Intone — Tools and Environments for OpenMP on Clusters of SMPs1

Clusters of small-scale SMP computers are becoming more and more common as high-performance computing needs have arised, not only in national scientific laboratories, but also in enterprises of various kinds. An SMP-cluster represents a sweet-spot of cost-efficiency compared to a larger SMP system or to a cluster with smaller nodes. With the emergance of OpenMP, shared memory computing has also become mainstream in the parallel computing world. Unfortunately, clusters of SMPs do not directly support a shared memory programming model in hardware and software distributed shared memory (DSM) techniques must be adopted in order to run OpenMP on a cluster of SMP as well as on, e.g., a high-end Sun Enterprise server. This abstract describes a research project which has been initiated to alleviate some of the problems of running OpenMP applications on clusters of SMPs. The acronym Intone stands for Innovative Tools for Non-Experts. Although OpenMP is not stated in the project title, it is an integral part of the approach taken in the project. Some of the goals of Intone are to: • Develop a graphical performance analysis system for OpenMP (both Fortran and C/C++) applications • To investigate the possibility of extending OpenMP with explicit message-passing primitives for performance critical communication • To advance the state-of-the-art of implementations of OpenMP for clusters of SMPs with software DSM • To evaluate the performance analysis system, the OpenMP extensions and the OpenMP-specific software DSM system with production parallel applications I will here briefly describe the activities in the project for the first three goals. Figure 1 shows the relationship between the software components in the envisioned system. The parts that Intone will deal with are underlined. Parallel applications are developed in a cyclic fashion. From a sequential program a parallel version is created either manually or automatically by parallelising tools such as the MIPSpro compiler from SGI or the KAP toolset [3, 7]. This code will be compiled with OpenMP compilers developed within the 1. INTONE is a project proposal tentatively financed by the European Commission under Framework Programme 5/IST. Contract negotiations are being carried out.