[Beowulf] Adding Latency to a Cluster Environment

Rusty Lusk lusk at mcs.anl.gov
Fri Feb 13 13:31:08 EST 2004


> Suggestions:
> - modify the routines that make MPI calls to call instead some wrapper 
> routines that do some thumb twiddling before making the MPI call; this 
> requires modification of the program source
> - modify the MPI routines (well, if you use an open-source MPI 
> implementation) to insert some delay, then relink your binary if static

With any standard-conforming MPI implementation, open-source or not, you
can use the MPI "profiling" interface to provide any kind of wrapper at
all.  Basically, you write your own MPI_Send, etc., which does whatever
you want and also calls PMPI_Send (required to be there) to do the real
work.  Then you link your routines in front of the MPI library, and
voila!

Cheers,
Rusty Lusk

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