Equal access to prevent gateword dominance in a multiprocessor write-into-cache environment

摘要

In a multiprocessor write-into-cache data processing system including: a memory (3); at least first and second shared caches (4, 5); a system bus (11) coupling the memory (3) and the shared caches (4, 5); at least one processor (6P, 8P, 7P, 9P) having a private cache (8C) coupled to each shared cache (4, 5); method and apparatus for preventing hogging of ownership of a gateword (10) stored in the memory (3) which governs access to common code/data shared by processes running in the processors (6P, 8P, 7P, 9P) by which a read copy of the gateword is obtained by a given processor (8P) by performing successive swap operations. If the gateword is found to be OPEN, it is CLOSEd by the given processor (8P), and successive swap operations are performed to write the gateword CLOSEd in memory such that the given processor obtains exclusive access to the governed common code/data. When the given processor (8P) completes use of the common code/data, it writes the gateword OPEN in its private cache, and successive swap operations are performed to write the gateword OPEN in memory. <IMAGE>