The advent of Exascale computing invites an assessment of existing best practices for developing application readiness on the world's largest supercomputers. This work details observations from the last four years in preparing scientific applications to run on the Oak Ridge Leadership Computing Facility's (OLCF) Frontier system. This paper addresses a range of topics in software including programmability, tuning, and portability considerations that are key to moving applications from existing systems to future installations. A set of representative workloads provides case studies for general system and software testing. We evaluate the use of early access systems for development across several generations of hardware. Finally, we discuss how best practices were identified and disseminated to the community through a wide range of activities including user-guides and trainings. We conclude with recommendations for ensuring application readiness on future leadership computing systems.

Abstract The design of the Parallel Ocean Program (POP) is described with an emphasis on portability. Performance of POP is presented on a wide variety of computational architectures, including vector architectures and commodity clusters. Analysis of POP performance across machines is used to characterize performance and identify improvements while maintaining portability. A new design of the POP model, including a cache blocking and land point elimination scheme, is described with some preliminary performance results. Published in 2005 by John Wiley & Sons, Ltd.

Oak Ridge National Laboratory installed a 32 processor Cray X1 in March, 2003, and will have a 256 processor system installed by October, 2003. In this paper we describe our initial evaluation of the X1 architecture, focusing on microbenchmarks, kernels, and application codes that highlight the performance characteristics of the X1 architecture and indicate how to use the system most efficiently.

Oak Ridge National Laboratory recently received 27 32-way IBM pSeries 690 SMP nodes. In this paper, we describe our initial evaluation of the p690 architecture, focusing on the performance of benchmarks and applications that are representative of the expected production workload.