Re: [RFC patch 1/2] sched: dynamically adapt granularity with nr_running

Peter Zijlstra
2010-09-13T09:37:56Z

On Mon, 2010-09-13 at 11:16 +0200, Mike Galbraith wrote:
> On Mon, 2010-09-13 at 10:35 +0200, Peter Zijlstra wrote:
> > On Mon, 2010-09-13 at 09:08 +0200, Mike Galbraith wrote:
> > > We need a better fork fairness gizmo.
> >
> > Proper zero-lag insertion would do. Much sadness in that tracking that
> > costs a u64 mult per enqueu/dequeue and using it adds a s64 div.
>
> (math _sucks_:)
>
> > But if you want, have a play with:
>
> maximum latency: 48475.3 µs
> average latency: 6881.4 µs
> missed timer events: 0
>
> Darn.
>
> make -j3 is gaining a tad over a hog as well, roughly the same as
> turning START_DEBIT off.

Hrmm,. could it be fair_sleeper muck placing too many tasks too far left
on wakeup starving others?