EXCLUSIVE ACCESS CONTROL SYSTEM FOR SHARED RESOURCES

PURPOSE:To improve the throughput by constituting the system so that when a certain processor accesses shared resources, a system bus is not locked but only the part which becomes an object of the access is locked. CONSTITUTION:As for shared resources 16 and 17, whether they are monopolized by a certain processor or not is managed by a control mechanism 18. Also, in resources 14, exclusive resources 44 which can be accessed from only a specific processor are provided. A control mechanism 18 and 19 control locking and unlocking of the resources 14 and 15, respectively. An access to the resources 16, 17 takes a form of an instruction 1 - updating - an instruction 2 such as read-out, updating, and write. That is, by a first instruction 1, the accessed part is locked, and by the instruction 2, locking is released. Therefore, the instruction 1 and the instruction 2 become an access with locking and an access with unlocking, respectively.