Re: [git pull] scheduler fixes

Mike Galbraith
2009-01-17T16:29:06Z

On Sat, 2009-01-17 at 17:12 +0100, Ingo Molnar wrote:
> * Mike Galbraith <efault@gmx.de> wrote:
>
> > Dunno about the IO bits, but..
> >
> > The problem with the C++ testcases seems to be wake_up_all() plunking a
> > genuine thundering herd onto runqueues. The sleeper fairness logic
> > places the entire herd left of min_vruntime, meaning N*sched_latency
> > pain for the poor sods who are setting the runqueue pace.
>
> 100 wakeup pairs that all run and ping-pong between each other?
>
> That creates 200 tasks with an average system load of 100.0, on a
> dual-core system. Is that a fair representation of some real workload, or
> just an unrealistic "gee, look, given enough tasks running I can overload
> the system _this bad_" example?

Looks contrived to me, but it is a hole. Dang sleepers, can't live with
'em can't live without 'em.

-Mike