Re: [ckrm-tech] Re: [PATCH 0/9] CPU controller

[Mike Galbraith]

On Fri, 2006-04-28 at 20:26 +1000, Con Kolivas wrote:
> On Friday 28 April 2006 20:16, Mike Galbraith wrote:
> > > How many tasks? Your function was O(n) so the more tasks the longer that
> > > max value was.
> >
> > Nope.  It's not O(tasks), it's O(occupied_queues).  Occupied queues is
> > generally not a large number.
> 
> Ok well that P4 does about 700,000 context switches per second so 4us sounds 
> large to me.

I'm not always calling it now, only when necessary.  In any case, I'd
much rather pay 4us (it averages 1) every 100ms when at 100% cpu than
take a multi-second latency hit for high priority tasks as now occurs
with a heavy load when the array switch is forced.  This hit is more
likely with my (unfortunately necessary) change to wake tasks on the
expired array.  That's why I started trying to eliminate the switch.

	-Mike

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