This mirrors the 'hw_vif_multiqueue_enabled' image metadata property.
Providing a way to set this via flavor extra specs allows admins to
enable this by default and easily enable it for existing instances
without the need to rebuild (a destructive operation).
Note that, in theory at least, the image import workflow provided by
glance should allows admins to enable this by default, but the legacy
image create workflow does not allow this and admins cannot really
control which API end users use when uploading their own images.
Also note that we could provide this behavior using a host-level
configuration option. This would be similar to what we do for other
attributes such as machine type ('hw_machine_type' image meta prop or
'[libvirt] hw_machine_type' config option) or pointer model
('hw_pointer_model' image meta prop or '[compute] pointer_model' config
option) and would be well suited to things that we don't expect to
change, such as enabling multiqueue (it's a sensible default). However,
we would need to start storing this information in system_metadata, like
we do for machine type (since Wallaby) to prevent things changing over
live migration. We have also started avoiding host-level config options
for things like this since one must ensure that the value configured are
consistent across deployments to behavior that varies depending on the
host the guest is initially created on.
Change-Id: I405d0324abe32b31a434105cf2c104876fe9c127
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>
f42fb1241b