Postgresql performance on Opteron 8 CPU

Hi,

We've been using a 4 CPU Opteron (16GB) for the past several months, and
have now upgraded to an 8 CPU machine with 32GB. Basically, we've taken
the postgresql.conf from the 4 way, and used that in the 8 way without
making any changes. Shared memory for postgresql in both machines is
256MB which seemed to give us the best performance on the 4 way. RHEL
4.0 is the OS, and we use the latest SRPMS to install Postgresql.

Running PGBench on the 8 way gives us about 60% of the performance of
the 4 way machine. We're running Postgresql 8.03 on both machines. We
later installed Postgresql 7.4.6 on the 8 way, and that gave us
performance that was comparable (but not in excess) of the 4 way machine.

We're using a fast I/O subsystem (external storage array) for both
machines, so things are equivalent on that front. I remember seeing a
report on Postgresql issues with 8 CPU machines recently.

Does anyone have suggestions that could improve performance?

--
Warmest regards,

Ericson Smith
Programmer
Did-it Search Marketing
Raise Your Expectations...
---
http://www.did-it.com
55 Maple Avenue, 3rd Floor
Rockville Center, NY 11570

P: 800.932.7761 Ext 237
E: eric@did-it.com

Jupiter Research rates Did-it the #1 Search Engine Marketing agency for market suitability in Search Engine Marketing
AgencyConstellation Report