Dynamic hardware and software performance optimizations for super-coherent SMP systems

摘要

A method for increasing performance optimization in a multiprocessor data processing system. A number of predetermined thresholds are provided within a system controller logic and utilized to trigger specific bandwidth utilization responses. Both an address bus and data bus bandwidth utilization are monitored. Responsive to a fall of a percentage of data bus bandwidth utilization below a first predetermined threshold value, the system controller provides a particular response to a request for a cache line at a snooping processor having the cache line, where the response indicates to a requesting processor that the cache line will be provided. Conversely, if the percentage of data bus bandwidth utilization rises above a second predetermined threshold value, the system controller provides a next response to the request that indicates to any requesting processors that the requesting processor should utilize super-coherent data which is currently within its local cache. Similar operation on the address bus permits the system controller to triggering the issuing of Z1 Read requests for modified data in a shared cache line by processors which still have super-coherent data. The method also comprises enabling a load instruction with a plurality of bits that (1) indicates whether a resulting load request may receive super-coherent data and (2) overrides a coherency state indicating utilization of super-coherent data when said plurality of bits indicates that said load request may not utilize said super-coherent data. Specialized store instructions with appended bits and related functionality are also provided.