Re: Configure template change to use SysV Semaphors on darwin

Chris Marcellino <cmarcellino(at)apple(dot)com> writes:
> On Feb 7, 2007, at 4:54 PM, Tom Lane wrote:
>> Outta curiosity, can you measure any performance difference?

> Using pgbench, on 1 million records at each of 1, 10 and 100
> concurrent users, I get the same results before and after the patch.
> I'm not sure if pgbench is the most appropriate benchmark for this
> though.

Probably not. The issues about Darwin's POSIX-sema implementation
are (a) eating backend open-file slots, which won't matter when a
backend only touches a few different tables as pgbench does; and
(b) extra process-launch overhead, which won't matter to pgbench
because it's not launching new backends throughout the test.

I'm not sure that there is any standardized test that measures
these things, and yet it seems like it oughta matter in the real
world ...

regards, tom lane