Efficient runtime support for parallelizing block structured applications

Scientific and engineering applications often involve structured meshes. These meshes may be nested (for multigrid codes) and/or irregularly coupled (called multiblock or irregularly coupled regular mesh problems). We describe a runtime library for parallelizing these applications on distributed memory parallel machines in an efficient and machine-independent fashion. This runtime library is implemented on several different systems. This library can be used by application programmers to port applications by hand and can also be used by a compiler to handle communication for these applications. Our experimental results show that our primitives have low runtime communication overheads. We have used this library to port a multiblock template and a multigrid code. Effort is also underway to port a complete multiblock computational fluid dynamics code using our library