Using Single Copy send/recv

• Set MPI_BUFFER_MAX to N
• any message with size > N bytes will be transferred by direct copy if
  • MPI semantics allow it
  • -64 ABI is used
  • the memory region it is allocated in is a globally accessible location
• N=2000 seems to work well
  • shorter messages don’t benefit from direct copy transfer method
• Look at stats to verify that direct copy was used.

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