Re: Bgwriter behavior

From: John Hansen <john(at)geeknet(dot)com(dot)au>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Gavin Sherry <swm(at)linuxworld(dot)com(dot)au>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Bgwriter behavior
Date: 2004-12-28 21:58:06
Message-ID: 1104271086.2196.7.camel@localhost.localdomain
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> > > I ran some tests last week and can report results similar on Tom's test:
> > >
> > > pgbench -i -s 10 bench
> > > pgbench -c 10 -t 10000 bench
> > >

don't you have to specify the scaling factor for the benchmark as well?
as in pgbench -c 10 -t 10000 -s 10 bench ?

> I just tried and got 115tps with fsync off vs 100 with fsync on, so
> fsync is certainly doing something.

well, I usually get results that differ by that much from run to run.
Probably you ran in to more checkpoints on the second test.

Also, did you reinitialize the bench database with pgbench -i ?

... John

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