Re: SYSV shared memory vs mmap performance

On Fri, Jan 25, 2013 at 08:47:51AM -0500, Robert Haas wrote:
> On Fri, Jan 25, 2013 at 8:40 AM, Bruce Momjian <bruce@momjian.us> wrote:
> > Just a reminder we might have *BSD performance issues with our use of
> > Posix shared memory in Postgres 9.3.  I am attaching the PDF the user
> > posted.
> 
> This is a good point.  The question which I believe I asked before and
> haven't gotten an answer to is whether there's some way to get the
> benefit of shm_use_phys with an anonymous mapping.
> 
> It seems to me to be slightly insane to impose draconian shared memory
> limits out of the box and then complain when people switch to some
> other type of shared memory to get around them.  I realize that
> Dragonfly may not be doing that (because I think they may have raised
> the default shared-memory limits), but I believe some of the more
> mainstream BSDs are.
> 
> I suppose we could add a GUC for this, but that's not very appealing, either.

I think we are going to need keep an eye on this during beta.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + It's impossible for everything to be true. +