The method of claim 2, further comprising the steps of:
The method of claim 1 wherein said resources are memory storage locations and exclusive control is managed by a plurality of cache lines, each cache line controlling a plurality of storage locations.ģ. (c) once said global lock is controlled, repeating attempts to acquire the individual lock for each of said subset of said plurality of resources until successful.Ģ. (B) if said global lock is denied, releasing all individual locks and waiting until said global lock is available and (A) attempting the acquire said global lock
(3) if the individual lock for said resource is denied: (2) testing to determine if the individual lock for said resource is granted (1) attempting to acquire the individual lock for said resource (b) for each remaining resource of said subset of said plurality of resources (a) acquiring the individual lock for a first of said subset of said plurality of resources A method for preventing resource acquisition deadlock in a computer system having a plurality of disjoint resources, a plurality of processors, each processor executing instructions including instructions requiring exclusive control of a subset of said plurality of resources, said system having respective individual locks for acquiring exclusive control of said resources on an individual basis and a global lock for acquiring exclusive control of said plurality of resources on a global basis, with said global lock being controlled by at most one of said processors at a time, the method comprising the steps of: Synonym detection logic is provided to detect the situation where a conflict is caused by address resolution to a synonymous lock by the processor.ġ. However, an alternate embodiment which uses the global lock in each multiple resource instruction could also be implemented.
The preferred embodiment acquires the global lock on an exception basis to minimize the overhead impact. The use of a global lock serializes multiple resource requests and assures that the processor holding the lock can eventually acquire all required resources without deadlock with another processor. Upon conflict detection, the processor attempts to acquire the multi-resource instruction global lock and, if successful, resumes resource acquisition. A multi-resource instruction global lock is provided that can be held by at most one processor. The system detects potential deadlock situations where a multi-resource instruction is blocked from obtaining one of the resources. A system and method for preventing deadlock in a multiprocessor computer system executing instructions requiring multiple resources.
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