The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 01, 2008
Filed:
Jul. 19, 2005
Jason Frederick Cantin, Madison, WI (US);
Steven R. Kunkel, Rochester, MN (US);
Jason Frederick Cantin, Madison, WI (US);
Steven R. Kunkel, Rochester, MN (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method, apparatus, and computer program product are disclosed for reducing the number of unnecessarily broadcast local requests to reduce the latency to access data from remote nodes in an SMP computer system. A shared invalid cache coherency protocol state is declined that predicts whether a memory read request to read data in a shared cache line can be satisfied within a local node. When a cache line is in the shared invalid state, a valid copy of the data is predicted to be located in the local node. When a cache line is in the invalid state and not in the shared invalid state, a valid copy of the data is predicted to be located in one of the remote nodes. Memory read requests to read data in a cache line that is not currently in tile shared invalid state are broadcast first to remote nodes. Memory read requests to read data in a cache line that is currently in the shared invalid state are broadcast first to a local node, and in response to being unable to satisfy the memory read requests within the local node, the memory read requests are broadcast to the remote nodes.