Re: [PATCH] Minor scheduler fix to get rid of skipping in xmms

[Nick Piggin]

John Yau wrote:

> > Its actually more important when you have smaller timeslices, because
> > the interactive task is more likely to use all of its timeslice in a
> > burst of activity, then getting stuck behind all the cpu hogs.
>
> Well, I didn't claim it'd be optimal, I just said that it's not worth the
> extra effort.  The interactive task will still finish in O((interactive_time
> / timeslice) * #hogs + interative_time) ms.  As long as the cpu time
> interactive tasks require are very short, they still should finish within a
> reasonable amount of time.

I have found it to be worth the extra effort in my patches, but maybe
you have something different in mind.

> > Yes. Also, say 5 hogs running, an interactive task needs to do something
> > taking 2ms. At a 2ms timeslice, it will take 2ms. At a 1ms timeslice it
> > will take 6ms.
>
> That's assuming that the interactive task gets scheduled first.  In the
> worst case scenario where it gets scheduled last, at 2 ms, it takes 12 ms
> and at 1 ms it also takes 12 ms.  Not much difference there.

No, not much difference. If the worst case scenario happens, it
indicates you have quite a big problem (ie. an interactive task not
allowed to preempt cpu hogs).


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