1. An apparatus comprising: a plurality of cores, the plurality of cores logically grouped into a plurality of clusters; and a cluster sharing map-based coherence directory coupled with the plurality of cores to track sharing of data among the plurality of cores, the cluster sharing map-based coherence directory including: a tag array to store corresponding pairs of addresses and cluster identifiers, each of the addresses to identify data, each of the cluster identifiers to identify one of the clusters; and a cluster sharing map array to store cluster sharing maps, each of the cluster sharing maps corresponding to one of the pairs of addresses and cluster identifiers, each of the cluster sharing maps to indicate intra-cluster sharing of data identified by the corresponding address within a cluster identified by the corresponding cluster identifier.