International Business Machines Corporation

Microsoft Technology Licensing, LLC

Sandra S Woodward

Eric Oliver Mejdrich

Russell Dean Hoover

Gerald George Pechanek

David James Shippy

Jon K Kriegel

James A Steenburgh

Mark C Snedaker

John Michael Borkenhagen

Bruce Leroy Beukema

J Andrew Goossen

Jeffrey Andrews

Nicholas Robert Baker

Duane Arlyn Averill

David Joel Verdoorn

Methods and apparatus for reducing the amount of latency involved when accessing, by a remote device, data residing in a cache of a processor are provided. For some embodiments, virtual channels may be utilized to conduct request/response transactions between the remote device and processor that satisfy a set of associated coherency rules.

Low latency coherency protocol for a multi-chip multiprocessor system

Methods for quickly accessing data residing in a cache of one processor, by another processor, while avoiding lengthy accesses to main memory are provided. A portion of the cache may be placed in a lock set mode by the processor in which it resides. While in the lock set mode, this portion of the cache may be accessed directly by another processor without lengthy 'backing' writes of the accessed data to main memory.

Direct access of cache lock set data without backing memory

A CPU module includes a host element configured to perform a high-level host-related task, and one or more data-generating processing elements configured to perform a data-generating task associated with the high-level host-related task. Each data-generating processing element includes logic configured to receive input data, and logic configured to process the input data to produce output data.

System and method for transfer of data between processors using a locked set, head and tail pointers

Methods and apparatus that may be utilized to maintain coherency of data accessed by both a processor and a remote device are provided. Various mechanisms, such as a remote cache directory, castout buffer, and/or outstanding transaction buffer may be utilized by the remote device to track the state of processor cache lines that may hold data targeted by requests initiated by the remote device. Based on the content of these mechanisms, requests targeting data that is not in the processor cache may be routed directly to memory, thus reducing overall latency.

Snoop filter directory mechanism in coherency shared memory system

In a first aspect, an apparatus is provided that is adapted to multiplex debug signals of an integrated circuit. The apparatus includes at least a first multiplexing circuit and a second multiplexing circuit. The first multiplexing circuit is adapted to receive first debug signals from the integrated circuit and to selectively multiplex at least a first portion of the first debug signals onto a first bus. The second multiplexing circuit is adapted to receive second debug signals from the integrated circuit and to selectively multiplex at least a first portion of the second debug signals onto a second bus. The apparatus further includes a logic circuit adapted to combine any debug signals of the first and second buses onto a third bus. An output stage of the apparatus is adapted to selectively output debug signals of the third bus. Numerous other aspects are provided, as are systems and methods.

Method and apparatus for debugging a chip

A method and apparatus are provided for detecting virtual address parity error for a translation lookaside buffer in a computer system. The computer system includes a processor unit, a cache coupled to the processor unit, a main memory, and a storage control unit including a translation lookaside buffer (TLB) and a segment lookaside buffer (SLB). A virtual address parity (VAP) is generated for each entry written in the segment lookaside buffer (SLB). A virtual address parity (VAP) is generated for each virtual address entry written in the translation lookaside buffer (TLB). The SLB virtual address parity (VAP) and the TLB virtual address parity (VAP) are utilized for identifying a translation miss condition.

Method and apparatus for detecting virtual address parity error for a

A method and apparatus are provided for communicating translation command information in a multithreaded environment in a computer system. The computer system includes a processor unit, an instruction unit coupled to the processor unit, a cache coupled to the processor unit, a main memory, and a storage control unit including a dataflow control partition, a cache control partition, a translation control partition. A translation miss signal is sent from the dataflow control partition to the translation control partition, responsive to detecting a translation miss condition. A translation command next signal is sent from the translation control partition to the cache control partition responsive to the translation miss signal. Then a translation command signal is sent from the translation control partition to the cache control partition. Responsive to the translation miss signal, a steal command signal is applied to the instruction unit for providing the translation command priority over execution of another thread. A series of the translation command signals are sent from the translation control partition to the cache control partition, and in one control cycle, the translation control partition can receive a translation command taken signal from the cache control partition for a translation command signal and can receive a translation data valid signal from the cache control partition for another translation command signal.

Method and apparatus for communicating translation command information

An input/output bus for a data processing system which has extended addressing capabilities and a variable length handshake which accommodates the difference delays associated with various sets of logic and a two part address field which allows a bus unit and channel to be identified. The various units can disconnect from the bus during internal processing to free the bus for other activity. The unit removes the busy signal prior to dropping the data lines to allow a bus arbitration sequence to occur without slowing down the bus.

Apparatus and method for extending a parallel synchronous data and

A synchronous parallel data bus particularly adapted for use in a data processing system where it is necessary to transfer data over long distances. The physical connection between communicating units includes a plurality of wires adapted to carry the parallel data signal and a wire which carries a clock signal to the remote unit. When data is transmitted from the remote unit to the base unit, the clock signal which originated at the base unit and was transmitted to the remote unit is 'turned around' and transmitted back to the base unit for use in receiving the data from the remote unit.

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Rochester, MN, United States of America

Sandra S Woodward