International Business Machines Corporation
PREFETCH STORE PREALLOCATION IN AN EFFECTIVE ADDRESS-BASED CACHE DIRECTORY

Abstract:

In at least one embodiment, a processing unit includes a processor core and a vertical cache hierarchy including at least a store-through upper-level cache and a store-in lower-level cache. The upper-level cache includes a data array and an effective address (EA) directory. The processor core includes an execution unit, an address translation unit, and a prefetch unit configured to initiate allocation of a directory entry in the EA directory for a store target EA without prefetching a cache line of data into the corresponding data entry in the data array. The processor core caches in the directory entry an EA-to-RA address translation information for the store target EA, such that a subsequent demand store access that hits in the directory entry can avoid a performance penalty associated with address translation by the translation unit.