Re: Automatically sizing the IO worker pool - Mailing list pgsql-hackers

On Wed, Jul 30, 2025 at 10:15 PM Dmitry Dolgov <9erthalion6@gmail.com> wrote:
> As a side note, I was trying to experiment with this patch using
> dm-mapper's delay feature to introduce an arbitrary large io latency and
> see how the io queue is growing.

FWIW, here's what I came up with while experimenting with that sort of thing:

      shared_preload_libraries=io_limit
      io_limit.ios_per_second=6000

That differs from eg dm-mapper delays by making everything seem like
slow direct I/O, which seemed more interesting for this project.  For
example if you run some continuous workload while you SET
io_limit.ios_per_second to various numbers, with
io_workers_idle_timeout set fairly low, you can monitor the pool
adjustments.