Dear George, Dear all, A question regarding program design: The draft that I have sent to you has to be done many and many times. Does the splitting procedure ensure efficiency?
I will try, at a lest to create groups and split them. I am a beginner in the MPI groups environment. really, really thanks. You are my lifesaver. Diego On 26 July 2017 at 15:09, George Bosilca <bosi...@icl.utk.edu> wrote: > Diego, > > As all your processes are started under the umbrella of a single mpirun, > they have a communicator in common, the MPI_COMM_WORLD. > > One possible implementation, using MPI_Comm_split, will be the following: > > MPI_Comm small_comm, leader_comm; > > /* Create small_comm on all processes */ > > /* Now use MPI_Comm_split on MPI_COMM_WORLD to select the leaders */ > MPI_Comm_split( MPI_COMM_WORLD, > i_am_leader(small_comm) ? 1 : MPI_UNDEFINED, > rank_in_comm_world, > &leader_Comm); > > The leader_comm will be a valid communicator on all leaders processes, and > MPI_COMM_NULL on all others. > > George. > > > > On Wed, Jul 26, 2017 at 4:29 AM, Diego Avesani <diego.aves...@gmail.com> > wrote: > >> Dear George, Dear all, >> >> I use "mpirun -np xx ./a.out" >> >> I do not know if I have some common grounds. I mean, I have to >> design everything from the begging. You can find what I would like to do in >> the attachment. Basically, an MPI cast in another MPI. Consequently, I am >> thinking to MPI groups or MPI virtual topology with a 2D cart, using the >> columns as "groups" and the first rows as the external groups to handle the >> columns. >> >> What do think? What do you suggest? >> Really Really thanks >> >> >> Diego >> >> >> On 25 July 2017 at 19:26, George Bosilca <bosi...@icl.utk.edu> wrote: >> >>> Diego, >>> >>> Assuming you have some common grounds between the 4 initial groups >>> (otherwise you will have to connect them via >>> MPI_Comm_connect/MPI_Comm_accept) >>> you can merge the 4 groups together and then use any MPI mechanism to >>> create a partial group of leaders (such as MPI_Comm_split). >>> >>> If you spawn the groups via MPI_Comm_spawn then the answer is slightly >>> more complicated, you need to use MPI_Intercomm_create, with the spawner as >>> the bridge between the different communicators (and then >>> MPI_Intercomm_merge to create your intracomm). You can find a good answer >>> on stackoverflow on this at https://stackoverflow.com/ques >>> tions/24806782/mpi-merge-multiple-intercoms-into-a-single-intracomm >>> >>> How is your MPI environment started (single mpirun or mpi_comm_spawn) ? >>> >>> George. >>> >>> >>> >>> On Tue, Jul 25, 2017 at 10:44 AM, Diego Avesani <diego.aves...@gmail.com >>> > wrote: >>> >>>> Dear All, >>>> >>>> I am studying Groups and Communicators, but before start going in >>>> detail, I have a question about groups. >>>> >>>> I would like to know if is it possible to create a group of masters of >>>> the other groups and then a intra-communication in the new group. I have >>>> spent sometime reading different tutorial and presentation, but it is >>>> difficult, at least for me, to understand if is it possible to create this >>>> sort of MPI cast in another MPI. >>>> >>>> In the attachment you can find a pictures that summarize what I would >>>> like to do. >>>> >>>> Another strategies could be use virtual topology. >>>> >>>> What do you think? >>>> >>>> I really, really, appreciate any kind of help, suggestions or link >>>> where I can study this topics. >>>> >>>> Again, thanks >>>> >>>> Best Regards, >>>> >>>> Diego >>>> >>>> _______________________________________________ >>>> users mailing list >>>> users@lists.open-mpi.org >>>> https://rfd.newmexicoconsortium.org/mailman/listinfo/users >>>> >>> >>> >>> _______________________________________________ >>> users mailing list >>> users@lists.open-mpi.org >>> https://rfd.newmexicoconsortium.org/mailman/listinfo/users >>> >> >> >> _______________________________________________ >> users mailing list >> users@lists.open-mpi.org >> https://rfd.newmexicoconsortium.org/mailman/listinfo/users >> > > > _______________________________________________ > users mailing list > users@lists.open-mpi.org > https://rfd.newmexicoconsortium.org/mailman/listinfo/users >
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