Cumulative CPU time not implemented

[Eric Fried]

The nova-powervm driver claims 'complete' for:

[operation.get-guest-info]
title=Guest instance status
status=mandatory
notes=Provides a quick report on information about the guest instance,
  including the power state, memory allocation, CPU allocation, number
  of vCPUs and cummulative CPU execution time. As well as being
  informational, the power state is used by the compute manager for
  tracking changes in guests. Therefore this operation is considered
  mandatory to support.

However, "cumulative CPU execution time" would be reported via InstanceInfo.cpu_time_ns, which is currently set to 0 and never updated [1].

There's a couple of questions here:
- Is this attribute mandatory to claim 'complete' for the operation?
- To what level is it even possible for us to calculate this?
  - Does PCM report a total-since-birth for an LPAR?
  - Does that total get reset at events like LPAR reboot? Live migration? REST server restart?

Need to look at how the other drivers handle this and make some attempt at parity.

[1] https://github.com/openstack/nova-powervm/blob/0b91811519ce3e9d07b29412949a6fed97837835/nova_powervm/virt/powervm/vm.py#L170

[Matthew Edmonds (edmondsw)]

https://github.com/openstack/nova/commit/5db9389c01b0cb6eeacf57c22550876ffcd1a87c removes cpu_time_ns from nova, so we should just need to cleanup nova-powervm to no longer set that at all (or the other things that nova commit removed).

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/540507

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/540507
Committed: https://git.openstack.org/cgit/openstack/nova-powervm/commit/?id=a4e0721c6b307ab0046c3314aaa2b691ff8053df
Submitter: Zuul
Branch: master

commit a4e0721c6b307ab0046c3314aaa2b691ff8053df
Author: Matthew Edmonds <email address hidden>
Date: Fri Feb 2 14:13:36 2018 -0500

    Trim the fat from InstanceInfo

    Nova removed several fields from InstanceInfo that were not being
    used [1]. This copies our corresponding in-tree driver changes to
    the out-of-tree driver.

    [1] 5db9389c01b0cb6eeacf57c22550876ffcd1a87c

    Closes-Bug: #1695924
    Change-Id: I865d9177329294f555dfda14f2ffd85bd022db56