Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-6

[K.R. Foley]

Ingo Molnar wrote:
> * K.R. Foley <kr@xxxxxxxxxx> wrote:
>
>
> > OK dumb question. I am going out to get my own personal brown paper
> > bag, since I seem to be wearing it so often. I forgot tasks get
> > removed from the runqueue when they are sleeping, etc. so the active
> > array should empty most of the time. However, with more RT tasks and
> > interactive tasks being thrown back into the active queue I could see
> > this POSSIBLY occasionally starving a few processes???
>
>
> interactive tasks do get thrown back, but they wont ever preempt RT
> tasks. RT tasks themselves can starve any lower-prio process
> indefinitely. Interactive tasks can starve other tasks up to a certain
> limit, which is defined via STARVATION_LIMIT, at which point we empty
> the active array and perform an array switch. (also see
> EXPIRED_STARVING())
>
> 	Ingo
Understood. BTW, I wouldn't consider some possible starvation of lower 
priority, non-realtime tasks to be incorrect behavior for a realtime 
system. The comments in the above email as well as previous emails were 
not intended as complaints or questions of correctness. They were more 
just thoughts generated while thinking about some of the reports of 
non-realtime tasks being starved.

kr
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