Lucene and fadvise/madviseWhile indexing, Lucene periodically merges multiple segments in the index into a single larger segment. This keeps the number of segments relatively contained (important for search performance), and also reclaims disk space for any deleted docs on those segments. However, it has a well known problem: the merging process evicts pages from the OS's buffer cache. The eviction is ~2X the size of the m
