Re: [SHED] Questions.

[Robert Love]

On Sun, 2003-08-31 at 15:31, Ian Kumlien wrote:

> Since they would have a high pri still, and preempt is there... it
> should be back on the cpu pretty quick.

Ah, but no!  You assume we do not have an expired list and round robin
scheduling.

Once a task exhausts its timeslice, it cannot run until all other tasks
exhaust their timeslice.  If this were not the case, high priority tasks
could monopolize the system.

> But, it also creates problems for when a interactive process becomes a
> cpu hog. Like this the detection should be faster, but should be slowed
> down somewhat.

I agree, although I do think it responds fairly quick.  But, regardless,
this is why I am interested in Nick's work.  The interactivity estimator
can never be perfect.

> But, hogs would instead cause a context switch hell and lessen the
> throughput on server loads...

Hm, why?

> I don't see how priorities would be questioned... Since, all i say is
> that a task that gets preempted should have a guaranteed time on the cpu
> so that we don't waste cycles doing context switches all the time. 

But latency is important.

	Robert Love


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