Re: [RFC] scheduler: improve SMP fairness in CFS

[Chris Snook]

Chris Friesen wrote:
> Ingo Molnar wrote:
>
> > the 3s is the problem: change that to 60s! We no way want to 
> > over-migrate for SMP fairness, the change i did gives us reasonable 
> > long-term SMP fairness without the need for high-rate rebalancing.
>
> Actually, I do have requirements from our engineering guys for 
> short-term fairness.  They'd actually like decent fairness over even 
> shorter intervals...1 second would be nice, 2 is acceptable.
>
> They are willing to trade off random peak performance for predictability.
>
> Chris

The sysctls for CFS have nanosecond resolution.  They default to 
millisecond-order values, but you can set them much lower.  See sched_fair.c for 
the knobs and their explanations.

	-- Chris
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