Selective snooping by snoop masters to locate updated data

摘要

A system and structure for snooping cache memories of several snooping masters connected to a bus macro, wherein each non-originating snooping master has a cache memory, and wherein some, but less than all the cache memories, may have the data requested by an originating snooping master and wherein the needed data in an non-originating snooping master is marked as updated, and wherein a main memory having addresses for all data is connected to the bus macro. Only those non-originating snooping masters which may have the requested data are queried. All the non-originating snooping masters that have been queried reply. If a non-originating snooping master has the requested data marked as updated, that non-originating snooping master returns the updated data to the originating snooping master and possibly to the main memory. If none of the non-originating snooping masters has the requested data marked as updated, then the requested data is read from main memory.