[sig-scheduling] Code Freeze Exception Request: Fast host-scoped interpod affinity

[Tetiana Khotiaintseva]

Hello Release Team,

I'd like to request a  7 calendar day code freeze exception for the following enhancement.

Enhancement name: Fast Host-Scoped Inter-Pod Affinity and Anti-Affinity 

Enhancement status: Alpha 

SIG: SIG Scheduling 

k/enhancements issue (KEP): None. SIG Scheduling maintainers agreed a KEP would be an overkill since the changes are conceptually straightforward and well isolated behind a feature gate. 

Tracking issue: https://github.com/kubernetes/kubernetes/issues/138314PR: https://github.com/kubernetes/kubernetes/pull/138198

Additional time needed: 7 calendar days (due Wednesday, July 29)

Reason this enhancement is critical: It brings a massive performance optimization to the interpodaffinity plugin. It avoids expensive O(N*M) cluster-wide scans for the common kubernetes.io/hostname topology by introducing a fast-track evaluation path. Scheduling throughput is 161.24% faster (p90) in the heaviest performance test. This performance improvement is critical for Cluster Autoscaler, which simply doesn't work on large clusters if interpod (anti)affinity is used.

Reason the extension is needed: The implementation is fully complete and in the final active review stage. We need a little more time to gather the final LGTM and Approvals from the maintainers.

Risks from adding code late: Very low. The changes are strictly guarded by the InterPodAffinityHostnameFastPath feature gate, which is an Alpha feature disabled by default.

Risks from cutting the enhancement: Delaying a fully implemented and heavily reviewed performance improvement that would greatly benefit the community.

Thank you, 

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Tetiana Khotiaintseva

SWE @ GKE Cluster Autoscaler

Google Poland

[Dominik Marcinski]

+1 The changes were in review under SIG for a long time, but due to higher priority efforts, they were not getting enough attention.

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[Kensei Nakada]

+1

2026年7月21日(火) 23:58 'Tetiana Khotiaintseva' via sig-scheduling <sig-sch...@kubernetes.io>:

[Dipesh Rawat]

Hi all,

After reviewing the request and the discussion in the referenced Slack thread [0], the Release Team is APPROVING this exception request for a 3 calendar day extension rather than the originally requested 7 days.

Based on the 3 calendar day extension, the updated deadline for this KEP is: Saturday, 25th July 2026 (Anywhere on Earth) / Sunday, 26th July 2026, 12:00 UTC.

Please note that all remaining reviews and pending work needs to be completed within this extension. Otherwise, this will need to be deferred to a future release.

If you need any clarification, please feel free to reach out to us in the #sig-release Slack channel.

Thanks,
Dipesh Rawat
v1.37 Release Lead

[0]: https://kubernetes.slack.com/archives/C2C40FMNF/p1784738016003099