AMD P-State EPP Patches Spun An 8th Time For Helping Out Linux Performance & Efficiency

Written by Michael Larabel in AMD on 19 December 2022 at 05:27 AM EST. 36 Comments
AMD kicked off Christmas week by posting an eighth version of their P-State EPP driver patches for implementing the AMD Energy Performance Preference handling within their recent processors/SoCs for software to hint a performance or energy efficiency hint. P-State EPP can address some of the shortcomings with AMD's original P-State driver implementation merged nearly a year ago and has been showing good results in numbers posted by AMD engineers.

Over the past year and few months AMD Linux engineers have been working a lot on the AMD P-State driver code for a proper CPU frequency scaling driver for Zen 2 and newer hardware that supports ACPI CPPC. AMD P-State aims to deliver better performance and power efficiency than the generic ACPI CPUFreq driver used on AMD processors to this point.

Benchmark numbers by AMD show P-State EPP addressing some of the gaps with the initial P-State driver.

The AMD P-State driver that premiered in Linux 5.17 showed at times to have some performance regressions compared to ACPI CPUFreq but the P-State EPP functionality will hopefully clear that up. AMD engineers also recently started working on a P-State Guided Autonomous Mode too.

AMD P-State EPP sadly isn't ready for Linux 6.2 but that delay allowed time for a v8 patch-set to be published. This morning's AMD P-State EPP v8 patches make various low-level code changes, address other upstream review feedback, remove the I/O wait boost code, and other small changes. Nothing too dramatic and from the sounds of prior LKML discussions, it sounds like the AMD P-State EPP code will likely soon be picked up by the power management subsystem's "for-next" branch for additional exposure ahead of the Linux 6.3 cycle.

Once this AMD P-State EPP code settles down ahead of mainline I'll be around with some benchmarks for this CPU frequency scaling driver on AMD Ryzen desktops/laptops and EPYC server platforms.
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Michael Larabel is the principal author of 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 automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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