Cluster Idling

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" summary

Describes an extension to CPU idle using the generic PM domain and a new genpd governor that chooses cluster-wide idle states by aggregating per‑CPU timers and a Last‑Man‑Standing reference; deployed against PCI firmware backends and tested on HiKey and Dragonboard plus a MediaTek tryout. A v13 series of patches sits on the mailing list (core four patches still awaiting merge) and uses per‑CPU flags, brief spinlock checks and firmware-side handling to avoid long busy‑loops; suspend‑to‑idle and ktime_get overheads remain as known limits.

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" chapters (12)

1. 0:00Introduction to cluster idling
2. 2:17Why cluster idling is needed
3. 7:50Current solution and PCI firmware
4. 11:24Limitations and race conditions
5. 21:30OS vs platform coordinated modes
6. 28:02Suspend to idle challenges
7. 31:28Optimizing timekeeping in idle paths
8. 42:34Time resolution trade-offs
9. 45:52Simplifying PM core for CPUs
10. 47:24Next steps for governor improvements
11. 51:41Hierarchy and state selection
12. 55:55Q&A and closing remarks