Re: kqueue

Robert Haas wrote:
> On Thu, Apr 21, 2016 at 2:22 PM, Andres Freund <andres@anarazel.de> wrote:
> > On 2016-04-21 14:15:53 -0400, Robert Haas wrote:
> >> On Tue, Mar 29, 2016 at 7:53 PM, Thomas Munro
> >> <thomas.munro@enterprisedb.com> wrote:
> >> > On the WaitEventSet thread I posted a small patch to add kqueue
> >> > support[1].  Since then I peeked at how some other software[2]
> >> > interacts with kqueue and discovered that there are platforms
> >> > including NetBSD where kevent.udata is an intptr_t instead of a void
> >> > *.  Here's a version which should compile there.  Would any NetBSD
> >> > user be interested in testing this?  (An alternative would be to make
> >> > configure to test for this with some kind of AC_COMPILE_IFELSE
> >> > incantation but the steamroller cast is simpler.)
> >>
> >> Did you code this up blind or do you have a NetBSD machine yourself?
> >
> > RMT, what do you think, should we try to get this into 9.6? It's
> > feasible that the performance problem 98a64d0bd713c addressed is also
> > present on free/netbsd.
> 
> My personal opinion is that it would be a reasonable thing to do if
> somebody can demonstrate that it actually solves a real problem.
> Absent that, I don't think we should rush it in.

My first question is whether there are platforms that use kqueue on
which the WaitEventSet stuff proves to be a bottleneck.  I vaguely
recall that MacOS X in particular doesn't scale terribly well for other
reasons, and I don't know if anybody runs *BSD in large machines.

On the other hand, there's plenty of hackers running their laptops on
MacOS X these days, so presumably any platform dependent problem would
be discovered quickly enough.  As for NetBSD, it seems mostly a fringe
platform, doesn't it?  We would discover serious dependency problems
quickly enough on the buildfarm ... except that the only netbsd
buildfarm member hasn't reported in over two weeks.

Am I mistaken in any of these points?

(Our coverage of the BSD platforms leaves much to be desired FWIW.)

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services