Two Fundamental Limits on Dataflow Multiprocessing

This paper examines the argument for dataflow architectures in “Two Fundamental Issues in Multiprocessing[5].” We observe two key problems. First, the justification of extensive multithreading is based on an overly simplistic view of the storage hierarchy. Second, the local greedy scheduling policy embodied in dataflow is inadequate in many circumstances. A more realistic model of the storage hierarchy imposes significant constraints on the scheduling of computation and requires a degree of parsimony in the scheduling policy. In particular, it is important to establish a scheduling hierarchy that reflects the underlying storage hierarchy. However, even with this improvement, simple local scheduling policies are unlikely to be adequate.