New: [amd-pstate 6.15] Frequency Scaling Will Not Scale Above Lowest Non-Linear Performance on Ryzen 7 5700U

https://bugzilla.kernel.org/show_bug.cgi?id=219851

Bug ID: 219851
Summary: [amd-pstate 6.15] Frequency Scaling Will Not Scale
Above Lowest Non-Linear Performance on Ryzen 7 5700U
Product: Power Management
Version: 2.5
Hardware: AMD
OS: Linux
Status: NEW
Severity: normal
Priority: P3
Component: cpufreq
Assignee: [email protected]
Reporter: [email protected]
Regression: No

Created attachment 307781
--> https://bugzilla.kernel.org/attachment.cgi?id=307781&action=edit
amd-pstate-triage log from bad kernel

On a kernel build with 6.15 amd-pstate material taken from
https://web.git.kernel.org/pub/scm/linux/kernel/git/superm1/linux.git/tag/?h=amd-pstate-v6.15-2025-03-03,
a user noticed that frequency scaling will not scale above Lowest Non-Linear Perf. Git bisect shows the below as the first bad commit.

620136ced35a9329f4d1ea90e51bee2dfd7ee5b0 is the first bad commit commit 620136ced35a9329f4d1ea90e51bee2dfd7ee5b0

Author: Dhananjay Ugwekar <[email protected]>
Date:   Wed Feb 5 11:25:18 2025 +0000

cpufreq/amd-pstate: Modularize perf<->freq conversion

Delegate the perf<->frequency conversion to helper functions to reduce code duplication, and improve readability.

Link:
https://lore.kernel.org/r/[email protected]

 drivers/cpufreq/amd-pstate.c | 57
++++++++++++++++++++++++++++++---------------------------
 1 file changed, 30 insertions(+), 27 deletions(-)

Attached are amd-pstate-triage logs from good and bad kernels. They are not necessarily equal because a revert of the bad commit isn't trivial with the whole 6.15 content so the "good" kernel only has patches from Dhananjay's series and the bad commit reverted.

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--- Comment #1 from Eric Naim ([email protected]) --- Created attachment 307782
--> https://bugzilla.kernel.org/attachment.cgi?id=307782&action=edit
amd-pstate-triage log from good kernel

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https://bugzilla.kernel.org/show_bug.cgi?id=219851

--- Comment #2 from Dhananjay Ugwekar (AMD) ([email protected]) --- Hello Eric,

1. Could you please give more details on how to reproduce the issue? which governor, amd-pstate mode (when the issue was observed), workload. Are you able to reproduce the issue on your machine as well?
2. Just to confirm, does the user have
https://web.git.kernel.org/pub/scm/linux/kernel/git/superm1/linux.git/commit/?h=amd-pstate-v6.15-2025-03-03&id=f6c0b760290951688697d9debbb2b8462c423a48,
in his tree, it fixed a corner case in the culprit commit that you pointed to.

Thanks,
Dhananjay

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--- Comment #3 from Eric Naim ([email protected]) --- (In reply to Dhananjay Ugwekar (AMD) from comment #2)

Hi Dhananjay,

Unfortunately the user that first reported this issue hasn't reached out to me since, so for now I'll give you information regarding what I already know.

No STR was given, from the lack of info I believe it's just a general case, e.g. if you run stress-ng -c $(nproc), you *should* see the issue (entirely speculation). This regression only happens with the active driver. Both passive and guided mode was reported to behave correctly.

I can't reproduce this either because my laptop is a Zen3 laptop. It is likely that it is limited to Zen2.

Yes, you can see the related tree
https://github.com/CachyOS/linux/tree/6.14/amd-pstate. It's not 1:1 with Mario's tree but I diffed both trees and the only difference was commit 34562659110a42276d63f8b5a9d522d2400b2df2 which is from the "Dynamic ITMT core ranking support" series.

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--- Comment #4 from Eric Naim ([email protected]) --- (In reply to Dhananjay Ugwekar (AMD) from comment #2) Hi Dhananjay,

It looks like the user didn't have that commit after all. They were using an older revision of the patchset that didn't have the updated amd-pstate commits. I should've asked them to crosscheck their issue with the kernel in our repositories first. Sorry to have wasted your time. I'm going to close this as invalid.

Regards,
Eric

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Eric Naim ([email protected]) changed:

What |Removed |Added
----------------------------------------------------------------------------

             Status|NEW                         |RESOLVED
         Resolution|---                         |INVALID

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--- Comment #5 from Dhananjay Ugwekar (AMD) ([email protected]) --- No worries, happy to help.

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