A Lazy Scheduling Scheme for Improving Hypercube Performance

Processor allocation and job scheduling are com plementary techniques to improve the performance of multiprocessors. It has been observed that all the hypercube allocation policies with the FCFS schedul ing show little performance difference. A greater im pact on the performance can be obtained by efficient job scheduling. This paper presents an effort in that direction by introducing a new scheduling algorithm called lazy scheduling for hypercubes. The motivation of this scheme is to eliminate the limitations of the FCFS scheduling. This is done by maintaining sep arate queues for different job sizes and delaying the allocation of a job if any other job(s) of the same di mension is(are) running in the system. Simulation studies show that the hypercube performance is dra matically enhanced by using the lazy scheme as com pared to the FCFS scheduling. Comparison with a re cently proposed scheme called scan indicates that the lazy scheme performs better than scan under a wide range of workloads.