SR-IOV Port Live Migration¶

A recent change in Nova for Train release introduced the ability to live migrate instances with NUMA topology (CPU Pinning and Huge Pages also considered). This spec is to discuss and ensure support of that feature in a charm deployment.

Problem Description¶

As an operator, I would like the ability to live migrate instances with NUMA topology.

Proposed Change¶

In Nova several features depend of the internal NUMA topology object. As indicated in the problem description an operator may ask the desir of migrating such instances.

NUMA awareness when flavor is configured with hw:numa_nodes=N
CPU Pinning, when flavor is confiugred with hw:cpu_policy=dedicated
Huge Pages, when flavor is configured with hw:mem_page_size=large

The support of this improvement will be considered as tech-preview for Ubuntu 19.10/Train and production-ready for Ubuntu 18.04 LTS/Train and Ubuntu 20.04 LTS/Ussuri.

No changes are expected to any of the charms. The aim here is to validate behavior and provide additional documentations.

Alternatives¶

An operator could identify a destination host with the same characteristics as the source host and ensure that the host CPUs where the guest vCPUs are pinned on are free. Also, in case of huge pages usage, ensure the availability of the huge pages in the destination host.

By default the availibity of live migrate instances with NUMA topology is disabled in Nova but operators can enable that behavior using:

workaround/enable_numa_live_migration=True

It is to note that this option is not currently exposed in charm-nova-compute.

Implementation¶

Assignee(s)¶

Primary assignee:: Sahid Orentino Ferdjaoui <lp:sahid-ferdjaoui>

Gerrit Topic¶

Use Gerrit topic “numa-live-migration” for all patches related to this spec.

git-review -t numa-live-migration

Work Items¶

The implementation consists of the following items:

Validate behavior using NUMA awarness.
Validate behavior using CPU Pinning.
Validate behavior using Huge Pages.

Repositories¶

Any additional documentation will be considered for charm-deployment-guide.

Documentation¶

n/a

Security¶

n/a

Testing¶

n/a

Dependencies¶

See support of NUMA aware live migration spec [0].

[0] https://specs.openstack.org/openstack/nova-specs/specs/stein/approved/numa-aware-live-migration.html

SR-IOV Port Live Migration