A computer system with a processor cache that stores remote cache presence
information. In one embodiment, a plurality of presence vectors are
stored to indicate whether particular blocks of data mapped to another
node are being remotely cached. Rather than storing the presence vectors
in a dedicated storage, the remote cache presence vectors may be stored
in designated locations of a cache memory subsystem, such as an L2 cache,
associated with a processor core. For example, a designated way of the
cache memory subsystem may be allocated for storing remote cache presence
vectors, while the remaining ways of the cache are used to store normal
processor data. New data blocks may be remotely cached in response to
evictions from the cache memory subsystem. In yet a further embodiment,
additional entries of the cache memory subsystem may be used for storing
directory entries to filter probe command and response traffic.