Job Scheduling in Rings

We give distributed approximation algorithms for job scheduling in a ring architecture. In contrast to almost all other parallel scheduling models, the model we consider captures the influence of the underlying communications network by specifying that task migration from one processor to another takes time proportional to the distance between those two processors in the network. As a result, our algorithms must balance both computational load and communication time. The algorithms are simple, require no global control, and work in a variety of settings. All come with small constant-factor approximation guarantees; the basic algorithm yields schedules of length at most 4.22 times optimal. We also give a lower bound on the performance of any distributed algorithm some results for a simple capacitated case, and the results of simulation experiments, which give better results than our worst-case analysis