Image Number 2 for United States Patent #5230070.
A multi-processor (MP) system having shared storage is provided with locking of exclusivity status and read only status in multi-processor caches. The multi-processor system includes a plurality of processors, a shared main storage and a storage control element (SCE). The storage control element includes a global access authorization table (GAAT). Locking of exclusivity status in multi-processor caches is accomplished by providing at each processor a local access authorization table (AAT) containing access status for recently used data blocks wherein the size of a data block is a multiple of cache line size. The access status of a block in the local access authorization table is checked when the block is to be accessed by a processor. Only if the access status for a block is not found in the local access authorization table is authorization to access the block requested from the storage control element.