Mechanism for optimizing generation of commit-signals in a distributed shared-memory system

A method for optimizing generation of a commit signal in response to a local memory reference operation issued by a first processor of a first node in a distributed shared memory multiprocessor system having a hierarchical switch for interconnecting a plurality of nodes, each node comprising a local switch interconnecting at least one local processor with the hierarchical switch, each processor employing a cache apportioned into a plurality of cache lines, the method comprising the steps of:

• providing a data structure at the first node that optimizes generation of the commit signal by storing information that indicates whether the memory reference operation issued by the first processor affects any non-local processor of the system, the memory reference operation affecting a non-local processor if the operation has a probe generated by an ordering point of the local switch at the first node;
• creating an entry in the data structure for the memory reference operation in response to the operation having a probe that is transmitted to and currently outstanding at the hierarchical switch, the probe configured to invalidate a copy of data associated with the operation that is stored in the cache of a non-local processor, the entry storing an address of a cache line for the outstanding probe;
• and
• optimizing generation of the commit signal at the first node when there is no entry in the data structure associated with the memory reference operation.