A Flexible Scheduler for the Andorra-I System

A flexible scheduler for distributing and- and or- parallel work in the Andorra-I system is presented. The scheduler allows workers to move freely between teams. Its strategy is based on estimates of and- and or- parallelism available in the execution tree. Preliminary results show that in most cases we can reach or surpass the best performance of Andorra-I running with any fixed team configuration. Since the teams are configured dynamically and automatically, the user does not need to be concerned with choosing an appropriate configuration. Further work is being done to improve the scheduler by using data obtained from compile-time analysis. Keywords: And/Or-parallelism, Multiprocessors, Scheduling. 1 Introduction There are two main sources of parallelism in logic programming, namely or- and andparallelism. Or- parallelism is exploited when several alternative clauses for a goal are executed in parallel. And- parallelism is exploited when we execute two or more goals of the same cla..