Snoop filter with stored replacement information, method for same, and system including victim exclusive cache and snoop filter shared replacement policies

Abstract

Embodiments of the present system and method provide cache replacement in a victim exclusive cache using a snoop filter where replacement information is not lost during a re-reference back to the CPU. Replacement information is stored in a snoop filter, meaning that historical access data may be fully preserved and allows for more flexibility in the LLC re-insertion points, without additional bits stored in a L2 cache. The present system and method further include snoop filter replacement technique. The present system and method passes replacement information between a snoop filter and a victim exclusive cache (e.g., LLC) when transactions move cachelines to and from a master CPU. This maintains and advances existing replacement information for a cacheline that is removed from the victim exclusive cache on a read, as well as intelligently replaces and ages cachelines in the snoop filter.