On Thu, Mar 2, 2017 at 3:51 PM, Pietro Pugni <pietro.pugni@gmail.com> wrote:
> The HBA provided slightly better performance without removing the expander
> and even more slightly faster after removing the expander, but then I tried
> increasing numjob from 1 to 16 (tried also 12, 18, 20, 24 and 32 but found
> 16 to get higher iops) and the benchmarks returned expected results. I guess
> how this relates with Postgres.. probably effective_io_concurrency, as
> suggested by Merlin Moncure, should be the counterpart of numjob in fio?
Kind of. effective_io_concurrency allows the database to send >1
filesystem commands to the hardware from a single process. Sadly,
only certain classes of query can currently leverage this factility --
as you can see, it's a huge optimization.
merlin
