Patents Represented by Attorney Diana R. Gerhardt
  • Patent number: 7490200
    Abstract: A cache memory logically partitions a cache array having a single access/command port into at least two slices, and uses a first cache directory to access the first cache array slice while using a second cache directory to access the second cache array slice, but accesses from the cache directories are managed using a single cache arbiter which controls the single access/command port. In the illustrative embodiment, each cache directory has its own directory arbiter to handle conflicting internal requests, and the directory arbiters communicate with the cache arbiter. An address tag associated with a load request is transmitted from the processor core with a designated bit that associates the address tag with only one of the cache array slices whose corresponding directory determines whether the address tag matches a currently valid cache entry.
    Type: Grant
    Filed: February 10, 2005
    Date of Patent: February 10, 2009
    Assignee: International Business Machines Corporation
    Inventors: Leo James Clark, James Stephen Fields, Jr., Guy Lynn Guthrie, William John Starke
  • Patent number: 7469318
    Abstract: A cache memory which loads two memory values into two cache lines by receiving separate portions of a first requested memory value from a first data bus over a first time span of successive clock cycles and receiving separate portions of a second requested memory value from a second data bus over a second time span of successive clock cycles which overlaps with the first time span. In the illustrative embodiment a first input line is used for loading both a first byte array of the first cache line and a first byte array of the second cache line, a second input line is used for loading both a second byte array of the first cache line and a second byte array of the second cache line, and the transmission of the separate portions of the first and second memory values is interleaved between the first and second data busses. The first data bus can be one of a plurality of data busses in a first data bus set, and the second data bus can be one of a plurality of data busses in a second data bus set.
    Type: Grant
    Filed: February 10, 2005
    Date of Patent: December 23, 2008
    Assignee: International Business Machines Corporation
    Inventors: Vicente Enrique Chung, Guy Lynn Guthrie, William John Starke, Jeffrey Adam Stuecheli
  • Patent number: 7386678
    Abstract: An efficient system for bootstrap loading scans cache lines into a cache store queue during a scan phase, and then transmits the cache lines from the cache store queue to a cache memory array during a functional phase. Scan circuitry stores a given cache line in a set of latches associated with one of a plurality of cache entries in the cache store queue, and passes the cache line from the latch set to the associated cache entry. The cache lines may be scanned from test software that is external to the computer system. Read/claim dispatch logic dispatches store instructions for the cache entries to read/claim machines which write the cache lines to the cache memory array without obtaining write permission, after the read/claim machines evaluate a mode bit which indicates that cache entries in the cache store queue are scanned cache lines. In the illustrative embodiment the cache memory is an L2 cache.
    Type: Grant
    Filed: June 28, 2005
    Date of Patent: June 10, 2008
    Assignee: International Business Machines Corporation
    Inventors: Guy L. Guthrie, Jeffrey W. Kellington, Kevin F. Reick, Hugh Shen
  • Patent number: 7308537
    Abstract: A cache memory logically partitions a cache array into at least two slices each having a plurality of cache lines, with a given cache line spread across two or more cache ways of contiguous bytes and a given cache way shared between the two cache slices, and if one a cache way is defective that is part of a first cache line in the first cache slice and part of a second cache line in the second cache slice, it is disabled while continuing to use at least one other cache way which is also part of the first cache line and part of the second cache line. In the illustrative embodiment the cache array is set associative and at least two different cache ways for a given cache line contain different congruence classes for that cache line. The defective cache way can be disabled by preventing an eviction mechanism from allocating any congruence class in the defective way. For example, half of the cache line can be disabled (i.e., half of the congruence classes).
    Type: Grant
    Filed: February 10, 2005
    Date of Patent: December 11, 2007
    Assignee: International Business Machines Corporation
    Inventors: James Stephen Fields, Jr., Guy Lynn Guthrie, Kirk Samuel Livingston, William John Starke