Sorry I forgot to add the link. [1] is not the paper Jeff mentioned. [1] Jelena Pjesivac-Grbovic, Graham E. Fagg, Thara Angskun, George Bosilca, Jack J. Dongarra, MPI Collective Algorithm Selection and Quadtree Encoding, 13th European PVM/MPI Users' Group Meeting ( https://www.open-mpi.org/papers/euro-pvmmpi-2006-collective-alg-selection/)
On Tue, Apr 19, 2016 at 9:11 PM, Dorier, Matthieu <mdor...@anl.gov> wrote: > George, > > Thank you for your answer. Is [1] the paper mentioned by Jeff in an > earlier message (ICS 2004)? > Thanks > > Matthieu > ------------------------------ > *From:* users [users-boun...@open-mpi.org] on behalf of George Bosilca [ > bosi...@icl.utk.edu] > *Sent:* Tuesday, April 19, 2016 2:03 PM > *To:* Open MPI Users > *Subject:* Re: [OMPI users] MPI_Bcast implementations in OpenMPI > > Matthieu, > > If you are talking about how Open MPI selects between different broadcast > algorithms you might want to read [1]. We have implemented a dozen > different broadcast algorithms and have run a set of tests to measure their > performance. We then used a quad tree clasiffication algorithm to minimize > the number of switch points, and then generated the C code to dynamically > make the selection based on the message size and the number of > participants. Take a look at the function > ompi_coll_tuned_bcast_intra_dec_fixed in > ompi/mca/coll/tuned/coll_tuned_decision_fixed.c. > > George. > > > > On Tue, Apr 19, 2016 at 4:13 PM, Jeff Squyres (jsquyres) < > jsquy...@cisco.com> wrote: > >> On Apr 15, 2016, at 9:18 AM, Dorier, Matthieu <mdor...@anl.gov> wrote: >> > >> > I'd like to know how OpenMPI implements MPI_Bcast. And if different >> implementations are provided, how one is selected. >> >> This is a fairly complicated topic. This old paper is the foundation for >> how Open MPI works (it's a bit different these days, but the basic concepts >> described in this paper are still mostly relevant): >> >> https://www.open-mpi.org/papers/ics-2004/ >> >> -- >> Jeff Squyres >> jsquy...@cisco.com >> For corporate legal information go to: >> http://www.cisco.com/web/about/doing_business/legal/cri/ >> >> _______________________________________________ >> users mailing list >> us...@open-mpi.org >> Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users >> Link to this post: >> http://www.open-mpi.org/community/lists/users/2016/04/28967.php >> > > > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2016/04/28970.php >
