[Buildroot] [External] - Re: [PATCH 1/1] configs/raspberrypi*: stop setting powersave as the default CPU governor

[Carlos Alberto Lopez Perez]

On 24/10/2023 17:17, Vincent Fazio wrote:
>> That is not true. Upstream RPi-OS defaults to the ondemand governor. The
>> kernel boots with powersave but there is an init scripy that swichts it to
>> ondemand as soon as the board boots unless the user press the shift key.
>>
> 
> Sorry, I wasn't very clear here. When I said upstream, I meant "upstream RPi kernel", which default to powersave. RPi-OS does have a mechanism to switch governors post boot.
> 
> FWIW, we use vanilla arm64 Debian Bookworm on our RPis and had to tackle this problem too, so I do understand where you're coming from.
> 
> Again, I think the biggest issue is just informing users and letting them choose the right solution for their deployment.
> 

I'm all in for informing users and letting them to choose a default.

On the other hand a default selection has to be made for those users
that don't care or don't have time to read the documentation.

And I repeat: RPi-OS defaults to ondemand governor because they change
the governor on boot with an init script.

The governor powersave is only used for the first seconds of the boot
process and is opt-in the rest of the time (the user has to press shit
key meanwhile booting to keep it).

So the current status quo is this one:

 1) RPi default CPU governor of mainline Linux kernel: schedutil or
ondemand (depends on the kernel version)
 2) RPi default CPU governor of RPi-OS: ondemand (powersave opt-in if
user press shit)
 3) RPi default CPU governor of buildroot: powersave


Why buildroot would want to have a default of powersave that not even
matches what RPi-OS does?