Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm2-V0.7.32-0

[Ingo Molnar]

* Mark_H_Johnson@xxxxxxxxxxxx <Mark_H_Johnson@xxxxxxxxxxxx> wrote:

> > It is easy to hack the scheduler to fix some RT issue but break the 
> > generic scheduler - this solution is not meant to be such a hack.
>
> I agree but I see the big delay of running the RT task to be a symptom
> that the current non RT scheduler is somehow broken. I've reported the
> non RT starvation condition several times. Yes, the second CPU is
> busy, but I really do want to bump cpu_burn (which is non RT & nice)
> to run my (non RT and not nice) stress script / commands instead.

well ... doing global balancing on SMP gets really expensive, really
quick. It's simply not an option for 4 way or higher, and even on 2-way
it's measurable. In the RT case arguably latency is more important than
throughput, but i dont think the same case could be made for nice vs. 
non-nice.

	Ingo
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