Re: [PATCH RESEND 1/3] perf/x86/intel/cstate: Add Clearwater Forest support

From: Ingo Molnar

Date: Thu Oct 30 2025 - 05:09:19 EST



* Zide Chen <zide.chen@xxxxxxxxx> wrote:

> Clearwater Forest is based on the Darkmont Atom microarchitecture.
> From the perspective of C-state residency profiling, it supports the
> same residency counters as Sierra Forest: CC1/CC6, PC2/PC6, and MC6.
>
> Please note that the C1E residency counter can only be read via PMT,
> not MSR. Therefore, tools relying on the perf_event framework cannot
> access the C1E residency.
>
> Cc: Artem Bityutskiy <artem.bityutskiy@xxxxxxxxx>
> Reviewed-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
> Signed-off-by: Zhenyu Wang <zhenyuw.linux@xxxxxxxxx>
> Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>

So, this is not a valid SOB chain: primary author should be the first
SOB, or if it was co-developed, it should have the proper
Co-developed-by tags.

Here I can see two possibilities:

(1) if Zhenyu Wang was the primary author, and Zide Chen reviewed,
tested and submitted it upstream, then:


| From: Zide Chen <zide.chen@xxxxxxxxx>
| Subject: [PATCH 1/3] perf/x86/intel/cstate: Add Clearwater Forest support

From: Zhenyu Wang <zhenyuw.linux@xxxxxxxxx>
...

Signed-off-by: Zhenyu Wang <zhenyuw.linux@xxxxxxxxx>
Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>

(I.e. add the extra From line as the first line of the changelog.)

(2) if it was co-developed, with Zhenyu Wang and Zide Chen having each
written unique lines of code of their own that finally resulted in
this submission, then:

| From: Zide Chen <zide.chen@xxxxxxxxx>
| Subject: [PATCH 1/3] perf/x86/intel/cstate: Add Clearwater Forest support

...

Co-developed-by: Zide Chen <zide.chen@xxxxxxxxx>
Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>
Co-developed-by: Zhenyu Wang <zhenyuw.linux@xxxxxxxxx>
Signed-off-by: Zhenyu Wang <zhenyuw.linux@xxxxxxxxx>

Which one was it? :-)

Thanks,

Ingo