International Business Machines Corporation

Kevin C Stelzer

Jonathan James DeMent

Ronald P Hall

Thuong Quang Truong

Wen-Tzer Thomas Chen, Jr

Peichun Peter Liu

Alvan Wing Ng

Roy Moonseuk Kim

Brian Patrick Hanley

A system and method for reducing store latency in symmetrical multiprocessor systems are provided. Bus agents are provided which monitor reflected ownership requests (Dclaims) to determine if the reflected Dclaim is its own Dclaim. If so, the bus agent determines that it is the winner of the ownership request and can immediately perform data modification using its associated local cache. If the bus agent determines that the reflected Dclaim does not match its own Dclaim, it determines that it is the loser of the ownership request and invalidates the corresponding cache line in its own local cache. The loser bus agent may then send a Read With Intent to Modify request to obtain the data from another cache and place it into its own cache for modification. These operations are performed without the need for a Kill request and without having to perform retries of a losing ownership request.

System and method for reducing store latency in symmetrical multiprocessor systems

A computer implemented method and system for managing replacement of sets in a locked cache. A cache access by a program is performed, and a side of a binary tree pointed to by a base leaf is identified. A determination is made as to whether a number of accesses to the identified side of the binary tree equals a number of sets associated with the program on the identified side. The base leaf is changed to point to an opposite side of the binary tree if the number of accesses to the identified side equals the number of sets associated with the program on the identified side.

Pseudo-LRU virtual counter for a locking cache

The present invention provides for a plurality of partitioned ways of an associative cache. A pseudo-least recently used binary tree is provided, as is a way partition binary tree, and signals are derived from the way partition binary tree as a function of a mapped partition. Signals from the way partition binary tree and the pseudo-least recently used binary tree are combined. A cache line replacement signal is employable to select one way of a partition as a function of the pseudo-least recently used binary tree and the signals derived from the way partition binary tree.

Implementation of a pseudo-LRU algorithm in a partitioned cache

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Austin, TX, United States of America

Kevin C Stelzer