Scheduling chained multiprocessor tasks onto large multiprocessor system

In this paper, we proposed an effective approach for scheduling of multiprocessor unit time tasks with chain precedence on to large multiprocessor system. In this work, we considered splitable and non-splitable multiprocessor tasks, which is a new and interesting dimension to the generalized scheduling problem. The proposed longest chain maximum processor scheduling algorithm is proved to be optimal for uniform chains and monotone (non-increasing/non-decreasing) chains for both splitable and non-splitable multiprocessor unit time tasks chain. Scheduling arbitrary chains of non-splitable multiprocessor unit time tasks is proved to be NP-complete problem. But scheduling arbitrary chains of splitable multiprocessor unit time tasks is still an open problem to be proved whether it is NP-complete or can be solved in polynomial time. We have used three heuristics (a) maximum criticality first, (b) longest chain maximum criticality first and (c) longest chain maximum processor first for scheduling of arbitrary chains. We have also compared the performance of all three scheduling heuristics and found out that the proposed longest chain maximum processor first performs better in most of the cases. Also we have evaluated the performance of the mentioned heuristics by scheduling scientific work-flows on real multi-processor server platform and analyzed power and performance trade-off of the same scheduling policies.