Re: [RFCv2 PATCH 00/23] sched: Energy cost model for energy-aware scheduling

From: Yuyang Du
Date: Sun Jul 06 2014 - 23:08:27 EST


Hi Morten,

Thanks, got it. Then another question,

On Fri, Jul 04, 2014 at 12:06:13PM +0100, Morten Rasmussen wrote:
> The patch set essentially puts tasks where it is most energy-efficient
> guided by the platform energy model. That should benefit any platform,
> SMP and big.LITTLE. That is at least the goal.
>

I understand energy_diff_* functions are based on the energy model (though I
have not dived into the detail of how you change load balancing based on
energy_diff_*).

Speaking of the engergy model, I am not sure why elaborate "imprecise" energy
numbers do a better job than only a general statement: higher freq, more cap,
and more power.

Even for big.LITTLE systems, big and little CPUs also follow that statement
respectively. Then it is just a matter of where to place tasks between them.
Under such, the energy model might be useful, but still probably cpu_power_orig
(from Vincent) might be enough.

Thanks,
Yuyang
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