Acta Informatica

, Volume 47, Issue 7–8, pp 359–374 | Cite as

A theoretical comparison of LRU and LRU-K

  • Joan Boyar
  • Martin R. Ehmsen
  • Jens S. Kohrt
  • Kim S. Larsen
Original Article


The paging algorithm Least Recently Used Second Last Request (LRU-2) was proposed for use in database disk buffering and shown experimentally to perform better than Least Recently Used (LRU). We compare LRU-2 and LRU theoretically, using both the standard competitive analysis and the newer relative worst order analysis. The competitive ratio for LRU-2 is shown to be 2k for cache size k, which is worse than LRU’s competitive ratio of k. However, using relative worst order analysis, we show that LRU-2 and LRU are comparable in LRU-2’s favor, giving a theoretical justification for the experimental results. Many of our results for LRU-2 also apply to its generalization, Least Recently Used Kth Last Request.


Competitive Ratio Online Algorithm Competitive Analysis Page Fault Theoretical Comparison 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Joan Boyar
    • 1
  • Martin R. Ehmsen
    • 1
  • Jens S. Kohrt
    • 1
  • Kim S. Larsen
    • 1
  1. 1.Department of Mathematics and Computer ScienceUniversity of Southern DenmarkOdense MDenmark

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