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

[Peter Zijlstra]

On Thu, Mar 26, 2015 at 10:21:24AM +0000, Juri Lelli wrote:
>  - what about other sched classes? I know that this is very premature,
>    but I can help but thinking that we'll need to do some sort of
>    aggregation of requests, and if we put triggers in very specialized
>    points we might lose some of the sched classes separation

So for deadline we can do P state selection (as you're well aware) based
on the requested utilization. Not sure what to do for fifo/rr though,
they lack much useful information (as always).

Now if we also look ahead to things like the ACPI CPPC stuff we'll see
that CFS and DL place different requirements on the hints. Where CFS
would like to hint a max perf (the hardware going slower due to the code
consisting of mostly stalls is always fine from a best effort energy
pov), the DL stuff would like to hint a min perf, seeing how it 'needs'
to provide a QoS.

So we either need to carry this information along in a 'generic' way
between the various classes or put the hinting in every class.

But yes, food for thought for sure.
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