Patent ID: 7222220

Claim:
A multiprocessing system comprising: a plurality of processing subsystems, each including a cache memory; a memory subsystem including a directory; a network interconnecting said plurality of processing subsystems and said memory subsystem; wherein the network includes a mode unit separate from the processing subsystems and the memory subsystem, the mode unit being configured to store an indication of whether a given block is a point-to-point mode block or a broadcast mode block, wherein the network is configured to: receive a given coherency request initiated by a requesting processing subsystem, wherein the given coherency request is not visible to other processing subsystems or the memory subsystem; and control, in accordance with said indication, whether the given coherency request is transmitted through said network according to a directory protocol or a broadcast protocol; and wherein an encoding of said given coherency request excludes an indication of whether said given coherence request is to be transmitted according to said directory protocol or said broadcast protocol; and wherein when said coherency request is transmitted through said network according to said directory protocol, said given coherency request is transmitted through said network to only said memory subsystem.