On Fri, Jan 25, 2013 at 9:38 AM, Francois Tigeot <ftig...@wolfpond.org> wrote: >> On Fri, Jan 25, 2013 at 8:40 AM, Bruce Momjian <br...@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. > > There is. Postgres 9.3+mmap performance on DragonFly is now much better than > these old benchmark results show. > > After the initial disappointing result, I went on a benchmarking/tuning > binge with our Dear Leader Matt Dillon. Taking advantage of some previous > cpu topology work from Mihai Carabas, he heavily improved most performance > shortcomings we found in the DragonFly kernel. > > There were a few mail about this changes on the DragonFly mailing-lists and > Justin Sherill wrote some interesting articles on his blog. > > Some links with more details about improvements and final results: > http://www.shiningsilence.com/dbsdlog/2012/09/19/10403.html > http://www.shiningsilence.com/dbsdlog/2012/10/11/10544.html > http://www.dragonflybsd.org/performance/
Well, that looks pretty cool. Is there anything we can sensibly do to recover the lost performance on FreeBSD and NetBSD? >> 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. > > The original SYSV limits looked like something straight from the 1980s; > we're now autotuning them on DragonFly. Awesome! > FreeBSD and NetBSD still needed manual tuning last time I had a look. Bummer. :-( -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
