On Mon, Nov 27, 2017 at 10:40 AM, Scott Marlowe <scott.marl...@gmail.com>
> Generally VMs are never going to be as fast as running on bare metal
> etc. You can adjust it and test it with something simple like pgbench
> with various settings for -c (concurrency) and see where it peaks etc
> with the setting. This will at least get you into the ball park.
None of the built-in workloads for pgbench cares a whit about
effective_io_concurrency. He would have to come up with some custom
transactions to exercise that feature. (Or use the tool people use to run
the TPCH benchmark, rather than using pgbench's built in transactions)
I think the best overall advice would be to configure it the same as you
would if it were not a VM. There may be cases where you diverge from that,
but I think each one would require extensive investigation and
experimentation, so can't be turned into a rule of thumb.