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

[aviallon]

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

I'm not sure it is due to the CPU. Michael is probably right.
My 5950X is able to use amd_pstate without any options on the cmdline.
And I'm using Linux 6.5.4 too.

[Anux]

Test `lscpu` and regardless of BIOS setting, it never shows that flag.

Look for BIOS updates for your board, the CPU is not the reason.

[ptr1337]

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

You don't need shared_mem. I have also a 5900X and you only require amd-pstate=active.

[geearf]

You don't need shared_mem. I have also a 5900X and you only require amd-pstate=active.

Same on my 3800X.

[ATLief]

I’d love to see some comparisons for amd_pstate=passive, especially with the performance governor. That’s what I currently use, but I’d gladly use something else if it yields more performance.

Has anyone compared them?

[Ranguvar]

I'm not sure it is due to the CPU. Michael is probably right.
My 5950X is able to use amd_pstate without any options on the cmdline.
And I'm using Linux 6.5.4 too.

Look for BIOS updates for your board, the CPU is not the reason.

Same on my 3800X.

Thank you all for your reports!
Could still be UEFI bug.

Could any of you please check `lscpu` for cppc feature flag?
I find it hard to believe even Zen2 has exposed MSRs for CPPC, more likely it's defaulting to shared memory mode..?

[geearf]

Thank you all for your reports!
Could still be UEFI bug.

Could any of you please check `lscpu` for cppc feature flag?
I find it hard to believe even Zen2 has exposed MSRs for CPPC, more likely it's defaulting to shared memory mode..?

Yeah I don't see the flag on my Zen2, that would explain why amd-pstate is not default.

[finalzone]

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.

Quick question, have you updated your motherboard BIOS?
I have a the exact Ryzen 5900X running on ASUS PRIME X570 motherboard supporting amd_pstate=active by default on kernel 6.5.4.

[Ranguvar]

Quick question, have you updated your motherboard BIOS?
I have a the exact Ryzen 5900X running on ASUS PRIME X570 motherboard supporting amd_pstate=active by default on kernel 6.5.4.

I am using F36 BIOS on a Gigabyte X570 Aorus Master, from Dec 28th 2022, with AGESA V2 1.2.0.7.

I tried resetting BIOS completely and changing many other settings but could not get cppc feature flag to show or find anyone else with desktop Zen3 and working cppc flag.

Last time I updated BIOS it was fraught with issues as I have a complex display and boot setup, so I am waiting until something newer releases other than F37f (AGESA V2 1.2.0.A).
No related change notes. If nothing newer releases I will try again in a few weeks.

[finalzone]

I am using F36 BIOS on a Gigabyte X570 Aorus Master, from Dec 28th 2022, with AGESA V2 1.2.0.7.

I tried resetting BIOS completely and changing many other settings but could not get cppc feature flag to show or find anyone else with desktop Zen3 and working cppc flag.

Last time I updated BIOS it was fraught with issues as I have a complex display and boot setup, so I am waiting until something newer releases other than F37f (AGESA V2 1.2.0.A).
No related change notes. If nothing newer releases I will try again in a few weeks.

I just updated the BIOS and ASUS Prime X570 and got hit with a bug. The settings were left on AUTO by default which suggest vendors issue. Workaround is to add parameters.