Re: kqueue

On Thu, Sep 15, 2016 at 10:48 AM, Keith Fiske <keith(at)omniti(dot)com> wrote:
> Thomas Munro brought up in #postgresql on freenode needing someone to test a
> patch on a larger FreeBSD server. I've got a pretty decent machine (3.1Ghz
> Quad Core Xeon E3-1220V3, 16GB ECC RAM, ZFS mirror on WD Red HDD) so offered
> to give it a try.
>
> Bench setup was:
> pgbench -i -s 100 -d postgres
>
> I ran this against 96rc1 instead of HEAD like most of the others in this
> thread seem to have done. Not sure if that makes a difference and can re-run
> if needed.
> With higher concurrency, this seems to cause decreased performance. You can
> tell which of the runs is the kqueue patch by looking at the path to
> pgbench.

Thanks Keith. So to summarise, you saw no change with 1 client, but
with 4 clients you saw a significant drop in performance (~93K TPS ->
~80K TPS), and a smaller drop for 64 clients (~72 TPS -> ~68K TPS).
These results seem to be a nail in the coffin for this patch for now.

Thanks to everyone who tested. I might be back in a later commitfest
if I can figure out why and how to fix it.

--
Thomas Munro
http://www.enterprisedb.com