Hi Keita, There is no MPI API to do this from within an MPI application. One method I have used for this purpose is to create a function that executes an MPI_Comm_split operation using a string as a color value. As output, it returns a communicator containing all procs that specified the same string as the calling proc. To get a comm of all procs on the same node on a Linux system, I pass in the value of gethostname().
As an example, see scr_split.h/c from the SCR library at https://github.com/hpc/scr<https://github.com/hpc/scr.> That implementation uses a bitonic sort along with scan operations to execute the split. You can also accomplish this with hashing. If you need this type of functionality, I have a cleaned-up copy that I could send you without all of the SCR related code. -Adam ________________________________ From: users [users-boun...@open-mpi.org] on behalf of Ralph Castain [r...@open-mpi.org] Sent: Tuesday, November 25, 2014 2:38 PM To: Open MPI Users Subject: Re: [OMPI users] How to find MPI ranks located in remote nodes? Every process has a complete map of where every process in the job is located - not sure if there is an MPI API for accessing it, though. On Nov 25, 2014, at 2:32 PM, Teranishi, Keita <knte...@sandia.gov<mailto:knte...@sandia.gov>> wrote: Hi, I am trying to figure out a way for each local MPI rank to identify the ranks located in physically remote nodes (just different nodes) of cluster or MPPs such as Cray. I am using MPI_Get_processor_name to get the node ID, but it requires some processing to map MPI rank to the node ID. Is there any better ways doing this using MPI-2.2 (or earlier) capabilities? It will be great if I can easily get a list of MPI ranks in the same physical node. Thanks, ----------------------------------------------------------------------------- Keita Teranishi Principal Member of Technical Staff Scalable Modeling and Analysis Systems Sandia National Laboratories Livermore, CA 94551 +1 (925) 294-3738 _______________________________________________ users mailing list us...@open-mpi.org<mailto: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/2014/11/25868.php
