Re: PostgreSQL pgbench performance regression in 2.6.23+

From: Dhaval Giani
Date: Thu May 22 2008 - 04:28:44 EST

On Thu, May 22, 2008 at 09:10:07AM +0200, Mike Galbraith wrote:
> On Wed, 2008-05-21 at 13:34 -0400, Greg Smith wrote:
> > PostgreSQL ships with a simple database benchmarking tool named pgbench,
> > in what's labeled the contrib section (in many distributions it's a
> > separate package from the main server/client ones). I see there's been
> > some work done already improving how the PostgreSQL server works under the
> > new scheduler (the "Poor PostgreSQL scaling on Linux 2.6.25-rc5" thread).
> > I wanted to provide you a different test case using pgbench that has taken
> > a sharp dive starting with 2.6.23, and the server improvement changes in
> > 2.6.25 actually made this problem worse.
> >
> > I think it will be easy for someone else to replicate my results and I'll
> > go over the exact procedure below.
> Yup, I can reproduce. Running the test with, everything is
> waking/running on one CPU, leaving my box 75% idle. Not good.

Can you try with 2.6.26-rc? There is minimal load balancing for group
scheduling till 25, which might explain the lack of scalability.

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