APPLIED [OEM-5.17] Re: [PATCH 0/1][SRU][OEM-5.17/Unstable] Support AMD P-State cpufreq control mechanism

[Timo Aaltonen]

You-Sheng Yang kirjoitti 8.4.2022 klo 5.39:
> BugLink: https://bugs.launchpad.net/bugs/1956509
> 
> [Impact]
> 
> AMD P-State CPU performance scaling driver not yet supported on AMD Zen
> based CPU series.
> 
> [Fix]
> 
> Mainline commits starting at commit d341db8f48ea ("x86/cpufeatures: Add
> AMD Collaborative Processor Performance Control feature flag") from v5.17.
> 
> Even this committed, the defconfig will build it as module, and that
> prevents AMD P-State driver from actually taking effect. Therefore an
> additional fix to the kernel configs is necessary.
> 
> [Test Case]
> 
> $ sudo cpupower frequency-info
> analyzing CPU 0:
>    driver: amd-pstate
>    CPUs which run at the same hardware frequency: 0
>    CPUs which need to have their frequency coordinated by software: 0
>    maximum transition latency: 131 us
>    hardware limits: 400 MHz - 3.10 GHz
>    available cpufreq governors: conservative ondemand userspace powersave
> performance schedutil
>    current policy: frequency should be within 1.60 GHz and 3.10 GHz.
>                    The governor "ondemand" may decide which speed to use
>                    within this range.
>    current CPU frequency: Unable to call hardware
>    current CPU frequency: 1.59 GHz (asserted by call to kernel)
>    boost state support:
>      Supported: yes
>      Active: yes
>      Boost States: 0
>      Total States: 3
>      Pstate-P0: 3100MHz
>      Pstate-P1: 1800MHz
>      Pstate-P2: 1600MHz
> 
> [Where problems could occur]
> 
> The CPPC feature is implemented in two ways depending on underlying HW
> details for the APU/CPU:
> * Dedicated MSR
> * Shared memory
> 
> The metrics used to measure power/performance efficiency don't show any
> improvement on the designs that use shared memory. They do show
> improvements in the MSR designs.
> 
> So the code will only enable it by default on the MSR implementation.
> 
> [Other Info]
> 
> Althought the v5.17 kernel and newer should have already this committed,
> an additional fix to the kernel configs is necessary, and
> unstable/oem-5.17 are also nominated (in a separate thread for they don't
> need other parts but the config).
> 
> You-Sheng Yang (1):
>    UBUNTU: [Config] enable X86_AMD_PSTATE as built-in on amd64
> 
>   debian.master/config/annotations          | 1 +
>   debian.master/config/config.common.ubuntu | 2 +-
>   2 files changed, 2 insertions(+), 1 deletion(-)
> 

applied to oem-5.17, thanks

-- 
t