Flexible Priority Mechanism for Resolution of Multiple Requests to System Storage
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
In a controller system in which services are allocated to a plurality of input/output devices on a priority basis, the channel control element is designed to accept requests from many requesters, including an I/O Processor (IOP), a number of channels, and the channel subsystem timer. It must also accept storage requests of many different levels where the level is based on the identification (ID) of the requester and the type of request. It should also prevent any one requester from being forever "locked out" by higher priority requests from the other requesters. Finally, it should permit the priorities assigned to each requester to be set under software control which in turn permits the designers to "tune" the system as the system evolves through design, verification, test, and installation.