Updated AMD P-State Driver Posted For Improving Linux Power Efficiency

[phoronix]

Phoronix: Updated AMD P-State Driver Posted For Improving Linux Power Efficiency

A fourth iteration of the AMD P-State CPU frequency scaling driver patches for Linux have been sent out for review and testing...

https://www.phoronix.com/scan.php?page=news_item&px=AMD-P-State-v4

[bezirg]

Great. Is this patch still zen3-only or is the zen2 support turned on already?

[mlau]

Great. Is this patch still zen3-only or is the zen2 support turned on already?

there's nothing inherently zen3 specific about it. bios must provide "sane" cppc tables, and either have a cpu which has the amd cppc capability bit set (4000G for example) or the pcc mechanism.
It works for me on 4750g out of the box; on the 5950x it needs to be force enabled with "amd_pstate.shared_mem=1"

[Mez']

there's nothing inherently zen3 specific about it. bios must provide "sane" cppc tables, and either have a cpu which has the amd cppc capability bit set (4000G for example) or the pcc mechanism.
It works for me on 4750g out of the box; on the 5950x it needs to be force enabled with "amd_pstate.shared_mem=1"

I have the 4700u, is there a way to check if this is activated?
And if not, is it just a kernel parameter to pass?
Or do I also need to tell my system somehow to drop cpufreq governors and use this instead?

[mlau]

if you have "amd_cppc" in /proc/cpuinfo after applying this patchset, the driver should work out of the box on 4700u (which is also renoir, so my guess is yes).
Also file "/sys/devices/system/cpu/cpufreq/policy0/scaling_driver" should contain "amd-pstate" if your bios is also fine.
On an idle system you should see a lot of cores at around 500MHz instead of 2000MHz as is with acpi-cpufreq.

[microcode]

Very cool. Valve found the way to work around AMD's inability to manage software teams: hold their hand through everything. :+ )

[aufkrawall]

amdgpu + dc is still ~entirely maintained by AMD only, and I think very successfully (though Valve surely will provide feedback or perhaps even MRs for the Steam Deck). CPU clock governors is a different domain, situation is just sucky on Linux in general and I can imagine that collaboration with AMD could be better than it would be with Intel. Some company needs to tell Intel that intel_pstate=powersave is atrocious garbage...

[PuckPoltergeist]

Build as module, I get

ERROR: could not insert 'amd_pstate': No such device

when trying to load it.

[mlau]

Build as module, I get

ERROR: could not insert 'amd_pstate': No such device

when trying to load it.

either your bios has buggy cppc tables, or you need to modprobe it as "modrobe amd-pstate shared_mem=1"

[reba]

if you have "amd_cppc" in /proc/cpuinfo after applying this patchset, the driver should work out of the box on 4700u (which is also renoir, so my guess is yes).
Also file "/sys/devices/system/cpu/cpufreq/policy0/scaling_driver" should contain "amd-pstate" if your bios is also fine.
On an idle system you should see a lot of cores at around 500MHz instead of 2000MHz as is with acpi-cpufreq.

True:


Setting amd_pstate.shared_mem=1 wasn't necessary here, but that could be because of xanmod's kernel.