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Reader set encoding for directory of shared cache memory in multiprocessor system

United States Patent

June 10, 2014
View the Complete Patent at the US Patent & Trademark Office
In a parallel processing system with speculative execution, conflict checking occurs in a directory lookup of a cache memory that is shared by all processors. In each case, the same physical memory address will map to the same set of that cache, no matter which processor originated that access. The directory includes a dynamic reader set encoding, indicating what speculative threads have read a particular line. This reader set encoding is used in conflict checking. A bitset encoding is used to specify particular threads that have read the line.
Ahn; Daniel (Yorktown Heights, NY), Ceze; Luis H. (Urbana, IL), Gara; Alan (Mount Kisco, NY), Ohmacht; Martin (Yorktown Heights, NY), Xiaotong; Zhuang (White Plains, NY)
International Business Machines Corporation (Armonk, NY)
13/ 008,583
January 18, 2011
GOVERNMENT CONTRACT This invention was made with Government support under Contract No.: B554331 awarded by Department of Energy. The Government has certain rights in this invention.