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 50do    pgbench -c $CLIENT -t 1000 pgbenchdone | tee -a
pgbench2_7.2

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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