Re: LWLock contention: I think I understand the problem

Hannu Krosing <hannu@tm.ee> writes:
> Could you rerun some of the tests on the same hardware but with 
> uniprocesor kernel

I don't have root on that machine, but will see what I can arrange next
week.

> There were some reports about very poor insert performance on 4way vs 1way
> processors.

IIRC, that was fixed for 7.2.  (As far as I can tell from profiling,
contention for the shared free-space-map is a complete nonissue, at
least in this test.  That was something I was a tad worried about
when I wrote the FSM code, but the tactic of locally caching a current
insertion page seems to have sidestepped the problem nicely.)

>> psql -c 'vacuum' $DB
>> 
> Should this not be 'vacuum full' ?

Don't see why I should expend the extra time to do a vacuum full.
The point here is just to ensure a comparable starting state for all
the runs.
        regards, tom lane