Goal: 

As a developer, I want one scale testing scenario by using the fake virt driver, so I can build up a CI job for multiple scenarios and eventually fine tune the thread pool sizes of various nova services running in threading mode.

Acceptance Criteria:

• A blog post exists describing how the CI job works
• A blog post or other form of test report exists that details what measurement was done and what suggestions we have about the scaling of our thread pools or other algorithms.
• If the scale testing finds bugs then those bugs are reported upstream.
• If the scale testing suggests different pool size defaults then those opened as bugs as well upstream.
• All services that can run in threading is covered by reconfiguring it to threading. (Add conductors)

The test report should contain:

• the description of the test scenario
• baseline performance measurement (runtime, memory usage) of those scenarios with eventlet
• performance measurement of the scenarios with threading mode enabled on all nova services that supports them

The single scenarios to cover:

• multi cell and multi compute setup checking scheduling performance (scheduler scatter gather) via booting VMs in parallel.

Known limitations:

• Using fake driver means we cannot test nova-compute - libvirt interactions.

This story complements but does not replaces scale testing with real hardware

• https://issues.redhat.com/browse/RHOSSTRAT-788

This story was split out of OSPRH-19526 to cover the CI job setup with a single rally scenario.