Re: Perfomance degradation 9.3 (vs 9.2) for FreeBSD

* Andres Freund (andres@2ndquadrant.com) wrote:
> On 2014-04-21 15:47:31 -0400, Stephen Frost wrote:
> > That's certainly unfortunate.  For my 2c, I'd recommend that you write a
> > minimal implementation that allows you to test just the sysv-vs-mmap
> > case (which could certainly take an option, to avoid having to
> > recompile during testing), or even ask if anyone here already has;
>
> I don't think that's something all that easily testable in
> isolation. The behaviour here is heavily related to concurrency.

Concurrency is not terribly hard to generate in a simulated case; I
still feel that doing this independently of PG would probably be better
than involving all the rest of the PG code in testing something this
low-level.

> > I
> > wouldn't be at all surprised if both Robert and Francois did exactly
> > that already, nor would I be surprised if someone volunteered to write
> > such a small C utility for you, if it meant that this issue would be
> > fixed in FreeBSD that much sooner.
>
> I don't know, but the patch for a guc would be < 10 lines. I think I'd
> start with that.

Certainly running a minimally patched PG wouldn't be hard for a kernel
dev either, of course.
Thanks,
    Stephen