It's a bit more complicated than that; there are many factors involved: - how many peer MPI processes are involved in the broadcast - how many of those peers are local (and will likely communicate via shared memory, not a network device) and how many are remote - what broadcast algorithm is used (there are many)
So the simplistic logp model won't help you here -- you'll need to be more complicated, and/or dig into the academic papers on these kinds of things. On Apr 4, 2012, at 9:11 AM, anas trad wrote: > Hi Envoyé , > > Thanks for the reply but I want to estimate the time of executing MPI_Bcast > function by mathmatics. I found that we can achieve this by using LogGP model > with this equation: > > T = ceil(log2p) . (L + 2 · o + (n − 1) · G > > but that does not give good accuracy for time evaluation. > > > > --- On Wed, 4/4/12, Aurélien Bouteiller <boute...@eecs.utk.edu> wrote: > > From: Aurélien Bouteiller <boute...@eecs.utk.edu> > Subject: Re: [OMPI users] Need Performance estimation of MPI_Bcast > To: "Open MPI Users" <us...@open-mpi.org> > Cc: "us...@open-mpi.org" <us...@open-mpi.org> > Date: Wednesday, April 4, 2012, 3:50 PM > > You can use the intel mpi benchmark, or skampi. These two programs are > designed to evaluate Moi performance. > > Envoyé de mon iPad > > Le 2012-04-04 à 08:46, anas trad <trada...@yahoo.com> a écrit : > >> Hi all, >> >> I need to know the time estimation of executing MPI_Bcast function on >> Neolith Cluster. Please, can anyone show me how to achieve that. >> >> Thanks, >> Anas >> >> _______________________________________________ >> users mailing list >> us...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/users > > -----Inline Attachment Follows----- > > _______________________________________________ > 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/
