KEP-5726: TopologyManager CPU-attached NUMA filter option

[fanzhangio]

What type of PR is this?

/kind documentation
/kind cleanup
/kind kep

What this PR does / why we need it:

Adds a draft KEP for an alpha TopologyManager policy option:

• restrict-to-cpu-numa-nodes

This option is intended to help kubelet handle large NUMA systems that expose many CPU-less NUMA nodes, such as NVIDIA GraceBlackwell / VeraRubin-class platforms.

When enabled, TopologyManager computes an effective NUMA-node set containing only NUMA nodes with CPUs attached and propagates that same view to topology-aware hint providers.

The proposal is intended to address the root issue discussed in:

• kubelet TopologyManager Stalls on Large NUMA Systems (e.g. Nvidia GB200 Compute Tray with 34 NUMA nodes) kubernetes#135541

This proposal also reworks and supersedes the earlier code-only approach discussed in:

• Support TopologyManager in Large NUMA System (NVIDIA GB200) kubernetes#135581

Which issue(s) this PR fixes:

Part of kubernetes/kubernetes#135541

Special notes for your reviewer:

Main points of the proposal:

• behavior is unchanged by default
• the option is alpha and opt-in
• the effective NUMA-node set is shared across TopologyManager, CPUManager, MemoryManager, and DeviceManager
• DeviceManager projects raw device NUMA topology onto the same effective CPU-attached NUMA-node set using NUMA distance information

There is also related broader enhancement discussion in:

• Distinguish between NUMA memory onlined as CPU memory vs. GPU memory #5726

This KEP is intentionally scoped more narrowly around a kubelet TopologyManager option.

Does this PR introduce a user-facing change?

NONE

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: fanzhangio
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[fanzhangio]

@dims @klueska

[dims]

/ok-to-test

[fanzhangio]

@ffromani Could we add this KEP to the SIG-Node agenda for discussion? I’d be happy to present it in the meeting (or follow up asynchronously over email if that’s easier) Thanks.

[ffromani]

@ffromani Could we add this KEP to the SIG-Node agenda for discussion? I’d be happy to present it in the meeting (or follow up asynchronously over email if that’s easier) Thanks.

Yes, it is 1.37 material, but the 1.37 cycle did not begun yet (we didn't finish 1.36). That said, you can present earlier to sig-node if you wish to.