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. 27, 1999
Filed:
Sep. 27, 1996
Hewlett-Packard Co., Palo Alto, CA (US);
Abstract
A method and system of maintaining strong ordering in a multiprocessor computer system having a coherent memory. Memory transactions are send from one or more processors to a processor agent. The processor agent sends the transactions to a memory agent via a crossbar switch. The memory agent performs memory coherency operations and sends memory transactions back to the processor agents via the crossbar switch. The crossbar switch, however, may alter the order in which the memory transactions are forwarded to the processor agent. Therefore, the memory agent also sends a timestamp for each memory transaction directly to the processor agent via a dedicated link. An arbitrator within the processor agent receives the timestamps and the memory transactions. Using the timestamps, the arbitrator reorders the memory transactions and sends the transactions to the processors in the order in which the transactions were sent. In addition, the memory agent sends a parity signal with each timestamp. Specific combinations of parity signals and timestamps tell the arbitrator the type of transaction it will receive from the memory agent. Dependent upon the type of transaction, the arbitrator can change the order in which the transactions are sent to the processors.