[$] A hash table by any other name

On June 25, Matthew Wilcox posteda second version of a patch setintroducing a newdata structure called rosebush, which"is a resizing, scalable, cache-aware, RCU optimised hashtable." The kernel already has generic hash tables, though, includingrhashtable. Wilcox believes that the design ofrhashtable is not the best choice for performance, and has written rosebush asan alternative for use in thedirectory-entry cache (dcache) - the filesystem cache used to speed upfile-name lookup.