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:
Sep. 30, 2003
Filed:
Jun. 29, 1998
Brent A. Kingsbury, Beaverton, OR (US);
Jean-Marie Christian Sulmont, Portland, OR (US);
Paul E. McKenney, Beaverton, OR (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A lock-free mechanism is provided for successfully passing messages between processes even if a process is preempted while sending or receiving a message. Messages are communicated between processes using a mailbox data structure stored in memory shared by the processes, without the use of locks or other mutual exclusion entities that would otherwise limit concurrent delivery and receipt of messages placed in the data structure. The data structure in the illustrative embodiment includes one or more message slots for storing messages placed in the data structure and a number of state variables for inserting messages into and removing messages from the message slots. A process sends or retrieves messages by manipulating the state variables using indivisible atomic operations. This ensures that a process cannot be preempted from message passing until it finishes executing the atomic instruction. The method and mechanism have particular value in distributed shared memory (DSM) and non-uniform memory access (NUMA) machines.