Re: Bgwriter behavior

> 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
> 
> The tests were on a machine with a single SCSI drive that doesn't lie
> about fsync.  I found 7.4.X got around 75tps while 8.0 got 100tps, very
> similar to the 65/107 numbers Tom had.

You do realize, that pgbench result comparisons are about as useful as a
fork for eating soup?

On another note, how do you know for sure, that your drive does not lie
about fsync?

Did you run the tests with fsync turned off vs fsync on?

> First, I am confused why we have such a large improvement in 8.0.  Does
> anyone know?  This is a pretty long test so a 33-50% increase is a big
> jump.

bgwriter is responsible I imagine,... I experienced the same improvement
in an early 7.5, just after the bgwriter was added.
(tho my results was about 4-5 times higher in terms of tps rates, hehe)

... John