Comment 4 for bug 1797187

This was tested again in a brand new deployment:

  BUILD_ID="20190523T013000Z"
  Configuration: Bare Metal 2 + 2 + 2

The message is seen only when the number of huge pages required, exceeds the limit as in the following commands:

  [wrsroot@controller-0 ~(keystone_admin)]$ system host-memory-modify compute-0 0 -2M 42482
  Processor 0:No available space for 2M VM huge page allocation, max 2M VM pages: 42204

  [wrsroot@controller-0 ~(keystone_admin)]$ system host-memory-modify compute-0 0 -2M 42204
  Processor 0:No available space for 1G vswitch huge page allocation, max 1G vswitch pages: 0

It suggests a number but the 1G vswitch is not considered so by getting the 1G vswitch 1 huge page number into the equation is possible to get the max 2M / 1G VM pages that can be allocated.

      max 2M VM pages 42204 * 2048 = 86433792 < compute-0 memory
      compute-0 memory 86433792 − 1G huge page size 1048576 = 85385216 < compute-0 memory available
      compute-0 memory available 85385216 * 2048 = 41692 < max 2M VM pages

  [wrsroot@controller-0 ~(keystone_admin)]$ system host-memory-modify compute-0 0 -2M 41692

Full details:
  https://github.com/xe1gyq/starlingx/edit/master/bugs/1797187.md