Linux's x86_energy_perf_policy Utility Being Extended To AMD CPUs

[phoronix]

Phoronix: Linux's x86_energy_perf_policy Utility Being Extended To AMD CPUs

For AMD Zen 2 and newer systems making use of the modern AMD P-State driver on Linux for CPU frequency scaling, ACPI Collaborative Processor Performance Control (CPPC) interface is being used. For managing the ACPI CPPC energy performance preference (EPP), Intel's x86_energy_perf_policy utility is now being extended to AMD processors...

https://www.phoronix.com/news/AMD-x86_energy_perf_policy

[some_canuck]

Does anyone know how this stuff works on zen1? I noticed my amd systems don't throttle down to a low frequency when idle, and KDE doesn't even show me the option of switching between performance/powersave. Thanks and sorry for the slight OT.

[Girolamo_Cavazzoni]

As far as I know Zen 1 doesn't support CPPC.

[some_canuck]

As far as I know Zen 1 doesn't support CPPC.

Thanks, I was digging around some more and it seems the older acpi-cpufreq only has 3 steps, that might explain some of it, but I very rarely see my 2950x step down from 3.5 to 2.8 or 2.2. I guess it is what it is.

[nranger]

Thanks, I was digging around some more and it seems the older acpi-cpufreq only has 3 steps, that might explain some of it, but I very rarely see my 2950x step down from 3.5 to 2.8 or 2.2. I guess it is what it is.

Have you tried enabling the "conservative" governor with cpufreq? On my Zen+ 3500U part, I could lower the P2 state clock to 1Ghz (from 1.4) and set the governor to conservative and regularly see the chip idle there consistently.

[aceman]

Thanks, I was digging around some more and it seems the older acpi-cpufreq only has 3 steps, that might explain some of it, but I very rarely see my 2950x step down from 3.5 to 2.8 or 2.2. I guess it is what it is.

Is that a 2950X Threadripper? Isn't that Zen+ ? Anyway, I think that does not support CPPC either.
How do you check if it throttles down? I use Zen 1 Threadripper and even when using performance governor, it automatically throttles frequency when idle. Can be seen in /proc/cpuinfo .