Re: Can anyone explain this pgbench results? - Mailing list pgsql-performance

From Michael Fuhr
Subject Re: Can anyone explain this pgbench results?
Date
Msg-id 20060306174742.GA13788@winnie.fuhr.org
Whole thread Raw
In response to Can anyone explain this pgbench results?  ("Joost Kraaijeveld" <J.Kraaijeveld@Askesis.nl>)
List pgsql-performance
On Mon, Mar 06, 2006 at 04:29:49PM +0100, Joost Kraaijeveld wrote:
> Below are some results of running pgbench, run on a machine that
> is doing nothing else than running PostgreSQL woth pgbench. The
> strange thing is that the results are *constantly alternating* hight
> (750-850 transactions)and low (50-80 transactions), no matter how
> many test I run. If I wait a long time (> 5 minutes) after running
> the test, I always get a hight score, followed by a low one, followed
> by a high one, low one etc.

The default checkpoint_timeout is 300 seconds (5 minutes).  Is it
coincidence that the "long time" between fast results is about the
same?  What's your setting?  Are your test results more consistent
if you execute CHECKPOINT between them?

--
Michael Fuhr

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