An approach for deploying externally defined MPI communicators at runtime
Carsten Clauß, Thomas Bemmerl, Stefan Lankes, Stefan Gsell · RWTH Publications (RWTH Aachen) · 2007
When writing parallel applications according to the MPI standard especially for hierarchical computing environments, the recognition of the underlying heterogeneous hardware structure at application level is not trivial at all. Although the MPI standard tries to support the application programmer with some process grouping and mapping facilities (notably the communicator concept and the topology mechanism), the actual hardware hierarchy is usually still kept opaque. In this paper, we present a generalized approach that allows the programmer to create suitable process groups according to the given topologies by externally defining MPI communicators in corresponding XML files. We further introduce a small external library for MPI implementations that is able to parse those XML files and can build the desired communicators at runtime. That way, the actual hardware hierarchy becomes visible also at application level.