The low end server by chance doesn't have an IDE disk that lies about write completion, or a battery backed disk controller? Try disabling fsync on the new server to get comparable figures. Markus Bertheau 2006/3/21, Edoardo Serra <osdevel@xxxxxxxxxxxxxxx>: > 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 > > > ---------------------------(end of broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings >
