Workshop:ExaMPI: Workshop on Exascale MPI
Authors: Jonathan Lifflander (Sandia National Laboratories), Phil Miller (Intense Computing), Nicole Lemaster Slattengren and Nicolas Morales (Sandia National Laboratories), and Paul Stickney and Philippe P. Pebay (NexGen Analytics)
Abstract: We present the execution model of Virtual Transport (VT) a new, asynchronous many-task (AMT) runtime system that provides unprecedented integration and interoperability with MPI. We have developed VT in conjunction with large production applications to provide a highly incremental, high-value path to AMT adoption in the dominant ecosystem of MPI applications, libraries and developers. Our aim is that the MPI+X model of hybrid parallelism can smoothly extend to become MPI+VT +X. We illustrate a set of design and implementation techniques that have been useful in building VT. We believe that these ideas and the code embodying them will be useful to others building similar systems, and perhaps provide insight into how MPI might evolve to better support them. We motivate our approach with two applications that are adopting VT and have begun to benefit from increased asynchrony and dynamic load balancing.