Distributed-directory scheme: scalable coherent interface

The scalable coherent interface (SCI), a local or extended computer backplane interface being defined by an IEEE standard project (P1596), is discussed. the interconnection is scalable, meaning that up to 64 K processor, memory, or I/O nodes can effectively interface to a shared SCI interconnection. The SCI sharing-list structures are described, and sharing-list addition and removal are examined. Optimizations being considered to improve the performance of large system configurations are discussed. Request combining, a useful feature of linked-list coherence, is described. SCI's optional extensions, including synchronization using a queued-on-lock bit, are considered.<>