Re: [RFCv3 PATCH 33/48] sched: Energy-aware wake-up task placement

[Peter Zijlstra]

On Mon, Mar 16, 2015 at 02:47:23PM +0000, Morten Rasmussen wrote:
> > Also, this heuristic for determining sg_target is a big little
> > assumption. I don't think it is necessarily correct to assume that this
> > is true for all platforms. This heuristic should be derived from the
> > energy model for the platform instead.
> 
> I have had the same thought, but I ended up making that assumption since
> I holds for the for the few platforms I have data for and it simplified
> the code a lot. I think we can potentially remove this assumption later.

So the thing is; if we know all the possible behavioural modes of our
system we could pre compute which are applicable to the system at hand.

All we need is a semi formal definition of our model and a friendly
mathematician who can do the bifurcation analysis to find the modal
boundaries and their parameters.

I suspect there is a limited number of modes and parameters and if we
implement all we just need to select the right ones, this could save a
lot of runtime computation.

But yes, we don't need to start with that, we can do the brute force
thing for a while.
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