Thanks for the quick reply Jeff. That information is valuable. I'll follow up on your pointers. Much appreciated, Tim. On Mar 26, 2013, at 12:32 PM, Jeff Hammond <[email protected]<mailto:[email protected]>> wrote: You might want to look at neighborhood collectives, which are discussed in Chapter 7 of MPI-3. This is a new feature so it may not be implemented in all MPI implementations, but MPICH supports it. I guess MVAPICH will support it soon enough if not already. When persistent MPI send/recv is discussed at the MPI Forum, it is often described as an inadequate solution because it does not specify a full channel and thus some important optimizations, e.g. for RDMA, may not be feasible. If you can use MPI-3 RMA, that is probably going to be a good idea, although high-quality support for RMA varies. MPICH-derived implementations usually do a good job though. Best, Jeff On Tue, Mar 26, 2013 at 11:25 AM, Timothy Stitt <[email protected]<mailto:[email protected]>> wrote: Hi all, I've been asking this question around various MPI boards to try and get a consensus before I decide to rewrite some MPI code. I am grateful for any advice that you can give. I've inherited a MPI code that was written ~8-10 years ago and it predominately uses MPI persistent communication routines for data transfers e.g. MPI_SEND_INIT, MPI_RECV_INIT, MPI_START etc. (which I am not familiar with and don't normally hear much discussion about). I was just wondering if using persistent communication calls is still regarded as the most efficient/scalable way to perform communication when the communication pattern is known and fixed amongst neighborhood processes? We regularly run the code across an IB network so would there be a benefit to rewrite the code using another approach (e.g. MPI one-sided communication) or should I leave it as it is? The code currently scales up to 10K cores and I want to push it even further and thus was wondering if there is any benefit in tinkering with this persistent MPI communication approach? Thanks in advance for any advice. Tim. _______________________________________________ discuss mailing list [email protected]<mailto:[email protected]> To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss -- Jeff Hammond Argonne Leadership Computing Facility University of Chicago Computation Institute [email protected]<mailto:[email protected]> / (630) 252-5381 http://www.linkedin.com/in/jeffhammond https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss Tim Stitt PhD User Support Manager (CRC) Research Assistant Professor (Computer Science & Engineering) Room 108, Center for Research Computing | University of Notre Dame | P.O. Box 539, Notre Dame, IN 46556 | Phone: 574-631-5287 | Email: [email protected]<mailto:[email protected]>