Alexander Staubo <alex@xxxxxxxxxxxxxxx> writes: > No, fsync=on. The tps values are similarly unstable with fsync=off, > though -- I'm seeing bursts of high tps values followed by low-tps > valleys, a kind of staccato flow indicative of a write caching being > filled up and flushed. It's notoriously hard to get repeatable numbers out of pgbench :-( A couple of tips: * don't put any faith in short runs. I usually use -t 1000 plus -c whatever. * make sure you loaded the database (pgbench -i) with a scale factor (-s) at least equal to the maximum -c you want to test. Otherwise you're mostly measuring update contention. * pay attention to when checkpoints occur. You probably need to increase checkpoint_segments if you want pgbench not to be checkpoint-bound. regards, tom lane
