Blocking symbol control in a computer system to serialize accessing a

Abstract

PLO (perform locked operation) instructions containing blocking symbols are executed on each of multiple processors in a computer system to control coherence in data structures which may be changed by any of multiple processors in a computer system. The blocking symbol is extracted from a PLO instruction instance when invoked by its executing processor. Then the processor hashes the blocking symbol using hardware-microcode (H-M) to generate the location of a lock field in protected storage. The PLO instruction's blocking symbol is associated with a computer resource unit by software providing the PLO instruction, and the blocking symbol then associates the resource with a protected lock through the hashing operation on the blocking symbol. A processor must obtain the lock for a blocking symbol before the executing PLO instruction instance is allowed to make access and change the resource unit associated with the blocking symbol. The blocking symbol controls the PLO operations by serializing simultaneously PLO instruction access requests being made by multiple processors to the same resource unit using the same blocking symbol to allow only one PLO instruction instance to have exclusive access to the resource at a time.