Re: pg_test_fsync performance

Robert Haas <robertmhaas@gmail.com> writes:
> Instead of or in addition to a fixed number operations per test, maybe
> we should cut off each test after a certain amount of wall-clock time,
> like 15 seconds.

+1, I was about to suggest the same thing.  Running any of these tests
for a fixed number of iterations will result in drastic degradation of
accuracy as soon as the machine's behavior changes noticeably from what
you were expecting.  Run them for a fixed time period instead.  Or maybe
do a few, then check elapsed time and estimate a number of iterations to
use, if you're worried about the cost of doing gettimeofday after each
write.
        regards, tom lane