Linux 6.2 Will Help With Power Savings For Intel Alder Lake N & Raptor Lake P
Before even getting to the PM/ACPI proper material for the Linux 6.2 merge window, the x86/cpu pull has a change worth mentioning. That change is adding Intel Alder Lake N and Raptor Lake P models to having a "normal" Energy Performance Bias (EPB).
The change to the Intel EPB code adjusts the default Energy Performance Bias hint for power management to Intel's recommended default for the ADL-N and RPL-P processors. By bumping the default EPB value from 6 to 7 for these models, it reduces the uncore power consumption. Testing on Alder Lake N by Intel engineers was found that for idling to light workloads like running Google Meet or VP9 video playback this EPB tweak was of benefit. They generally found 200mW+ in power-savings or 385 mW in power-savings while using Google Meet. For mobile ADL-N processors, the power savings can be significant for thermal and battery life reasons. Under full load the performance or power consumption is expected to be unaffected.
The Intel EPB default for Intel ADL-N and RPL-P is now properly adjusted with Linux 6.2.
Meanwhile on Monday Intel's Rafael Wysocki sent in the power management pull request. Most notable there is the Apple M1/M2 CPUFreq driver being merged for supporting CPU frequency scaling on that Apple Silicon for its P-State handling. There is also an ARM SCMI PowerCap driver merged too.
Intel P-State with Linux 6.2 meanwhile adds support for running with Xeon Scalable 4th Gen "Sapphire Rapids" processors when in the no-HWP (Hardware P-State) mode. Intel also added initial Emerald Rapids support to the intel-uncore-freq driver this cycle. They also added the intel-rapl library, powercap-info command, and RAPL monitor into the cpupower code contained within the Linux kernel source tree.
Over with the ACPI pull request is updating of the ACPICA code, various quirks, and different fixes.
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