NetPIPE is a 2 process, pt2pt benchmark. Run it with 2 processes both on one node, and then 2 processes with each on different nodes.
On Jun 1, 2012, at 12:10 PM, Mudassar Majeed wrote: > Dear Jeff, > Can you suggest me a quick guide that can help me testing > specifically the across and within node communication. I have some > submission today so have no time for googling. If the benchmark tells me the > right thing then I will do something accordingly. > > best regards, > Mudassar > > From: Jeff Squyres <jsquy...@cisco.com> > To: Open MPI Users <us...@open-mpi.org> > Cc: Mudassar Majeed <mudassar...@yahoo.com> > Sent: Friday, June 1, 2012 4:52 PM > Subject: Re: [OMPI users] Intra-node communication > > ...and exactly how you measured. You might want to run a well-known > benchmark, like NetPIPE or the OSU pt2pt benchmarks. > > Note that the *first* send between any given peer pair is likely to be slow > because OMPI does a lazy connection scheme (i.e., the connection is made > behind the scenes). Subsequent sends are likely faster. Well-known > benchmarks do a bunch of warmup sends and then start timing after those are > all done. > > Also ensure that you have shared memory support enabled. It is likely to be > enabled by default, but if you're seeing different performance than you > expect, that's something to check. > > > On Jun 1, 2012, at 10:44 AM, Jingcha Joba wrote: > > > This should not happen. Typically, Intra node communication latency are way > > way cheaper than inter node. > > Can you please tell us how u ran your application ? > > Thanks > > > > -- > > Sent from my iPhone > > > > On Jun 1, 2012, at 7:34 AM, Mudassar Majeed <mudassar...@yahoo.com> wrote: > > > >> Dear MPI people, > >> Can someone tell me why MPI_Ssend takes > >> more time when two MPI processes are on same node ...... ?? the same two > >> processes on different nodes take much less time for the same message > >> exchange. I am using a supercomputing center and this happens. I was > >> writing an algorithm to reduce the across node communication. But now I > >> found that across node communication is cheaper than communication within > >> a node (with 8 cores on each node). > >> > >> best regards, > >> > >> Mudassar > >> _______________________________________________ > >> users mailing list > >> us...@open-mpi.org > >> http://www.open-mpi.org/mailman/listinfo.cgi/users > > _______________________________________________ > > users mailing list > > us...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > -- > Jeff Squyres > jsquy...@cisco.com > For corporate legal information go to: > http://www.cisco.com/web/about/doing_business/legal/cri/ > > > -- Jeff Squyres jsquy...@cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
