Interprocessor collective communication library (InterCom)

We outline a unified approach for building a library of collective communication operations that performs well on a cross-section of problems encountered in real applications. The target architecture is a two-dimensional mesh with worm-hole routing, but the techniques also apply to higher dimensional meshes and hypercubes. We stress a general approach, addressing the need for implementations that perform well for various sized vectors and grid dimensions, including non-power-of-two grids. This requires the development of general techniques for building hybrid algorithms. Finally, the approach also supports collective communication within a group of nodes, which is required by many scalable algorithms. Results from the Intel Paragon system are included