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

[geearf]

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

Same on my 3800X.

[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.

[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.

[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.

[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

[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.

[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.

[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"

[cytomax55]

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

[loganj]

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