AMD Zen1/Zen2/Zen3 PowerCap RAPL Support Queued For Linux 5.11
Written by Michael Larabel in AMD on 16 November 2020 at 03:36 AM EST. 9 Comments
AMD --
The work reported on back in October for RAPL PowerCap patches for AMD Zen CPUs from Zen 1 through Zen 3 are set to arrive with Linux 5.11 in early 2021.

This work led by Google engineers allow the AMD Family 17h/19h RAPL (Runtime Average Power Limiting) support within the Linux kernel's power-capping framework in the PowerCap driver.

Those unfamiliar with Linux's power-capping framework can see the kernel.org documentation. To user-space this provides a consistent interface for the power information now for both Intel/AMD processors.

Up to now the PowerCap driver has been Intel-only but extended by Google to support AMD CPUs in the form of Zen 1 and newer. This patch has the Zen 1 / Zen 2 support while a follow-up patch adds the support for Family 19h (Zen 3) given the MSRs are identical to the earlier Zen CPUs.

These patches have been queued into the Linux power management "-next" branch making them Linux 5.11 material for when that merge window opens in December.

Along related lines and for those not aware, Linux 5.8 added the "AMD_Energy" driver for exposing CPU energy information to user-space via the hardware monitoring (HWMON) interfaces. Though at the moment that driver does not yet support Zen 3 processors.
Related News
About The Author
Author picture

Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

Popular News This Week