Re: [PATCH v10 10/15] sched: Introduce a sysctl for Energy Aware Scheduling

From: Ingo Molnar
Date: Tue Dec 11 2018 - 09:15:18 EST

* Quentin Perret <quentin.perret@xxxxxxx> wrote:

> In its current state, Energy Aware Scheduling (EAS) starts automatically
> on asymmetric platforms having an Energy Model (EM). However, there are
> users who want to have an EM (for thermal management for example), but
> don't want EAS with it.

Well, then introduce a new Kconfig variant for EAS, if it's super
important to allow this to be disabled.

Why do we want to disable it - is it not reliable in some circumstances?

> In order to let users disable EAS explicitly, introduce a new sysctl
> called 'sched_energy_aware'. It is enabled by default so that EAS can
> start automatically on platforms where it makes sense. Flipping it to 0
> rebuilds the scheduling domains and disables EAS.

Yeah, making this a sysctl ABI is asking for trouble - this really should
be a Kconfig or debug space knob, at most.