Dynamic cost modelling and load balancing for mesh-based applications

The DRAMA project is a European Commission (ESPRIT)-funded project which has been initiated to support the take-up of large scale parallel simulation in industry by dealing with one of the main problems which restricts the use of message-passing simulation codes the inability to perform dynamic load balancing. A concentration on message-passing parallelisation corresponds to the target of addressing large scale and thus highly scalable parallel applications. The central product of the project will be a library comprising various tools for dynamic repartitioning of unstructured finite element applications. The particular focus of the project is on the requirements of industrial Finite Element codes, with library evaluation and validation being performed using industrial software packages, but codes using Finite Volume formulations will also be able to make use of the project results. The core library functions will perform a parallel computation of a mesh re-allocation that will re-balance the costs of the application code based on the DRAMA cost model. This paper will discuss the design features of the library, which allow a general approach to load identification, modelling and minimisation. Results will be presented which both justify the inclusion of single-phase/uni-constraint graph partition components and point ahead to the requirements for multi-phase/multi-constraint versions.