Extra Legs On Toa Swan

ExtraLegsOnToaSwan is a way to describe the experience of running parallel codes using ScaLapack. The code is replicated on a number of processors, which each make the same call to a subroutine (sorry this is FORTRAN) all together. This looks to me (the user programmer) like one call to a library, but it is actually a call which will cause the processes to all work simultaneously on different parts of the data to get the result.

When all is well the swan glides smoothly, 9 or 16 or even 25 processors working together in harmony. Sometimes this is not the case. The swan's legs get tangled and back comes an error code.

-- JohnFletcher

Compare the Anatidae aphorism: "While all above is smooth and graceful, below the water we are paddling furiously..."

See also ExtraLegsOntoaDog

CategoryHumor