cpu-model only works with the model it is set

[Ashley Lai]

Our playground environment has 2 cpu models for compute nodes.
IvyBridge-IBRS and SandyBridge-IBRS

When setting cpu-model to SandyBridge-IBRS, creating instances work only on SandyBridge-IBRS hosts and failed on IvyBridge-IBRS hosts and vice versa (when setting it to IvyBridge-IBRS).

My understanding is setting cpu-model to the oldest model should work for all hosts.

[Aurelien Lourot (aurelien-lourot)]

Hi and thanks for reporting. In the charm we only pass the cpu model to nova via nova.conf. Know values are described here [0]. In this document it is said that if your values aren't known, the 'cpu_compare' method will be used and is described here [1]. This document [2] indeed states that if you chose 'custom' for the CPU mode, the comparison will be based on age.

Did you set the 'cpu-mode' to 'custom' per juju config?

0: https://wiki.openstack.org/wiki/LibvirtXMLCPUModel
1: https://www.berrange.com/posts/2010/02/15/guest-cpu-model-configuration-in-libvirt-with-qemukvm/
2: https://docs.openstack.org/nova/train/admin/configuration/hypervisor-kvm.html#custom

[Launchpad Janitor (janitor)]

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