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

Florian Fainelli
2020-08-04T17:27:19Z

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.

>
> 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?
--
Florian