University of Cambridge > Cambridge > United Kingdom > E-Mail: pf...@cam.ac.uk > Tel: 0044-1223-746548 > ******************* >
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