System and method for removing data from processor caches in a distributed multi-processor computer system

Abstract

A processor () in a distributed shared memory multi-processor computer system () may initiate a flush request to remove data from its cache. A processor interface () receives the flush request and performs a snoop operation to determine whether the data is maintained in a one of the local processors () and whether the data has been modified. If the data is maintained locally and it has been modified, the processor interface () initiates removal of the data from the cache of the identified processor (). The identified processor () initiates a writeback to a memory directory interface unit () associated with a home memoryfor the data in order to preserve the modification to the data. If the data is not maintained locally or has not been modified, the processor interface () forwards the flush request to the memory directory interface unit (). Memory directory interface unit () determines which remote processors within the system () have a copy of the data and forwards the flush request only to those identified processors. The identified processors then remove the data from their respective caches in response to the flush request. If an identified remote processor has modified data, the identified remote processor initiates a writeback to the memory directory interface unit () for preservation of the modified data.