Postmaster using only 4-5% CPU

Hi all,
         I'm having a very strange performance
problems on a fresh install of postgres 8.1.3
I've just installed it with default option and
--enable-thread-safety without tweaking config files yet.

The import of a small SQL files into the DB (6
tables with 166.500 total records, INSERT syntax)
took me more than 18 minutes as shown below
(output of  "time ./psql benchmarks < dump.sql")

real 18m33.062s
user 0m10.386s
sys 0m7.707s

The server is an
- Intel(R) Xeon(TM) CPU 3.60GHz - 1MB L2
- 1 GB RAM
- 2x HDD SCSI U320 RAID 1 Hardware (HP 6i controller)

The same import, tried on an another low-end
server with a fresh install of postgres 8.1.3 gave me:

real 2m4.497s
user 0m6.234s
sys 0m6.148s

During the test, the postmaster on the first
server (the slow one) uses only a 4% CPU, while
on the second one it reaches 50% cpu usage

I was thinking on a IO bandwidth saturation, but
"vmstat 1" during the import shows me small values for io/bo column

Searching the archive of the ml I found a Disk IO
test I suddenly ran on the slower server as follow

# time bash -c "dd if=/dev/zero of=bigfile bs=8k
count=200000 && sync" (write test)
# time dd if=bigfile of=/dev/null bs=8k (read test)

output of "vmstat 1" during the above test follows:

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
  r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa

Write test
  0 11    540   2344  12152 863456    4    0   340 27848 1709   695  6 53  0 41
  0 11    540   2344  12180 863516    4    0    44 45500 1623   386  0  2  0 98
  0  5    540   3168  12200 862520    0    0   264 44888 1573   315  1  2  0 97

Read test
  0  2    440   2328   6076 849120    0    0 94552     0 1550   624  3 10  0 87
  0  2    440   2248   6104 848936    0    0 94508     0 1567   715  7 10  0 83
  0  3    440   2824   6148 847828    0    0
102540   448 1511   675 14 11  0 75

Values of io/(bi-bo) during the disk test are a
lot higher than during the import operation....

I really have no more clues .... :(

Do you have any ideas ?

Tnx in advance

Regards


Edoardo Serra
WeBRainstorm S.r.l.
IT, Internet services & consulting
Via Pio Foà 83/C
10126 Torino
Tel: +39 011 6966881