Marvell International Limited

Jeffrey Kehl

Sujat Jamil

David E Miner

Tom Marko Hameenanttila

R Frank O'Bleness

Kim Richard Schuttenberg

Richard F Bryant

Joseph Anthony Delgross

Frank O'Bleness

Adi Habusha

A system and method of tracking multiple non-identification tagged requests in a system with multiple responders are disclosed. In one embodiment, an electronic memory system comprises a memory configured to implement a plurality of response queues, wherein one response queue is associated with one responder from a plurality of responders, and wherein a responder is a device capable of resolving the memory request. A tracking module is configured to assign identification information to a memory request that is received and store the identification information in one or more queues of the plurality of response queues; and to transmit the memory request to each responder that is associated with the one or more queues. A response module is configured to associate the identification information in the one or more queues with a response upon receiving the response from the one or more responders.

Method and apparatus for associating requests and responses with identification information

An apparatus including a snoop filter decoupled from a cache and an associated method for snoop filtering are disclosed. The snoop filter is decoupled from the cache such that the cache changes states of lines in the cache from a first state that is a clean state, such as an exclusive (E) state, to a second state that is not a clean state, such as a modified (M) state, without the snoop filter's knowledge. The snoop filter buffers addresses of replaced lines that are unknown to be clean until a write-back associated with the replacement lines occurs, or until actual states of the replaced lines are determined by the snoop filter generating a snoop. A multi-level cache system in which a reallocation or replacement policy is biased to favor replacing certain lines such as inclusive lines, non-temporal lines or prefetched lines that have not been accessed, is also disclosed.

Method and apparatus having a snoop filter decoupled from an associated cache and a buffer for replacement line addresses

A system and method of tracking multiple non-identification tagged requests in a system with multiple responders using one or more tracking queues. In some embodiments, the system and method may be implemented in a snoop filter covering multiple caches. In some embodiments, a data-less bus query may be used to update the status of a requested line.

Method and apparatus for data-less bus query

A processor includes a first level of cache memory and a first set of instructions configured to implement a first cache coherency protocol. The processor also includes a second set of instructions configured to implement a second cache coherency protocol and a cache coherency protocol selector having at least two choice-states. The processor further includes a cache coherency implementer configured to implement the first cache coherency protocol or the second cache coherency with respect to the first level of cache memory based on a selected choice-state of the cache coherency protocol selector.

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Chandler, AZ, United States of America

Jeffrey Kehl