[Beowulf] Performance characterising a HPC application

Patrick Geoffray patrick at myri.com
Wed Mar 28 22:43:43 PDT 2007

Hi Richard,

Richard Walsh wrote:
>     It is useful in a message context in the same way the vector
> instructions are useful in a memory
>     reference context.  Automatic "message" aggregation is an
> optimization technique being
>     used in UPC compiler development.

Message aggregation would be much more beneficial in the context of UPC, 
where the compiler will likely generates many small grain communications 
to the same remote process. However, as Greg pointed out, MPI 
applications often already aggregate messages themselves (this is 
something even "challenged" application people understand easily).

I would bet that UPC could more efficiently leverage a strided or vector 
communication primitive instead of message aggregation. I don't know if 
GasNet provides one, I know ARMCI does.

Patrick Geoffray
Myricom, Inc.

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