Since F C 00 a Comparison of List Schedules for Parallel Processing Table 7: the Speedup of Pyrros Code over the Sequential Ge Program on Ncube-2. 7 Conclusions

Empirical results have shown that the classical critical path (CP) list scheduling heuristic for task graphs is a fast and practical heuristic when communication cost is zero. In the rst part of this paper we study the theoretical properties of the CP heuristic that lead to near optimum performance in practice. In the second part we extend the CP analysis to the problem of ordering the task execution when the processor assignment is given and communication cost is nonzero. We propose two new list scheduling heuristics, the RCP and RCP that use critical path information and ready list priority scheduling. We show that the performance properties for RCP and RCP , when communication is nonzero, are similar to CP when communication is zero. Finally, we present an extensive experimental study and optimality analysis of the heuristics which veri es our theoretical results.