Multiple variable cache replacement policy

Abstract

A method for selecting a candidate to mark as overwritable in the event of a cache miss while attempting to avoid a write back operation. The method includes associating a set of data with the cache access request, each datum of the set is associated with a way, then choosing an invalid way among the set. Where no invalid ways exist among the set, the next step is determining a way that is not most recently used among the set. Next, the method determines whether a shared resource is crowded. When the shared resource is not crowded, the not most recently used way is chosen as the candidate. Where the shared resource is crowded, the next step is to determine whether the not most recently used way differs from an associated source in the memory and where the not most recently used way is the same as an associated source in the memory, the not most recently used way is chosen as the candidate. Where the not most recently used way differs from an associated source in the memory, the candidate is chosen as the way among the set that does not differ from an associated source in the memory. Where all ways among the set differ from respective sources in the memory, the not most recently used way is chosen as the candidate and the not most recently used way is stored in the shared resource.