[Beowulf] multi-threading vs. MPI

[Geoff Jacobs]

Toon Knapen wrote:
> Joe Landman wrote:
> 
>> Large cluster programming will always need an MPI or MPI-like system.
>> Small SMP programming might have easier to use alternatives that are
>> "good enough".  That "good enough" factor is not one to be discounted
>> lightly, you do so at your own peril.
> 
> 
> But what would be the advantages/disadvantages of both these
> technologies if one starts a new project now knowing that it will have
> to run in parallel and knowing that multi-core processors are
> increasingly Numa ?

Here are the advantages and disadvantages:
OpenMP is easy, but only works on one computer.
MPI requires more effort up front, but works across many computers.

In both cases, some careful thought has to be applied in partitioning
the problem to achieve good speedup, and even then the results can be mixed.

-- 
Geoffrey D. Jacobs