Re: SYSV shared memory vs mmap performance

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.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company