I have a section of code were I need to send 8 separate integers via
Initially I was just putting the 8 integers into an array and then
sending that array.
I just tried using MPI_PACK on those 8 integers and I'm seeing a
massive slow down in the code, I have a lot of other communication
and this section is being used only 5 times. I went from 140 seconds
to 277 seconds on 16 processors using TCP via a dual gigabit ethernet
setup (I'm the only user working on this system today).
This was run with OpenMPI 1.1.2 to maintain compatibility with a
major HPC site.
Is there a know problem with MPI_PACK/UNPACK in OpenMPI?