Thanks Jeff, I know it depends and I want to know exactly what is the dependency and general complexity analysis.
Is it really no documentation at all ? For example you said "to be replaced soon", then what is the algorithms that will be used to replace ? Is there any publication available ? In another words, how do you know they will be replaced by which algorithm, please teach me ! Cheers, Vu On Wed, Aug 24, 2011 at 9:07 PM, Jeff Squyres <jsquy...@cisco.com> wrote: > On Aug 23, 2011, at 3:32 AM, Hoang-Vu Dang wrote: > > > Where could I find a detailed documentation about algorithms that has > been using in Open MPI ? > > Unfortunately, you probably won't. > > > For example, I would like to answer following questions: how MPI_Algather > operation is done? what is the complexity in term of the number of data > send/receive given a number of node involved? what is the data structure > behind ?. Same as for MPI_Alreduce etc.. > > All of OMPI's collectives are implemented as plugins under the > ompi/mca/coll/ tree. There are several different plugins in that tree -- > each one has its own directory (with the exception of "base", which is glue > code for the whole collective algorithm framework). > > You probably want to look in the "tuned" component for OMPI's > current-generation algorithms (to be replaced soon, but that's what's mostly > used today). "tuned" has many different algorithm implementations for each > MPI collective, and uses sophisticated run-time checking to determine which > to use. > > So the answer to your original query -- how is the MPI_Allgather operation > done? -- is, "it depends" on things like message size, number of peers, > etc. :-) > > -- > 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 > http://www.open-mpi.org/mailman/listinfo.cgi/users >
