Re: [RFC] sched: CPU topology try

[Peter Zijlstra]

On Wed, Jan 08, 2014 at 12:35:34PM +0000, Morten Rasmussen wrote:
> > The harder case is where all 3 tasks are of equal weight; in which case
> > fairness would mandate we (slowly) rotate the tasks such that they all
> > get 2/3 time -- we also horribly fail at this :-)
> 
> I have encountered that one a number of times. All the middleware noise
> in Android sometimes give that effect.

You've got a typo there: s/middleware/muddleware/ :-)

> I'm not sure if the NUMA guy would like rotating scheduler though :-)

Hurmph ;-) But yes, the N+1 tasks on a N cpu system is rotten; any
static solution gets 2 tasks that run at 50%, any dynamic solution gets
the migration overhead issue.

So while the dynamic solution would indeed allow each task to (on
average) receive N/N+1 time -- a vast improvement over the 50% thing, it
doesn't come without down sides.
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