Oracle America, Inc.

S3 Incorporated, Inc.

Srinivasan R Iyengar

Prashant Jain

Sanjay Patel

Yoganand Chillarige

Sandip Das

Shukur Moulali Pathan

Kenneth D Wagner

Mehran Amerian

Jeffrey Thomas Oplinger

A processor may include several processor cores, each including a respective higher-level cache; a lower-level cache including several tag units each including several controllers, where each controller corresponds to a respective cache bank configured to store data, and where the controllers are concurrently operable to access their respective cache banks; and an interconnect network configured to convey data between the cores and the lower-level cache. The controllers in a given tag unit may share access to a resource that may include one or more of an interconnect egress port coupled to the interconnect network, an interconnect ingress port coupled to the interconnect network, a test controller, or a data storage structure.

Resource sharing to reduce implementation costs in a multicore processor

A processor may include several processor cores, each including a respective higher-level cache; a lower-level cache including several tag units each including several controllers, where each controller corresponds to a respective cache bank configured to store data, and where the controllers are concurrently operable to access their respective cache banks; and an interconnect network configured to convey data between the cores and the lower-level cache. The controllers may share access to an interconnect egress port coupled to the interconnect network, and may generate multiple concurrent requests to convey data via the shared port, where each of the requests is destined for a corresponding core, and where a datapath width of the port is less than a combined width of the multiple requests. The given tag unit may arbitrate among the controllers for access to the shared port, such that the requests are transmitted to corresponding cores serially rather than concurrently.

A processor may include a writeback configured to perform a first writeback operation to store corresponding writeback data back to a lower-level memory upon eviction of the writeback data, and a writeback buffer configured to store the writeback data after the writeback data has been evicted from the writeback cache and before the writeback data has been sent to the lower-level memory. After the writeback data has been sent from the writeback buffer to the lower-level memory, and before the lower-level memory has acknowledged completion of the first writeback operation, the writeback cache may perform a second writeback operation to store different writeback data in the writeback buffer in response to eviction of the different writeback data, such that a total size of the writeback data for the concurrently outstanding writeback operations exceeds a total size of writeback data that the writeback buffer is capable of concurrently storing.

Processor and method for writeback buffer reuse

An improved scan flip-flop and method of using same. The scan flip-flop has a separate dedicated scan output driven by a scan output signal driver. Scan shift race conditions are minimized by providing a weak scan output signal driver and inserting delay elements within a cell for a scan flip-flop in the scan signal path. The use of the improved scan flip-flop allows for a one-pass scan synthesis process which provides accurate flip-flop cell timing and area information during the design process.

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Fremont, CA, United States of America

Srinivasan R Iyengar