Clustered computer system with deadlock avoidance

摘要

A remote resource management system for managing resources in a symmetrical multiprocessing environment having a plurality of clusters of symmetric multiprocessors each of which provides interfaces between cluster nodes of the symmetric multiprocessor system with a local interface and an interface controller. One or more remote storage controllers each has a local interface controller and a local-to-remote data bus. The system is provided with a remote resource manager for managing the interface between a plurality of clusters of symmetric multiprocessors each of which clusters has a plurality of processors, a shared cache memory, a plurality of I/O adapters and a main memory accessible from the cluster. A remote fetch controller is responsible for processing data accesses across the clusters and a remote store controller is responsible for processing data accesses across the clusters. These controllers work in conjunction to provide a deadlock avoidance system for preventing hangs which normally result from one resource on the local cluster waiting for a second resource on a remote cluster which is deadlocked against a third resource on said remote cluster waiting for a fourth resource on the local cluster which is deadlocked against said first resource on the local cluster. This system achieves deadlock avoidance when multiple nodes are processing simultaneous data access operations in which said data may be retrieved from a shared cache or shared memory, when multiple nodes are processing simultaneous data storage operations in which said data may involve processor storage operations to shared memory and/or memory storage operations resulting from casting out aged data.