WorldSciNet

The dominant trend in scientific computing today is the establishment of platforms that span multiple institutions to support applications at unprecedented scales. On most distributed computing platforms a requirement to achieve high performance is the careful scheduling of distributed application components onto the available resources. While scheduling has been an active area of research for many decades most of the platform models traditionally used in scheduling research, and in particular network models, break down for platforms spanning wide-area networks. In this paper we examine network modeling issues for large-scale platforms from the perspective of scheduling. The main challenge we address is the development of models that are sophisticated enough to be more realistic than those traditionally used in the field, but simple enough that they are still amenable to analysis. In particular, we discuss issues of bandwidth sharing and topology modeling. Also, while these models can be used to define and reason about realistic scheduling problems, we show that they also provide a good basis for fast simulation, which is the typical method to evaluate scheduling algorithms, as demonstrated in our implementation of the SIMGRID simulation framework.