Re: PostgreSQL 9.2 benchmarks

Francois Tigeot <[email protected]> wrote:
> Hi Mindaugas,
> 
> On Mon, Aug 27, 2012 at 04:11:59PM +0100, Mindaugas Rasiukevicius wrote:
> > 
> > I am CC-ing tech-kern as well.
> 
> Good. I was not sure in which of the numerous NetBSD lists I should have
> posted to ;)
> 
> > > On Mon, Aug 27, 2012 at 11:31:30AM +0100, Mindaugas Rasiukevicius
> > > wrote:
> > > > Francois Tigeot <[email protected]> wrote:
> > > 
> > > You're right, it's much better with a Unix socket. NetBSD follows the
> > > FreeBSD curve up to 24 clients (including the peak).
> > > Sadly, it all goes downhill from there.
> > 
> > Good to know.  Do you have a graph somewhere?
> 
> I took some time to run an almost complete serie with NetBSD+AF_UNIX and
> update the pdf document (see page 3).
> Get it there: http://dl.wolfpond.org/benchs/Pg-benchmarks.2012-08.pdf

Thanks.

Interestingly it is not exactly linear, it jumps at the peak.

> > > Performance with 32 clients is on par with the initial 127.0.0.1
> > > results. Tests with 48 or more clients are still running and will
> > > probably yield bad results too.
> > > The system is almost completely unresponsive. Just seeing 'ls' appear
> > > on the remote shell I use takes about 20 seconds with a long pause
> > > between the two letters.
> > 
> > This is somewhat unexpected.  Do you use some unusual configuration or
> > just a plain GENERIC kernel?  Could you perhaps run pgbench under
> > lockstat(8)?
> 
> I'm using an almost-default installation with GENERIC.
> 

If the kernel is before 15th of August, netbsd-6 still had DIAGNOSTIC
option enabled by default, which would affect the performance.  Did you
use a kernel with the option disabled?

Having lockstat output during the benchmark with 24 clients (peak) and
separately with ~32 (when the system gets barely responsive) could help
us to understand the problem better.

-- 
Mindaugas