Performance prediction using simulation of large-scale interconnection networks in pose

Parallel discrete event simulation (PDES) of mod-els with fine-grained computation remains a challeng-ing problem. We explore the usage of POSE, our Par-allel Object-oriented Simulation Environment, for ap-plication performance prediction on large parallel ma-chines such as BlueGene. This study involves the sim-ulation of communication at the packet level through a detailed network model. This presents an extremely fine-grained simulation: events correspond to the trans-mission and receipt of packets. Computation is minimal, communication dominates, and strong dependencies be-tween events result in a low degree of parallelism. There is limited look-ahead capability since the outcome of many events is determined by the application whose per-formance the simulation is predicting. Thus conservative synchronization approaches are challenging for this type of problem. We present recent experiences and perfor-mance results for our network simulator and illustrate the utility of our simulator through prediction and vali-dation studies for a molecular dynamics application.1 1