User Migration Guide: 1.8.x and v1.10.x to v2.0.0

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Open MPI User Migration Guide

Users should not treat this wiki page as definitive (YET). Please check back later.

User-Noticeable changes

I.e., things that may prevent users from simply re-compiling / re-mpirun'ing their existing MPI app.

• mpirun -np behavior
• OMPIO is now the default (not ROMIO)
• MPI C++ bindings are disabled by default
• ...more?

New features

• Launch scalability improvements (i.e., support for PMIx)
• Lots of improvements to MPI RMA
• Improved support for MPI_THREAD_MULTIPLE (when configured with --enable-mpi-thread-multiple)
• ompi_info pretty print improvements
• UCX support
• PLFS support (via OMPIO)
• Better Cray build / SLURM support
• ...more?

Removed support

• OS X Leopard
• Cray XT
• VampirTrace
• Myrinet MX / OpenMX
• coll:ml module
• Alpha processors
• --enable-mpi-profiling option
• Checkpoint / restart
• ...more?

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