Khalid, The decision is rechecked every time we create a new communicator. So, you might create a solution that force the algorithm to whatever you think it is best (using the environment variables you mentioned), then create a communicator, and free it once you’re done.
I have no idea what you’re trying to achieve, but be aware there is a burden associated with the creation of a communicator, so this approach might outweigh the benefits. George. > On Mar 10, 2015, at 10:31 , Gilles Gouaillardet > <gilles.gouaillar...@gmail.com> wrote: > > Khalid, > > i am not aware of such a mechanism. > > /* there might be a way to use MPI_T_* mechanisms to force the algorithm, > and i will let other folks comment on that */ > > you definetly cannot directly invoke ompi_coll_tuned_bcast_intra_binomial > (abstraction violation, non portable, and you miss the some parameters) > > out of curiosity, what do you have in mind for (some_condition) ? > /* since it seems implicit (some_condition) is independant of communicator > size, and message size */ > > Cheers, > > Gilles > > On Tue, Mar 10, 2015 at 10:04 PM, Khalid Hasanov <xali...@gmail.com > <mailto:xali...@gmail.com>> wrote: > Hello, > > I would like to know if Open MPI provides some kind of mechanism to select > collective algorithms such as MPI broadcast during run time depending on some > logic. For example, I would like to > use something like this: > > if (some_condition) ompi_binomial_broadcast(...); > else ompi_pipeline_broadcast(...); > > I know it is possible to use some fixed algorithm by > coll_tuned_use_dynamic_rules or to define a custom selection rule using > coll_tuned_dynamic_rules_filename. But > I think it is not suitable in this situation as the dynamic rules mainly > based on the message size, segment size and communicator size. > > Another option could be using Open MPI internal APIS like > > ompi_coll_tuned_bcast_intra_binomial( buf, count, dtype, root, comm, module, > segsize); > > But it highly depends on Open MPI internals as it uses mca_coll_base_module_t > . > > Is there any better option? (except using my own implementation of > collectives) > > Any suggestion highly appreciated. > > Thanks > > Regards, > Khalid > > _______________________________________________ > users mailing list > us...@open-mpi.org <mailto:us...@open-mpi.org> > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > <http://www.open-mpi.org/mailman/listinfo.cgi/users> > Link to this post: > http://www.open-mpi.org/community/lists/users/2015/03/26446.php > <http://www.open-mpi.org/community/lists/users/2015/03/26446.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/2015/03/26447.php
