<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Thanks for the quick reply Jeff. That information is valuable. I'll follow up on your pointers.<div><br></div><div>Much appreciated,</div><div><br></div><div>Tim.<br><div><br><div><div>On Mar 26, 2013, at 12:32 PM, Jeff Hammond <<a href="mailto:jhammond@alcf.anl.gov">jhammond@alcf.anl.gov</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">You might want to look at neighborhood collectives, which are<br>discussed in Chapter 7 of MPI-3. This is a new feature so it may not<br>be implemented in all MPI implementations, but MPICH supports it. I<br>guess MVAPICH will support it soon enough if not already.<br><br>When persistent MPI send/recv is discussed at the MPI Forum, it is<br>often described as an inadequate solution because it does not specify<br>a full channel and thus some important optimizations, e.g. for RDMA,<br>may not be feasible.<br><br>If you can use MPI-3 RMA, that is probably going to be a good idea,<br>although high-quality support for RMA varies. MPICH-derived<br>implementations usually do a good job though.<br><br>Best,<br><br>Jeff<br><br>On Tue, Mar 26, 2013 at 11:25 AM, Timothy Stitt <<a href="mailto:Timothy.Stitt.9@nd.edu">Timothy.Stitt.9@nd.edu</a>> wrote:<br><blockquote type="cite">Hi all,<br><br>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.<br><br>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?<br><br>Thanks in advance for any advice.<br><br>Tim.<br><br>_______________________________________________<br>discuss mailing list <a href="mailto:discuss@mpich.org">discuss@mpich.org</a><br>To manage subscription options or unsubscribe:<br><a href="https://lists.mpich.org/mailman/listinfo/discuss">https://lists.mpich.org/mailman/listinfo/discuss</a><br></blockquote><br><br><br>-- <br>Jeff Hammond<br>Argonne Leadership Computing Facility<br>University of Chicago Computation Institute<br><a href="mailto:jhammond@alcf.anl.gov">jhammond@alcf.anl.gov</a> / (630) 252-5381<br><a href="http://www.linkedin.com/in/jeffhammond">http://www.linkedin.com/in/jeffhammond</a><br>https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond<br>_______________________________________________<br>discuss mailing list discuss@mpich.org<br>To manage subscription options or unsubscribe:<br>https://lists.mpich.org/mailman/listinfo/discuss<br></blockquote></div><br><div apple-content-edited="true">
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<strong style="color: rgb(255, 102, 0); font-weight: bold;">Tim
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