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The Relative Worst Order Ratio Applied to Paging.
Joan Boyar, Lene M. Favrholdt, and Kim S. Larsen.
Journal of Computer and System Sciences, 73(5): 818-843, 2007.
The relative worst order ratio, a relatively new measure for the quality of on-line algorithms, is extended and applied to the paging problem. We obtain results significantly different from those obtained with the competitive ratio. First, we devise a new deterministic paging algorithm, Retrospective-LRU, and show that, according to the relative worst order ratio, it performs better than LRU. This is supported by experimental results, but contrasts with the competitive ratio. Furthermore, the relative worst order ratio (and practice) indicates that LRU is better than FWF, though all deterministic marking algorithms have the same competitive ratio. Look-ahead is also shown to be a significant advantage with this new measure, whereas the competitive ratio does not reflect that look-ahead can be helpful. Finally, as with the competitive ratio, no deterministic marking algorithm can be significantly better than LRU, but the randomized algorithm MARK is better than LRU.

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