NON-UNIFORM MEMORY ACCESS (NUMA) DATA PROCESSING SYSTEM THAT PROVIDES PRECISE NOTIFICATION OF REMOTE DEALLOCATION OF MODIFIED DATA

A non-uniform memory access (NUMA) computer system includes a remote node coupled by a node interconnect to a home node including a home system memory. The remote node includes a plurality of snoopers coupled to a local interconnect. The plurality of snoopers includes a cache that caches a cache line corresponding to but modified with respect to data resident in the home system memory. The cache has a cache controller that issues a deallocate operation on the local interconnect in response to deallocating the modified cache line. The remote node further includes a node controller, coupled between the local interconnect and the node interconnect, that transmits the deallocate operation to the home node with an indication of whether or not a copy of the cache line remains in the remote node following the deallocation. In this manner, the local memory directory associated with the home system memory can be updated to precisely reflect which nodes hold a copy of the cache line.