adding compute/cpu_shared_set option

[Sahid Orentino]

In certain workload when latency is sensible, giving to users ability to move out cpu time consumed by other threads than the vCPU can be crucial.

For Rocky, Nova introduced compute/cpu_shared_set and libvirt driver uses that option to specify set of pCPUs which will be used to put emulator threads on. So guest vCPUs can be pinned on pCPUs which will be entirely dedicated for them.

After to have configured cpu_shared_set, operator will have to set hw:emulator_threads_policy:shared.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/621608

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/621608
Committed: https://git.openstack.org/cgit/openstack/charm-nova-compute/commit/?id=0cd3cee7284718a0e8fb0a4e70693d0f08f66ac9
Submitter: Zuul
Branch: master

commit 0cd3cee7284718a0e8fb0a4e70693d0f08f66ac9
Author: Sahid Orentino Ferdjaoui <email address hidden>
Date: Mon Dec 3 16:23:30 2018 +0100

    adding compute/cpu_shared_set option

    For Rocky, Nova introduced compute/cpu_shared_set and libvirt driver
    uses that option to specify set of pCPUs which will be used to put
    emulator threads on. So guest vCPUs can be pinned on pCPUs which will
    be entirely dedicated for them.

    Change-Id: I88b2afda67a91266f21d2c870a76646262488db2
    Closes-Bug: 1806434
    Signed-off-by: Sahid Orentino Ferdjaoui <email address hidden>