Processor associated blocking symbol controls for serializing the

Abstract

Provides a processor CLE (CPU lock element) for each processor in a protected storage in a multi-processor computer system. Each CLE contains a blocking symbol field (called herein a PLT, program lock token, field), a lock field H, and a wait field W which is used to chain plural CLEs currently having the same blocking symbol. When the lock field H is set to a lock held state, it indicates the associated processor has exclusive rights to access a data resource unit associated with the blocking symbol in the CLE entry. When the wait field in a lock entry contains a pointer to another lock entry and the H field in the lock entry indicates a not held state, the associated processor is waiting for the resource and cannot further execute its PLO instance until it later gets set to the lock state, which is done by the processor of the prior CLE in the chain when it completes execution of its PLO instance. Each PLO instruction also has operand fields, and a function code (FC). The FC controls the manner of processing done by the PLO instance on its operands. Blocking symbols are specified by software to enable the software to utilize hardware enforced serialization of multi-processor accesses simultaneously requested for accessing the same data resource in the computer system. The plural processors may simultaneously, and at any time, initiate PLO instances for the same or different blocking symbols. When different processors simultaneously execute PLO instances having different blocking symbols, the processors may execute in parallel without conflict. But if the different processors simultaneously execute PLO instances having the same blocking symbol, the processors cannot execute in parallel without potential conflict, and the processors must serialize the execution of their PLO instances for accessing the same resource. In the latter case, their CLEs are chained through pointers in wait fields of the CLEs.