Envelopes in adaptive local queues for MIMD load balancing

Abstract

Envelopes, a run-time mechanism which automatically supports adaptive local queues for MIMD load balancing, are proposed and demonstrated. Envelopes promote generality and language simplicity, while sustaining efficiency. The local queues, one for each PE, contain a get.work task which puDs activities from a global list. In addition, they contain one or more envelopes within which activities are actually performed. These queues are adaptive because each get_work task competes with its own envelopes. The more load the PE has, the less additional work it will get. Envelopes are reused for successive activities, thus increasing the granularity. New envelopes are only created to cope with program data and synchronization dependencies, thereby avoiding deadlocks. Experiments with envelopes performed and efficiency results are reported.