AMD P-State Preferred Core Support For Linux Tried A 13th Time

One of the features sadly not having made it in time for the Linux v6.8 kernel merge window is the AMD P-State Preferred Core support. This is about being able to properly communicate to the kernel and scheduler about "preferred cores" such as cases of some CPU cores having higher maximum frequencies or better performance characteristics than others. This is becoming more important with AMD Ryzen processors beginning to see a combination of Zen 4 and Zen 4C cores and other cases like AMD 3D V-Cache enabled processors where some cores would be preferred over others for performance sensitive work.

AMD for months now has been working on this P-State Preferred Core support for being able to expose to the operating system processor cores that have a higher maximum frequency or otherwise more preferred over other cores. The platform communicates these core preferences via the ACPI Collaborative Processor Performance Control (CPPC) data.

The AMD P-State Preferred Core support for Linux over the course of the patch history has adapted to be able to support dynamic core rankings based on workload and perform conditions such as around thermal and power changes. In turn the AMD preferred core preferences are exposed to the kernel's scheduler so that they will be favored during task scheduling.

Sent out today was the 13th iteration of the AMD Preferred Core patches for the Linux kernel. There's been various small updates and some other basic patch maintenance. Nothing too major though so hopefully this will cross the finish line soon: it's too late now for Linux v6.8 but perhaps we'll see this sought after feature ready for v6.9 in the spring. Those wanting to try out the v13 Linux patches can find them on the kernel mailing list.