Linux 6.5 With AMD P-State EPP Default Brings Performance & Power Efficiency Benefits For Ryzen Servers

[phoronix]

Phoronix: Linux 6.5 With AMD P-State EPP Default Brings Performance & Power Efficiency Benefits For Ryzen Servers

With the new Linux 6.5 kernel stable series one of the many new features is defaulting to the AMD P-State driver with the EPP/active mode compared to the long-used default of the ACPI CPUFreq driver. As shown in various Phoronix articles this can help with the mobile/desktop performance with this new default change while this article is looking at the Ryzen for server benefits too.

https://www.phoronix.com/review/linux65-ryzen-servers

[JEBjames]

Michael

grammar/unclear wording

"As shown in various Phoronix articles this can help with the mobile/desktop performance with this new default change while this article is looking at the Ryzen for server benefits too."

Delete the for. Maybe add commas to fix the grammar, or better yet split into two sentences.

Copy-pasta-here

https://quillbot.com/grammar-check

[cytomax55]

Is there a way to confirm the pstate driver is active?

[okunium]

on the amd 5900x amd_pstate is not default. I really dont understand why. To check if amd_pstate is active run this command - cpupower frequency-info - and check the info that is written in the driver section. if someone has any idea why is amd_pstate not default on 5900x pls share.

[loganj]

cytomax55
cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver
or
cpupower frequency-info

[cytomax55]

loganj
im running 6.5 but its still ACPI
any idea how to force it

[skeevy420]

Maybe add commas to fix the grammar or, better yet, split into two sentences.

Either/or would help a lot.

You also missed some commas between "better yet" and added one on the wrong side of "or"

[Michael]

on the amd 5900x amd_pstate is not default. I really dont understand why. To check if amd_pstate is active run this command - cpupower frequency-info - and check the info that is written in the driver section. if someone has any idea why is amd_pstate not default on 5900x pls share.

It's not due to the 5900X but rather your motherboard.... Check if ACPI CPPC is enabled in BIOS or otherwise check for BIOS updates or something otherwise wonky with your platform.

[okunium]

It's not due to the 5900X but rather your motherboard.... Check if ACPI CPPC is enabled in BIOS or otherwise check for BIOS updates or something otherwise wonky with your platform.

I verified my BIOS settings and all is ok. the ACPI CPPC is enabled and I dont have any wonky behavior/settings. I did see online that many people with 5900/5950x dont have the amd_pstate by default. someone mentioned that it may be a problem with the shared memory. Nevertheless i use the kernel parameter so I'm running amd_pstate=active without a problem. Just a little annoying that its not default and I need to enable it as a kernel parameter. running cpupower frequency-info shows me that the driver is amd-pstate-epp so I know its working for me.

[Ranguvar]

It's not due to the 5900X but rather your motherboard.... Check if ACPI CPPC is enabled in BIOS or otherwise check for BIOS updates or something otherwise wonky with your platform.

It's due to the 5900X.

Unfortunately 'cppc' feature flag does not appear to be exposed for at least desktop non-APU Zen3.
Test `lscpu` and regardless of BIOS setting, it never shows that flag.

Current Linux docs note: "Some new Zen3 processors such as Cezanne provide the MSR registers directly”
I believe this means other Zen3 do not, and for them 'cppc' flag is never exposed.

With my 5950X on 6.5.4, I need both amd_pstate.shared_mem=1 and amd_pstate=active in the kernel command line before the new driver is used.
This is even with default amd_pstate=active (CONFIG_X86_AMD_PSTATE_DEFAULT_MODE=3).

There were notes about shared_mem performance issues in Linux 6.0 docs, but those were removed in subsequent versions.
Any test would be more than welcome ;D