Modelling continuum mechanics phenomena using three dimensional unstructured meshes on massively parallel processors

The difficulties encountered in implementing large scale CM codes on multiprocessor systems are now fairly well understood. Despite the claims of shared memory architecture manufacturers to provide effective parallelizing compilers, these have not proved to be adequate for large or complex programs. Significant programmer effort is usually required to achieve reasonable parallel efficiencies on significant numbers of processors. The paradigm of Single Program Multi Data (SPMD) domain decomposition with message passing, where each processor runs the same code on a subdomain of the problem, communicating through exchange of messages, has for some time been demonstrated to provide the required level of efficiency, scalability, and portability across both shared and distributed memory systems, without the need to re-author the code into a new language or even to support differing message passing implementations. Extension of the methods into three dimensions has been enabled through the engineering of PHYSICA, a framework for supporting 3D, unstructured mesh and continuum mechanics modeling. In PHYSICA, six inspectors are used. Part of the challenge for automation of parallelization is being able to prove the equivalence of inspectors so that they can be merged into as few as possible.

Software tools for automating the parallelisation of FORTRAN computational mechanics codes

It is now clear that the concept of a HPC compiler which automatically produces highly efficient parallel implementations is a pipe-dream. Another route is to recognise from the outset that user information is required and to develop tools that embed user interaction in the transformation of code from scalar to parallel form, and then use conventional compilers with a set of communication calls. This represents the key idea underlying the development of the CAPTools software environment. The initial version of CAPTools is focused upon single block structured mesh computational mechanics codes. The capability for unstructured mesh codes is under test now and block structured meshes will be included next. The parallelisation process can be completed rapidly for modest codes and the parallel performance approaches that which is delivered by hand parallelisations.