Abstract
We present a performance modeling and programming environment for petaflops computers and the Blue Gene machine. It consists of a parallel simulator, BigSim, for predicting performance of machines with a very large number of processors, and BigNetSim, an ongoing effort to incorporate a pluggable module of a detailed contentionbased network model. It provides the ability to make performance predictions for machines such as BlueGene/L. We also explore the programming environments for several planned applications on the machines including Finite Element Method (FEM) simulation.