Energy usage has been an important concern in recent research on online scheduling. In this paper we study the tradeoff between flow time and energy [1, 5, 7, 19] in the multi-processor setting. Our main result is an enhanced analysis of a simple non-migratory online algorithm called CRR (classified round robin) on m ≥ 2 processors, showing that its flow time plus energy is within O(1) times of the optimal non-migratory offline algorithm, when the maximum allowable speed is slightly relaxed.

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... result still holds even if the comparison is made against the optimal migratory offline algorithm. This improves previous analysis that CRR is O(log P )-competitive where P is the ratio of the maximum job size to the minimum job size. 0 A preliminary version of this