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 >
