Local scheduling for distributed cooperation

The emergence of mobile computing paradigms has created new dimensions for the problem of performing a collection of tasks in a distributed setting. Indeed, an intrinsic feature of mobile computing is that the communication topology changes over time, and some devices may not be able to communicate with others for prolonged periods of time. Efficient utilization of resources in such a setting requires tools for structuring computation with highly variable, or absent, processor connectivity. This article provides a family of efficient distributed scheduling building blocks for this purpose. Specifically, this paper presents new bounds for a fundamental distributed cooperation problem under the assumption that processors may need to schedule their work in isolation due to a prolonged absence of communication. The problem for n processors is defined in terms of t tasks that must be performed efficiently and that are known to all processors. This study gives tight bounds on the ability of the processors to schedule their work so that when some group of processors establish communication, the wasted (redundant) work these processors have collectively performed prior to that time is controlled.