A Library for Advanced Datatype Programming

Abstract

We present a library providing functionality beyond the MPI standard for manipulating application data layouts described by MPI derived datatypes. The main contributions are: a) Constructors for several, new datatypes for describing application relevant data layouts. b) A set of extent-free constructors that eliminate the need for type resizing. c) New navigation and query functionality for accessing individual data elements in layouts described by datatypes, and for comparing layouts. d) Representation of datatype signatures by explicit, associated signature types, as well as functionality for explicit generation of type maps. As a simple application, we implement reduction collectives on noncontiguous, but homogeneous derived datatypes. Some of the proposed functionality could be implemented more efficiently within an MPI library.