The cache of dentry structures. Under UNIX an entry in a particular directory must be searched for linearly, so even if the disk block containing the directory entry list is in-core, there is an associated cost. The dcache stores recent results of these searches which in general speeds up these disk searches by a large factor. Recent 2.3 work uses the dentries to allow multiple mounting, union mount, and more. The hardware data cache is usually referred to as the D-cache.