Keith N Langston

US Patent:

7475193, Jan 6, 2009

Filed:

Jan 18, 2006

Appl. No.:

11/334280

Inventors:

David S. Hutton - Poughkeepsie NY, US
Kathryn M. Jackson - Poughkeepsie NY, US
Keith N. Langston - Woodstock NY, US
Pak-kin Mak - Poughkeepsie NY, US
Bruce Wagar - Tempe AZ, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 12/00

US Classification:

711130, 711122

Abstract:

A dual system shared cache directory structure for a cache memory performs the role of an inclusive shared system cache, i. e. , data, and system control, i. e. , coherency. The system includes two separate system cache directories in the shared system cache. The two separate cache directories are substantially equal in size and collectively large enough to contain all of the processor cache directory entries, but with only one of these separate cache directories hosting system-cache data to back the most recent fraction of data accessed by the processors. The other cache directory retains only addresses, including addresses of lines LRUed out from the first cache directory and the identity of the processor using the data. Thus by this expedient, only the directory known to be backed by system cached data will be evaluated for system cache memory data.

US Patent:

7577795, Aug 18, 2009

Filed:

Jan 25, 2006

Appl. No.:

11/339196

Inventors:

David S. Hutton - Poughkeepsie NY, US
Kathryn M. Jackson - Poughkeepsie NY, US
Keith N. Langston - Woodstock NY, US
Pak-kin Mak - Poughkeepsie NY, US
Chung-Lung K. Shum - Wappingers Falls NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 12/00

US Classification:

711141, 711118, 711119, 711144, 711146

Abstract:

Portions of data in a processor system are stored in a slower main memory and are transferred to a faster memory comprising a hierarchy of cache structures between one or more processors and the main memory. For a system with shared L2 cache(s) between the processor(s) and the main memory, an individual L1 cache of a processor must first communicate to an associated L2 cache(s), or check with such L2 cache(s), to obtain a copy of a particular line from a given cache location prior to, or upon modification, or appropriation of data at a given cached location. The individual L1 cache further includes provisions for notifying the L2 cache(s) upon determining when the data stored in the particular cache line in the L1 cache has been replaced, and when the particular cache line is disowned by an L1 cache, the L2 cache is updated to change the state of the particular cache line therein from an ownership state of exclusive to a particular identified CPU to an ownership state of exclusive to no CPU, thereby allowing reduction of cross interrogate delays during another processor acquisition of the same cache line.

US Patent:

8131936, Mar 6, 2012

Filed:

Feb 11, 2005

Appl. No.:

11/056809

Inventors:

Keith N. Langston - Woodstock NY, US
Pak-kin Mak - Poughkeepsie NY, US
Bruce A. Wagar - Hopewell Junction NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 12/00

US Classification:

711128, 711141, 711136, 711E12027

Abstract:

A method and apparatus for implementing a combined data/coherency cache for a shared memory multi-processor. The combined data/coherency cache includes a system cache with a number of entries. The method includes building a system cache directory with a number of entries equal to the number of entries of the system cache. The building includes designating a number of sub-entries for each entry which is determined by a number of sub-entries operable for performing system cache coherency functions. The building also includes providing a sub-entry logic designator for each entry, and mapping one of the sub-entries for each entry to the system cache via the sub-entry logic designator.

US Patent:

8131945, Mar 6, 2012

Filed:

May 5, 2009

Appl. No.:

12/435468

Inventors:

David S. Hutton - Poughkeepsie NY, US
Kathryn M. Jackson - Poughkeepsie NY, US
Keith N. Langston - Woodstock NY, US
Pak-kin Mak - Poughkeepsie NY, US
Chung-Lung K. Shum - Wappingers Falls NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 12/00

US Classification:

711141, 711118, 711119, 711122, 711144, 711146

Abstract:

Caching where portions of data are stored in slower main memory and are transferred to faster memory between one or more processors and the main memory. The cache is such that an individual cache system must communicate to other associated cache systems, or check with such cache systems, to determine if they contain a copy of a given cached location prior to or upon modification or appropriation of data at a given cached location. The cache further includes provisions for determining when the data stored in a particular memory location may be replaced.

US Patent:

8131982, Mar 6, 2012

Filed:

Jun 13, 2008

Appl. No.:

12/138789

Inventors:

Philip G. Emma - Danbury CT, US
Allan M. Hartstein - Chappaqua NY, US
Keith N. Langston - Woodstock NY, US
Brian R. Prasky - Wappingers Falls NY, US
Thomas R. Puzak - Ridgefield CT, US
Charles F. Webb - Wappingers Falls NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 9/312

US Classification:

712225, 712240

Abstract:

A method for branch prediction, the method comprising, receiving a load instruction including a first data location in a first memory area, retrieving data including a branch address and a target address from the first data location, and saving the data in a branch prediction memory, or receiving an unload instruction including the first data location in the first memory area, retrieving data including a branch address and a target address from the branch prediction memory, and saving the data in the first data location.

US Patent:

8566529, Oct 22, 2013

Filed:

Feb 13, 2008

Appl. No.:

12/030501

Inventors:

David S. Hutton - Tallahassee FL, US
Keith N. Langston - Woodstock NY, US
Kathryn M. Jackson - Poughkeepsie NY, US
Hanno Ulrich - Tuebingen, DE
Craig R. Walters - Highland NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 12/00
G06F 13/00
G06F 13/28
G06F 9/44
G06F 13/10
G06F 13/12

US Classification:

711136, 703 21

Abstract:

The exemplary embodiment of the present invention relates to a generalized LRU algorithm is provided that is associated with a specified cache associativity line set value that is determined by a system user. As configured, the LRU algorithm as presented can comprise n-levels for an LRU tree, each specified tree being individually analyzed within the LRU algorithm. Within each LRU tree level comprises the associativity line value can be further broken down into sub-analysis groups of any desired configuration, however, the total sub-analysis group configuration must equal the specified cache associativity line value.

US Patent:

20070180193, Aug 2, 2007

Filed:

Jan 30, 2006

Appl. No.:

11/342993

Inventors:

David Hutton - Poughkeepsie NY, US
Kathryn Jackson - Poughkeepsie NY, US
Keith Langston - Woodstock NY, US
Pak-kin Mak - Poughkeepsie NY, US
Arthur O'Neill - Wappingers Falls NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 12/00

US Classification:

711122000

Abstract:

Using local change bit to direct the install state of the data line. A multi-processor system that having a plurality of individual processors where each of the processors has an associated L1 cache, and the multi-processor system has at least one shared main memory, and at least one shared L2 cache. The method described herein involves writing a data line into an L2 cache comprising and a local change bit to direct the install state of the data line.

US Patent:

20100287358, Nov 11, 2010

Filed:

May 5, 2009

Appl. No.:

12/435631

Inventors:

Philip G. Emma - Danbury CT, US
Allan M. Hartstein - Chappaqua NY, US
Keith N. Langston - Woodstock NY, US
Brian R. Prasky - Wappingers Falls NY, US
Thomas R. Puzak - Ridgefield CT, US
Charles F. Webb - Wappingers Falls NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 9/38
G06F 9/30

US Classification:

712208, 712239, 712E0906, 712E09016

Abstract:

A method for branch prediction, the method comprising, receiving a branch wrong guess instruction having a branch wrong guess instruction address and data including an opcode and a branch target address, determining whether the branch wrong guess instruction was predicted by a branch prediction mechanism, sending the branch wrong guess instruction to an execution unit responsive to determining that the branch wrong guess instruction was predicted by the branch prediction mechanism, and receiving and decoding instructions at the branch target address.