Messages in this thread | | | Subject | Re: [PATCH 0/4] pending scheduler updates | From | Mike Galbraith <> | Date | Wed, 22 Oct 2008 15:05:12 +0200 |
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On Wed, 2008-10-22 at 14:42 +0200, Ingo Molnar wrote: > * Mike Galbraith <efault@gmx.de> 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. 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
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