Re: [PATCH 0/4] CPUFreq statistics retrieved by drivers

Lukasz Luba
2020-08-05T19:24:41Z

On 8/4/20 6:27 PM, Florian Fainelli wrote:
>
>
> On 7/29/2020 8:12 AM, Lukasz Luba wrote:
>> Hi all,
>>
>> The existing CPUFreq framework does not tracks the statistics when the
>> 'fast switch' is used or when firmware changes the frequency independently
>> due to e.g. thermal reasons. However, the firmware might track the frequency
>> changes and expose this to the kernel.
>
> Or the firmware might have changed the CPU frequency in response to a
> request from the secure world for instance.

Possible

>
>>
>> This patch set aims to introduce CPUfreq statistics gathered by firmware
>> and retrieved by CPUFreq driver. It would require a new API functions
>> in the CPUFreq, which allows to poke drivers to get these stats.
>
> From a debugging perspective, it would be helpful if the firmware
> maintained statistics were exposed as a super-set of the Linux cpufreq
> statistics and aggregated into them such that you could view the normal
> world vs. secure world residency of a given frequency point. This would
> help because a lot of times, Linux requests freq X, but the secure world
> requires freq Y (with X >= Y) and people do not really understand why
> the resulting power usage is higher for instance.
>
> What are your thoughts on this?
>

I know that Viresh is going to develop patches and improve these
cpufreq stats framework. Maybe he also had this 'aggregation' in mind.
I will leave it him.

Thank you for your feedback.

Regards,
Lukasz