Re: [PATCH 0/4] pending scheduler updates

[Mike Galbraith]

On Wed, 2008-10-22 at 14:42 +0200, Ingo Molnar wrote:
> * Mike Galbraith <efault@xxxxxx> wrote:
> 
> > > > With that patch, pgsql+oltp scales perfectly.
> > > 
> > > hm, tempting.
> > 
> > I disagree.  Postgres's scaling problem is trivially corrected by 
> > twiddling knobs (or whatnot). [...]
> 
> okay, then we need to document it a bit more: what knobs need twiddling 
> to make it scale perfectly?

Twiddle sched_wakeup_granularity_ns or just turn FAIR_SLEEPERS off for
best pgsql+oltp scalability.ï  Pgsql+oltp collapse is delicate.  It
doesn't take much to send it one way or the other.  Cut preempt a wee
bit, and it can snap right into shape.

I think we need to penalize sleepers a wee bit as load climbs in general
though, everybody begins to like preemption less as load increases.
Mysql+oltp improves as well, and it loves preempt at modest load.

	-Mike

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/