Hi Michael, Thanls for your response. Michael Fuhr wrote: > On Mon, Mar 06, 2006 at 04:29:49PM +0100, Joost Kraaijeveld wrote: >> Below are some results of running pgbench, run on a machine that >> is doing nothing else than running PostgreSQL woth pgbench. The >> strange thing is that the results are *constantly alternating* hight >> (750-850 transactions)and low (50-80 transactions), no matter how >> many test I run. If I wait a long time (> 5 minutes) after running >> the test, I always get a hight score, followed by a low one, followed >> by a high one, low one etc. > > The default checkpoint_timeout is 300 seconds (5 minutes). Is it > coincidence that the "long time" between fast results is about the > same? I have not measured the "long wait time". But I can run multiple test in 3 minutes: the fast test lasts 3 sec, the long one 40 secs (see below). During the tests there is not much activity on the partition where the logfiles are (other controller and disk than the database and swap) postgres@panoramix:/usr/lib/postgresql/8.1/bin$ time ./pgbench -c 10 -t 150 test starting vacuum...end. transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 150 number of transactions actually processed: 1500/1500 tps = 531.067258 (including connections establishing) tps = 541.694790 (excluding connections establishing) real 0m2.892s user 0m0.105s sys 0m0.145s postgres@panoramix:/usr/lib/postgresql/8.1/bin$ time ./pgbench -c 10 -t 150 test starting vacuum...end. transaction type: TPC-B (sort of) scaling factor: 100 number of clients: 10 number of transactions per client: 150 number of transactions actually processed: 1500/1500 tps = 37.064000 (including connections establishing) tps = 37.114023 (excluding connections establishing) real 0m40.531s user 0m0.088s sys 0m0.132s >What's your setting? Default. > Are your test results more consistent > if you execute CHECKPOINT between them? Could you tell me how I could do that? Groeten, Joost Kraaijeveld Askesis B.V. Molukkenstraat 14 6524NB Nijmegen tel: 024-3888063 / 06-51855277 fax: 024-3608416 e-mail: J.Kraaijeveld@xxxxxxxxxx web: www.askesis.nl
