Processing cache evictions in a directory snoop filter with ecam

Abstract

Techniques for maintaining cache coherency while sharing data among multiple processors are disclosed. Multiple coherent elements are arranged in an M×N mesh topology. An element can include a compute coherency block (CCB), and a coherency ordering agent (COA). The COAs include a directory snoop filter (DSF), an eviction content addressable memory (eCAM), a miss and snoop queue (MSQ), and a pipeline logic. The CCB and COA include functions for interfacing with a hierarchical cache and directory snoop filter (DSF). A CCB from within one of the multiple coherent elements issues a read request. The corresponding directory snoop filter (DSF) is inspected to determine if there is a slot (way) available for storing information pertaining to the read request. In the event that no eligible vacancies are present in the DSF, a multi-pass process for handling a capacity limit in a DSF is performed.