Re: BFS vs. mainline scheduler benchmarks and measurements

[Mike Galbraith]

On Wed, 2009-09-09 at 11:02 +0200, Peter Zijlstra wrote:
> On Wed, 2009-09-09 at 10:52 +0200, Mike Galbraith wrote:
> > @@ -1502,7 +1502,8 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
> >          */
> >         if (sched_feat(LAST_BUDDY) && likely(se->on_rq && curr != rq->idle))
> >                 set_last_buddy(se);
> > -       set_next_buddy(pse);
> > +       if (sched_feat(NEXT_BUDDY))
> > +               set_next_buddy(pse);
> >  
> >         /*
> >          * We can come here with TIF_NEED_RESCHED already set from new task
> 
> You might want to test stuff like sysbench again, iirc we went on a
> cache-trashing rampage without buddies.
> 
> Our goal is not to excel at any one load but to not suck at any one
> load.

Oh absolutely.  I wouldn't want buddies disabled by default, I only
added the buddy knob to test effects on fork/exec.

I only posted to patch to give Jens something canned to try out.

	-Mike

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