Affinity scheduling of unbalanced workloads

Abstract

Scheduling in shared memory multiprocessor is often complicated by the fact that a unit of work may be processed more efficiently on one processor than on any other, due to the factors such as the presence of required data in a local cache. The unit of work is said to have an 'affinity' for the given processor, in such a case. The scheduling issue that has to be considered is the tradeoff between the goals of respecting processor affinities and of dynamically assigning each unit of work to whichever processor happens to be, at the time, least loaded. In this paper, two new 'affinity scheduling' algorithms are proposed for a context in which the units of work have widely varying execution times. An experimental study of this algorithms finds them to perform well in this context.