Intel Alder Lake-N & Raptor Lake-P CPUs To See Huge Power Management Improvements in Linux 6.2

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Linux 6.2 will provide Intel with improvement for power management on Intel Alder Lake-N and Raptor Lake-P CPUs, along with assistance with Arm hardware. The new addition to the Linux kernel adds a "normal" EPB mode, or Energy Performance Bias, that will alter the default EPB power management for the two listed Intel processor series.

The change required engineers to change the value of the EPB to "7" (it initially defaulted to "6"), which will help with the reduction of power consumed by the processor, but not directly from the core.

Engineers at Intel needed to test on the Alder Lake-N CPUs and discovered light workloads or power idling moments while running tasks like Google Meet or similar video playback and found promising results from the test. The results saved 200 mW+ in standard power savings, or 385 mW, the same in Google Meet instances. The Alder Lake-N mobile processor power savings will lower battery consumption and less heat to be pulled from the processor.

Pull changes in Linux 6.2

Split MTRR and PAT init code to accomodate at least Xen PV and TDX guests which do not get MTRRs exposed but only PAT. (TDX guests do not support the cache disabling dance when setting up MTRRs so they fall under the same category.) This is a cleanup work to remove all the ugly workarounds for such guests and init things separately (Juergen Gross)

Add two new Intel CPUs to the list of CPUs with "normal" Energy Performance Bias, leading to power savings

Do not do bus master arbitration in C3 (ARB_DISABLE) on modern Centaur CPUs

Additional updates to the Linux 6.2 kernel were a cpufreq driver focused on Apple SoC (System on Chip) processor P-States, a power capping driver called SCMI Powercap, a cpupower utility update for new support for Raptor Lake, and more hardware support with further driver extensions. Lastly, bug fixes and code cleanup were completed. You can find more information about that here.

The ACPIA and PNP codes were given new lines of code, allowing for branches 'ACPI-fan', 'ACPI-PCC, 'ACPI-misc,' and 'PNP' to be merged into Linux 6.2. Those interested in learning more can find that information on the commit here.

News Sources: Phoronix, Linux Kernel (x86/cpu), Linux Kernel (Power Management Updates), Linux Kernel (ACPI and PNP)