Default TPS performance of 8.3.7

I recently purchased some used hardware for some performance testing of PostgreSQL. I didn't want to interrupt the great work that Mark Wong was doing with the PostgreSQL Performance Lab. The testing I am doing is a bit different than Mark's. Where Mark is testing various filesystem performance via PostgreSQL using DBT2 and FIO and wanted to go up a level. I am testing using the PostgreSQL tool pgbench which is available in contrib. I am also testing in a basically default environment as a way to see how changing different parameters of the postgresql.conf changes overall performance. Hardware Configuration
Newisys Quad Opteron 846 32GB of memory (2) MSA 30s (RAID 10, 14 drives each) (2) HP 6402 Controllers (one for each MSA)
Operating System Configuration
Ubuntu Hardy LTS x86_64 /array1 , ext3, data=writeback elevator=deadline
Outside of the minor operating system changes the system remained in default. The only postgresql.conf parameter I changed was to set checkpoint_segments to 30.
pgbench configuration I used four pgbench instances within a single database with four schemas. Each schema was assigned to its own pgbench user 01-04. The pgbench command used was:
/array1/jd/pgsql/bin/pgbench -U bench01 -s10 -t1000000 -c4 -p 6000 -d bench \
> bench01&
/array1/jd/pgsql/bin/pgbench -U bench02 -s10 -t1000000 -c4 -p 6000 -d bench \
> bench02& 
/array1/jd/pgsql/bin/pgbench -U bench03 -s10 -t1000000 -c4 -p 6000 -d bench \
> bench03&  
/array1/jd/pgsql/bin/pgbench -U bench04 -s10 -t1000000 -c4 -p 6000 -d bench \
> bench04&
Results
pghost:  pgport: 6000 nclients: 4 nxacts: 1000000 dbName: bench
transaction type: TPC-B (sort of)
scaling factor: 100
number of clients: 4
number of transactions per client: 1000000
number of transactions actually processed: 4000000/4000000
tps = 92.279931 (including connections establishing)
tps = 92.279960 (excluding connections establishing)
pghost:  pgport: 6000 nclients: 4 nxacts: 1000000 dbName: bench
transaction type: TPC-B (sort of)
scaling factor: 100
number of clients: 4
number of transactions per client: 1000000
number of transactions actually processed: 4000000/4000000
tps = 91.674708 (including connections establishing)
tps = 91.674739 (excluding connections establishing)
pghost:  pgport: 6000 nclients: 4 nxacts: 1000000 dbName: bench
transaction type: TPC-B (sort of)
scaling factor: 100
number of clients: 4
number of transactions per client: 1000000
number of transactions actually processed: 4000000/4000000
tps = 91.583754 (including connections establishing)
tps = 91.583782 (excluding connections establishing)
pghost:  pgport: 6000 nclients: 4 nxacts: 1000000 dbName: bench
transaction type: TPC-B (sort of)
scaling factor: 100
number of clients: 4
number of transactions per client: 1000000
number of transactions actually processed: 4000000/4000000
tps = 91.616330 (including connections establishing)
tps = 91.616355 (excluding connections establishing)
Each pgbench process executed 4M transactions with an average of ~ 24TPS per client. That is pretty miserable. However remember this is defaults and the defaults will make you checkpoint quite a bit (every 20 seconds or so) with the above stress test. Stay tuned for results as we change specific parameters to see the effect each one has.