An Optimistic Approach to Computational Steering

Computational steering is the online, interactive allocation of resources and adjustment of application parameters. Although several systems for steering distributed computations have been developed, few support the coordinated steering of multiple processes. Of those that do provide such support, most take a conservative approach. Our system is unique in its optimistic approach. Coordinated steering of either type has the potential to introduce significant perturbation. We focus on optimistic steering, which does not require global synchronization before a steering event may take place. Such an approach requires both the ability to determine the consistency of steering transactions and the ability to correct any inconsistencies that may occur. To address these issues, we have developed algorithms for consistency detection and a steering system that has the ability to correct inconsistencies through computational rollback and re-execution. Presented in this paper are the details of our steering system and a performance analysis of that system.