Implementation and performance evaluation of the LRFU replacement policy

Recently, a new block replacement policy called the LRFU (Least Recently/Frequently Used) policy was proposed that subsumes both the LRU and LFU policies, and provides a spectrum of replacement policies between them. We describe an implementation of the LRFU replacement policy in the FreeBSD 2.1.5 and present a performance evaluation of the implementation using the SPEC SDET benchmark. The results show that the new policy gives up to a 30% performance improvement over the LRU block replacement policy.