Extending snoopy cache consistency to general interconnection networks

Snoopy cache consistency is being used in many of today´s PCs and workstations to build cost-effective multiprocessors from commodity microprocessors. This paper presents an extension to snoopy cache consistency that allows extensible multiprocessors to be constructed using general-purpose interconnection networks with an extension of standard PC or workstation architectures. The scheme provides the efficiency of bus-based snoopy schemes with the scalability of directory-based schemes. The solution is inherently simple and makes no assumptions regarding the topology of the underlying network. The extension presented in this paper remains compatible with existing snoopy cache consistency allowing systems to be constructed using commodity PCs and workstations without modification