SP2 Programming Tip

Observation:On the SP2, the speed of each communication link between processors in the same frame (nearby processors) is not significantly faster than between processors in different frames (distant processors).

Observation:There are less communication links between different frames than there are between processors in the same frame.

For parallel algorithms where only a few processors are communicating at any particular time, the actual location of processors that tasks are mapped to becomes less significant than in other parallel machines.
If many tasks are communicating at the same time, intra-frame communication links will be less loaded if tasks that frequently communicate with each other are mapped to processors in the same frame.

Unfortunately, the SP2 Parallel Operating Environment provides some, but little support, for specifically allocating tasks to processors.