Going back to last year there have been patches for adapting the Intel P-State Linux driver with support for Energy Aware Scheduling (EAS) as what began as an Arm big.LITTLE feature but since being explored for use by the Intel P-State driver for hybrid CPUs without SMT which for the moment means Lunar Lake SoCs. A new version of the patches were posted on Tuesday and likely to be the last refinement to this patch series.
Intel engineer and Linux power management subsystem maintainer Rafael Wysocki posted the new patch series for Intel P-State EAS integration for Lunar Lake. He commented on that patch series that it’s the “most likely final” version of the code and thus could be upstreamed in a forthcoming Linux kernel merge window.
The focal point of Energy Aware Scheduling for Intel P-State is the notion that:
“The underlying observation is that on the platforms targeted by these changes, Lunar Lake at the time of this writing, the “small” CPUs (E-cores), when run at the same performance level, are always more energy-efficient than the “big” or “performance” CPUs (P-cores). This means that, regardless of the scale- invariant utilization of a task, as long as there is enough spare capacity on E-cores, the relative cost of running it there is always lower.”
With the updated Intel patches, EAS is only now supported when making using of the Schedutil governor for leveraging scheduler utilization data. This Schedutil requirement aligns with other (Arm) platforms supporting EAS. THere is also improved documentation and other fixes/enhancements.
More information on EAS for Intel can be found via this new documentation patch. Those with a Lunar Lake laptop like the ThinkPad X1 Carbon G13 or ASUS Zenbook S14 and other models can find the new Intel P-State EAS patches via this patch series.
We’ll see if this gets wrapped up in time for the Linux v6.16 cycle. Once it lands I’ll be running through with some EAS power/performance benchmarks on Lunar Lake.
