nova/api-guide/source/port_with_resource_request.rst
Balazs Gibizer 5af28c4de5 Support interface attach with QoS ports
The following logic is added to the ComputeManager attach_interface
flow:

* gather the resource request of the port from neutron
* query allocation candidates restricted to the current compute node
  from placement
* extend the existing allocation of the instance with one of the
  allocation candidates in placement
* update the InstancePCIRequest (if any) to ensure that the PCI claim
  only allocates VF from the PF the placement resources are allocated from
* ensure that during port binding neutron gets the RP UUID, the resources
  are allocated from, in the allocation key of the binding profile

This patch bumps the compute service version to indicate that QoS
interface attach is supported. Also the check that was so far rejected
such attach is now updated to only reject it if the compute service
version is too old.

The "scheduling" during interface attach for PCI backed ports has the
same limitation as normal scheduling for such ports. It always selects
the first allocation candidate returned by placement even if later in
the process it turns out that such allocation candidate points to a PCI
PF that has no free VFs left.

Blueprint: support-interface-attach-with-qos-ports

Change-Id: Id4684093e8bdf3b61667490443e3d2f6ed65f4b3
2021-02-11 16:43:17 +01:00

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Using ports with resource request
=================================
Starting from microversion 2.72 nova supports creating servers with neutron
ports having resource request visible as a admin-only port attribute
``resource_request``. For example a neutron port has resource request if it has
a QoS minimum bandwidth rule attached. Deleting such servers or detaching such
ports works since Stein version of nova without requiring any specific
microversion.
However the following API operations are still not supported in nova:
* Creating servers with neutron networks having QoS minimum bandwidth rule is
not supported. The user needs to pre-create the port in that neutron network
and create the server with the pre-created port.
* Attaching Neutron ports and networks having QoS minimum bandwidth rule is not
supported.
Also the following API operations are not supported in the 19.0.0 (Stein)
version of nova:
* Moving (resizing, migrating, live-migrating, evacuating, unshelving after
shelve offload) servers with ports having resource request is not yet
supported.
As of 20.0.0 (Train), nova supports cold migrating and resizing servers with
neutron ports having resource requests if both the source and destination
compute services are upgraded to 20.0.0 (Train) and the
``[upgrade_levels]/compute`` configuration does not prevent the computes from
using the latest RPC version. However cross cell resize and cross cell migrate
operations are still not supported with such ports and Nova will fall back to
same-cell resize if the server has such ports.
As of 21.0.0 (Ussuri), nova supports evacuating, live migrating and unshelving
servers with neutron ports having resource requests.
As of 23.0.0 (Wallaby), nova supports attaching neutron ports having QoS
minimum bandwidth rules.
See :nova-doc:`the admin guide <admin/port_with_resource_request.html>` for
administrative details.