Tom Lane <[EMAIL PROTECTED]> wrote: > ITAGAKI Takahiro <[EMAIL PROTECTED]> writes: > > Here is a patch to add duration option (-T) to pgbench instead of > > number of transactions (-t). -t and -T are mutually exclusive. > > This seems like a fairly bad idea, because it introduces a > gettimeofday() call per transaction. On lots of (admittedly mostly > low-end) hardware, that will impose enough overhead to seriously > affect the results.
Are there any evidence about the overhead of gettimeofday here? I think overhead of libpq API and pgbench itself (including generating SQLs) are far bigger than gettimeofday. > set up a timer signal handler that would set > a flag to shut down the test after the appropriate amount of time. There would be some porting problems in a timer singal hander. $ pgbench -n -S -c20 -T10 -M prepared transaction type: SELECT only scaling factor: 1 query mode: prepared number of clients: 20 number of transactions actually processed: 25978 in 10 s tps = 2589.707165 (including connections establishing) tps = 2707.804560 (excluding connections establishing) $ pgbench -n -S -c20 -t1250 -M prepared transaction type: SELECT only scaling factor: 1 query mode: prepared number of clients: 20 number of transactions per client: 1250 number of transactions actually processed: 25000/25000 tps = 2551.834131 (including connections establishing) tps = 2671.118531 (excluding connections establishing) Regards, --- ITAGAKI Takahiro NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
