Information processing apparatus, memory control method, and memory control device utilizing local and global snoop control units to maintain cache coherency

摘要

An information processing apparatus, a memory control method, and a memory control device are disclosed, the information processing apparatus including nodes each having a main memory, a processor including a cache memory, and a system controller. The system controller of at least one of the nodes includes a holding unit that holds address information corresponding to primary data stored in the main memory of its local node, and not cached in any of the cache memories of other nodes. The system controller of the at least one node may include local and global snoop control units, as well as a virtual tag expansion (VTAGx) unit, to maintain cache coherency, and under certain conditions, a snoop operation may be skipped or omitted.