Scalability of the Directory Entry Cache

This paper presents work that we have done to improve scalability of the directory entry cache (dcache). We investigated scalability problems resulting from many cache lookups, global lock contention, a possibly non-optimal eviction policy, and cacheline bouncing due to global reference counters. This paper provides an overview of solutions we tried, such as fast path walking, utilizing the read-copy update mutual exclusion mechanism, and lazy updating of the LRU list of dentries. We conclude with performance results showing scalability improvements.

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