Linux 5.11 Is Looking Like A Wild And Bumpy Ride On AMD CPUs So Far

[phoronix]

Phoronix: Linux 5.11 Is Looking Like A Wild And Bumpy Ride On AMD CPUs So Far

A few days ago I noted nice AMD EPYC performance improvements with PostgreSQL when running on Linux 5.11 compared to prior kernels. I've confirmed that for even more AMD EPYC servers now that the PostgreSQL uplift is there, but other workloads are unfortunately regressing for both Ryzen and EPYC. Here's the start of an exciting Christmas benchmarking adventure looking at this change with Linux 5.11.....

http://www.phoronix.com/scan.php?page=news_item&px=AMD-EPYC-Linux-5.11-Varies

[baryluk]

How do you know it is "AMD thing"? Test on Intel too.

[Michael]

How do you know it is "AMD thing"? Test on Intel too.

There is a Tiger Lake run in this article and have also ran other tests on Intel hardware with no big surprises.

[Snaipersky]

Really getting tired of how hard schedutil is being pushed in the kernel. It's not as reliably performant as performance, sucks more power than powersave, and feels like a drunken attempt at a more agressive ondemand. Sunk cost fallacy in full force.

[timofonic]

Schedutil needs a lot more research and testing, IMHO. Great concept, but faulty execution.

[indepe]

AFAIK you can verify if the results depend on CPUFreq specifics by setting the CPU "multiplier" in the BIOS manually to a fixed value other than the base value. (Seems to work in my case.)