Patent ID: 6345341
Filing Date: 2002-02-05
Classification: G06F

Abstract:
A cache for use in a data processing system having a memory, a plurality of processing units coupled to an interconnect, and a plurality of caches that are each associated with a respective one of said plurality of processing units, said cache comprising:data storage including a plurality of data granules; a plurality of state fields associated with said plurality of data granules, wherein each state field among said plurality of state fields has a plurality of possible states including a first state indicating that an associated data granule is consistent with corresponding data in the memory and has unknown coherency with respect to a peer cache among the plurality of caches; and a cache controller that updates a particular state field among said plurality of state fields associated with a particular data granule among said plurality of data granules from said first state to another of said plurality of states in response to a snooped communication transaction on the interconnect.