AMD Ryzen PCs May See More Power Savings Out-Of-The-Box With Linux 6.14

AMD Ryzen systems with the upcoming Linux 6.14 kernel may see increased power savings out-of-the-box due to an AMD P-State driver change queued up as part of the new power management code for this next version of the Linux kernel.

First talked about a few weeks back for the AMD P-State patches for Linux 6.14 is the ability to set a different EPP (Energy Performance Preference) policy for EPYC and Ryzen processors.

This stems from a bug report suggesting "balance_performance" for Ryzen CPUs by default rather than "performance" as commonly used by default for both Ryzen and EPYC processors. The bug report argued:

I would really love AMD to consider setting energy_performance_preference to balance_performance at least for laptops.

By default amd-pstate overshoots frequencies and makes power consumption significantly higher for simple tasks such as watching YouTube videos with HW acceleration turned on.

Here's a simple comparison:

Watching a VP9 1080p YouTube video in Firefox with HW acceleration turned on:

performance balance_performance
Watts 14W 7W
CPU frequency 5000MHz 3000MHz

In terms of sustained performance for tasks that require full CPU use, the difference is negligible.

After internal discussions at AMD, the developers agreed for Ryzen processors the "balance_performance" default is probably sensible while keeping "performance" for the powerful EPYC server processors.

AMD Linux engineer Mario Limonciello commented with the patch allowing for different default EPP policies between EPYC and Ryzen:

"For Ryzen systems the EPP policy set by the BIOS is generally configured to performance as this is the default register value for the CPPC request MSR.

If a user doesn't use additional software to configure EPP then the system will default biased towards performance and consume extra battery. Instead configure the default to "balanced_performance" for this case."

That patch is part of the AMD P-State changes submitted for the Linux 6.14 power management code and have already made it into the PM subsystem's "next" branch ahead of the Linux v6.14 merge window opening in late January.