Enabling Work Migration in CoMD to Study Dynamic Load Imbalance Solutions

Olga Pearce, David F. Richards, Hadia Ahmed, Rasmus W. Larsen

We have enabled work migration in the CoMD proxy application to study dynamic load imbalance. Proxy applications are developed to simplify studying parallel performance of scientific simulations and to test potential solutions for performance problems. However, proxy applications are typically too simple to allow work migration or to represent the load imbalance of their parent applications. To study the ability of load balancing solutions to balance work effectively, we enable work migration in one of the ExMatEx proxy applications, CoMD. We design a methodology to parameterize three key aspects necessary for studying load imbalance correction: 1) the granularity with which work can be migrated; 2) the initial load imbalance; 3) the dynamic load imbalance (how quickly the load changes over time). We present a study of the impact of flexibility in work migration in CoMD on load balance and the associated rebalancing costs for a wide range of initial and dynamic load imbalance scenarios.