Messages in this thread | | | Subject | Re: [PATCH 0/4] pending scheduler updates | From | Mike Galbraith <> | Date | Wed, 22 Oct 2008 12:32:08 +0200 |
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On Wed, 2008-10-22 at 12:03 +0200, Mike Galbraith wrote:
> It has positive effects too, but IMHO, the bad outweigh the good.
BTW, most dramatic on the other end of the spectrum is pgsql+oltp. With preemption as is, it collapses as load climbs to heavy with preemption knobs at stock. Postgres uses user-land spinlocks and _appears_ to wake others while these are still held. For this load, there is such a thing as too much short-term fairness, preempting lock holder creates nasty gaggle of contended lock spinners. It's curable with knobs, and I think it's postgres's own fault, but may be wrong.
With that patch, pgsql+oltp scales perfectly.
-Mike
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