Mix pinned and unpinned VMs on the same host

asked 2018-08-29 06:46:32 -0600

Is it possible to have 2 VMs instantiated on the same host, where:

  • VM1 is instantiated from the "unpinned" 2-vCPU flavor (hw:cpu_policy not set)
  • VM2 is instantiated from the "pinned" 2-vCPU flavor (hw:cpu_policy=dedicated)

and be sure that VM2's pinned vCPUs (thus physical CPUs) will not be used by VM1?

When reading the 'CPU topologies' section in the OpenStack docs it says:

Caution: Host aggregates should be used to separate pinned instances from unpinned instances as the latter will not respect the resourcing requirements of the former.

so according to above it looks it's not possible. Would like to confirm that.

Cause if you can't mix pinned and unpinned VMs on 1 host it seems to me like a huge limitation, isn't it? Asking in the telecom context where pinning is often a must for some VMs (VNFCs) and for the others not and at the same time it's desirable to have them on the same host.

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