Method and apparatus for extending cache history

A method comprising:

• receiving a request for access to a location that is not cached, said location being within a storage area of an underlying level of a memory hierarchy;
• selecting a cache entry;
• if the storage area is indicated by address information of a valid entry in a cache extender, recording historical information in the cache extender;
• and
• if the storage area is not indicated by address information of a valid entry in the cache extender, initializing an entry in the cache extender,
• wherein selecting a cache entry is based at least in part on historical information recorded in the cache extender,
• wherein initializing an entry in the cache extender comprises recording historical information in the cache extender, the historical information relating at least in part to requests for access to locations within the storage area related to the extender entry address information of the corresponding extender address portion, and
• wherein the cache extender historical information comprises historical information relating to requests for access to locations in the storage area no longer having corresponding entries in the cache.

A data storage medium having machine-readable code stored thereon, the machine-readable code comprising instructions executable by a machine, the instructions, when executed by a machine, causing:

• receiving a request for access to a location that is not cached, said location being within a storage area of an underlying level of a memory hierarchy;
• selecting a cache entry;
• if the storage area is indicated by address information of a valid entry in a cache extender, recording historical information in the cache extender;
• and
• if the storage area is not indicated by address information of a valid entry in the cache extender, initializing an entry in the cache extender,
• wherein selecting a cache entry is based at least in part on historical information recorded in the cache extender,
• wherein initializing an entry in the cache extender comprises recording historical information in the cache extender, and
• wherein the cache extender historical information comprises historical information relating to requests for access to locations in the storage area no longer having corresponding entries in the cache.

An integrated circuit, said circuit comprising an array of logic elements, said array being configured to perform a method comprising:

• receiving a request for access to a location that is not cached, said location being within a storage area of an underlying level of a memory hierarchy;
• selecting a cache entry;
• if the storage area is indicated by address information of a valid entry in a cache extender, recording historical information in the cache extender;
• and
• if the storage area is not indicated by address information of a valid entry in the cache extender, initializing an entry in the cache extender,
• wherein selecting a cache entry is based at least in part on historical information recorded in the cache extender,
• wherein initializing an entry in the cache extender comprises recording historical information in the cache extender, and
• wherein the cache extender historical information comprises historical information relating to requests for access to locations in the storage area no longer having corresponding entries in the cache.

An apparatus for extending cache history, comprising:

• a cache with a plurality of cache entries, each cache entry storing cache entry address information and cached data;
• a cache extender with a plurality of cache extender entries, each cache extender entry storing cache extender address information and cache extender auxiliary information;
• and
• an underlying memory;
• means for implementing a replacement strategy for said plurality of cache entries using at least said cache extender auxiliary information
• wherein the cache extender auxiliary information comprises historical information relating to requests for access to locations in the underlying memory that no longer have corresponding entries in the cache.

An apparatus for extending cache history, said apparatus comprising:

• a cache with a plurality of cache entries, each of said plurality of cache entries storing cache entry address information;
• a cache extender with a plurality of cache extender entries, each of said plurality of cache extender entries storing cache extender address information and cache extender auxiliary information;
• and
• an underlying memory;
• wherein said cache entry address information corresponds to one of said plurality of cache extender entries and said cache extender address information corresponds to a storage location of said underlying memory;
• wherein said cache extender auxiliary information is historical information, said historical information relating at least in part to the number of requests for access to said storage location of said underlying memory specified by said cache extender address information, and
• wherein said cache extender auxiliary information comprises historical information relating to requests for access to locations in underlying memory that no longer have corresponding entries in the cache.