One of the patch series that sadly was not ready in time for the Linux 6.10 merge window and thus will need to wait a few months for at least the next kernel is enabling AMD Fast CPPC support for Zen 4 processors. Fast CPPC aims to allow the processor to deliver higher performance at the same power consumption.

Earlier this year I wrote about AMD's work on [1]enabling Fast CPPC for Linux as a feature new to existing Zen 4 processors. The AMD P-State CPU frequency scaling driver makes use of the ACPI Collaborative Processor Performance Control (CPPC) data for describing performance scales and attributes on a per-CPU basis and in turn the kernel requesting desired performance levels. With some AMD processors beginning with current Zen 4 models, there is the notion of "fast CPPC". The Fast CPPC feature when indicated by a CPU bit allows for a faster CPPC loop thanks to architectural enhancements. In turn leveraging AMD Fast CPPC can make for higher performance at the same power level.

Posted this weekend were the [2]AMD Fast CPPC v4 patches now out for kernel review. The patch series simply sums it up as:

"Some AMD Zen 4 processors support a new feature FAST CPPC which allows for a faster CPPC loop due to internal architectural enhancements. The goal of this faster loop is higher performance at the same power consumption."

The patches when tested on an AMD Ryzen 7 7840HS have pointed to Fast CPPC allowing 0~2% better performance while the performance-per-Watt can see as much as a ~6% benefit.

Here's to hoping this AMD Fast CPPC support for the AMD P-State driver will be ready in time for the Linux 6.11 kernel later in the summer. [3]AMD Core Performance Boost support is another feature also still undergoing review for the AMD P-State Linux driver.



[1] https://www.phoronix.com/news/AMD-Fast-CPPC-Linux-Patches

[2] https://lore.kernel.org/linux-pm/e717feea3df0a178a9951491040a76c79a00556c.1716649578.git.Xiaojian.Du@amd.com/

[3] https://www.phoronix.com/news/AMD-Core-Perf-Boost-Per-CPU