AMD Ryzen 9 7950X P-State/CPUFreq Frequency Scaling Performance On Linux

Written by Michael Larabel in Software on 10 October 2022. Page 1 of 5. 25 Comments

For those wondering the difference using the aging ACPI CPUFreq driver or the newer AMD P-State CPU frequency scaling drivers make for modern Ryzen 7000 "Zen 4" desktops, here are some CPUFreq/P-State driver tests using the Ryzen 9 7950X as well as testing the various governor options and looking at the impact on the CPU power consumption, peak frequency, and thermals too.

This round of testing is mainly intended for reference purposes if you are a new owner of the recently launched AMD Ryzen 7000 series processors and are wondering about the CPU frequency scaling driver/governor options for the best Linux desktop experience and performance.

With the AMD Ryzen 9 7950X running at stock speeds (the clock differences shown in the automated system table just come down to reporting differences between drivers) and using the Linux 6.0 kernel, the following configurations were tested:

- amd-pstate schedutil
- amd-pstate performance
- acpi-cpufreq schedutil
- acpi-cpufreq ondemand
- acpi-cpufreq performance

Traditionally the default among Linux distributions with AMD CPUs has been using acpi-cpufreq ondemand out-of-the-box, though some newer Linux distributions have shifted to acpi-cpufreq for schedutil in making use of Linux kernel scheduler utilization data. Meanwhile on the very newest Linux distributions, including the likes of Ubuntu, AMD processors of Zen 2 and newer are often finding amd-pstate schedutil as the default. The amd-pstate driver was mainlined by AMD last year and continues to be improved upon. There is also the new AMD P-State EPP driver on top of that, but that driver isn't being tested today with not being mainlined until at least Linux 6.2. And then the amd-pstate and acpi-cpufreq drivers with the "performance" governor were tested for showing the maximum potential.

A wide range of Linux benchmarks with the Ryzen 9 7950X were carried out for seeing the impact on these Linux CPU frequency scaling drivers and governors while also analyzing the power efficiency and thermal impact for Zen 4.


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