David Hess (davidwhess.delete@this.gmail.com) on September 13, 2021 1:00 pm wrote:
> Daniel B (fejenagy.delete@this.gmail.com) on September 13, 2021 5:20 am wrote:
> >
> > Either the scheduler needs to learn the application behaviour
> > or the application should come tagged, but then the ISV
> > is expected to understand hardware and system energy
> > efficiency, which they don't.
>
> Is there any reason not to expect applications to lie? Of course every
> thread needs to operate on the fastest available core. Ask them.
>
> Alternatively why would developers spend time to distinguish which threads should operate on which cores
> when the result can only make the perceived performance worse? And why risk getting it wrong?
>

I have no answer to this. Even with good intentions, I don't see how it is possible to know which application should run where at any given time without deep performance analysis and an understanding of what the target QoS is. I tried a quick Google search, but not much comes up. Qualcomm says they support affinity settings, but in the end it all depends on the scheduler. Nothing on Apple iOS so far. Some developers asked the question of pinning threads to specific cores but so far the answer seems to be nope. I suspect (most) applications do not set this and it is all magic happening in the scheduler black box.