AMD Performance On Linux 5.11 Remains Mixed Due To Schedutil With Frequency Invariance
Written by Michael Larabel in Software on 4 January 2021. Page 2 of 3. 33 Comments

Or with a Threadripper 3970X are similar tests regressing as well with Linux 5.11 but by lesser amounts:

While normally the Linux kernel version doesn't make much of a difference for user-space bound workloads like video encoders or file compression, with the frequency invariance support affecting CPU performance state / clocking decisions any workload could potentially be impacted.

But on some systems like this Ryzen 9 3900X box, there wasn't much of a difference at all with Linux 5.11.... Well, aside from the PostgreSQL performance fluctuating on Linux 5.11 and that appears to be due to a separate change in this kernel version.

Similarly, on Zen 1 and older CPUs I have not found many cases of sharp performance differences with Linux 5.11 given the lack of CPPC there and in turn no frequency invariance handling.


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