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MPI-3 Endpoints Proposal. Hybrid Working Group. Multiple MPI Processes per Address Space. MPI-2.2 already allows MPI processes to be implemented as more light-weight entities than OS processes Thus, we can have multiple MPI processes within an address space
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MPI-3 Endpoints Proposal Hybrid Working Group
Multiple MPI Processes per Address Space • MPI-2.2 already allows MPI processes to be implemented as more light-weight entities than OS processes • Thus, we can have multiple MPI processes within an address space • Could be pthreads, user-level threads, whatever • Two tickets: • Ticket #310: clarification and query functionality • Ticket #311: additional capabilities for interoperability with other programming models
Ticket #310 • Ticket #310 adds two parts • New options to mpiexec and SPAWN to start an MPI computation with multiple MPI processes within same address space • Allows applications to find which MPI processes are within the same address space • Impact on applications: • None, if do not plan to use multiple MPI processes within same address space • Applications/libraries can be written to be portable to such an environment • Impact on implementations: • None, if do not support new capability • Additional indirection in MPI calls, otherwise
Ticket #311 • Allow a thread to change its MPI rank to another rank within same address space • Impact on applications • Facilitate use of multiple MPI ranks within one OpenMP or UPC programs • Impact on implementations • None, if do not support multiple MPI processes within one address space • Very limited, once such a support is implemented