Oracle International Corporation

Serena Leung

Ramaswamy Sivaramakrishnan

David Smentek

Mark Luttrell

Joann Lam

A cache memory that selectively enables and disables speculative reads from system memory is disclosed. The cache memory may include a plurality of partitions, and a plurality of registers. Each register may be configured to stored data indicative of a source of returned data for previous requests directed to a corresponding partition. Circuitry may be configured to receive a request for data to a given partition. The circuitry may be further configured to read contents of a register corresponding to the given partition, and initiate a speculative read dependent upon the contents of the register.

History based memory speculation for partitioned cache memories

A method and apparatus for performing non-temporal write combining using existing cache resources is disclosed. In one embodiment, a method includes executing a first thread on a processor core, the first thread including a first block initialization store (BIS) instruction. A cache query may be performed responsive to the BIS instruction, and if the query results in a cache miss, a cache line may be installed in a cache in an unordered dirty state in which it is exclusively owned by the first thread. The first BIS instruction and one or more additional BIS instructions may write data from the first processor core into the first cache line. After a cache coherence response is received, the state of the first cache line may be changed to an ordered dirty state in which it is no longer exclusive to the first thread.

Non-temporal write combining using cache resources

A method and apparatus for snooping caches is disclosed. In one embodiment, a system includes a number of processing nodes and a cache shared by each of the processing nodes. The cache is partitioned such that each of the processing nodes utilizes only one assigned partition. If a query by a processing node to its assigned partition of the cache results in a miss, a cache controller may determine whether to snoop other partitions in search of the requested information. The determination may be made based on history of where requested information was obtained from responsive to previous misses in that partition.

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South San Francisco, CA, United States of America

Serena Leung