On Tue, 2010-05-04 at 21:34 +0200, Stefan Kaltenbrunner wrote:
> FWIW - I'm seeing a behaviour here under pgbench -S workloads that looks
> kinda related.
>
> using -j 16 -c 16 -T 120 I get either 100000tps and around 660000
> contextswitches per second or on some runs I end up with 150000tps and
> around 1M contextswitches/s sustained. I mostly get the 100k result but
> once in a while I get the 150k one. And one even can anticipate the
> final transaction rate from watching "vmstat 1"...
>
> I'm not sure yet on what is causing that behaviour but that is with
> 9.0B1 on a Dual Quadcore Nehalem box with 16 cpu threads (8+HT) on a
> pure in-memory workload (scale = 20 with 48GB RAM).
Educated guess at a fix: please test this patch. It's good for
performance testing, but doesn't work correctly at failover, which would
obviously be addressed prior to any commit.
--
Simon Riggs www.2ndQuadrant.com