Hi Thomas,
On 01/10/2018 01:09, Thomas Munro wrote:
> I don't know why the existence of the kqueue should make recvfrom()
> slower on the pgbench side. That's probably something to look into
> off-line with some FreeBSD guru help. Degraded performance for
> clients on the same machine does seem to be a show stopper for this
> patch for now. Thanks for testing!
Glad to be helpful!
I've tried running pgbench from a separate VM and in fact kqueue
consistently takes the lead with 5-10% more tps on select/prepared
pgbench on NetBSD too.
What I have observed is that sys cpu usage is ~65% (35% idle) with
kqueue, while unpatched master averages at 55% (45% idle): relatively
speaking that's almost 25% less idle cpu available for a local pgbench
to do its own stuff.
Running pgbench locally shows an average 47% usr / 53% sys cpu
distribution w/ kqueue vs more like 50-50 w/ vanilla, so I'm inclined to
think that's the reason why we see a performance drop instead. Thoguhts?
Cheers
--
Matteo Beccati
Development & Consulting - http://www.beccati.com/