Re: LWLock contention: I think I understand the problem

>
>
> On Sat, 29 Dec 2001, Bruce Momjian wrote:
>
> > OK, here are the results on BSD/OS 4.2 on a 2-cpu system. The first is
> > before the patch, the second after. Both average 14tps, so the patch
> > has no negative effect on my system. Of course, it has no positive
> > effect either. :-)
>
> Actually it looks slighty worse with the patch. What about CPU usage?

Yes, slightly, but I have better performance on 2 cpu's than 1, so I
didn't expect to see any major change, partially because the context
switching overhead problem doesn't see to exist on this OS.

If we find that it helps single-cpu machines, and perhaps helps machines
that had worse performance on SMP than single-cpu, my guess is it would
be a win, in general.

Let me tell you what I did to test it. I ran /contrib/pgbench. I had
the postmaster configured with 1000 buffers, and ran pgbench with a
scale of 50. I then ran it with 1, 10, 25, and 50 clients using 1000
transactions.

The commands were:

$ createdb pgbench
$ pgbench -i -s 50
$ for CLIENT in 1 10 25 50
do
pgbench -c $CLIENT -t 1000 pgbench
done | tee -a pgbench2_7.2

--
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