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:
Jan. 03, 2023
Filed:
May. 10, 2021
Apple Inc., Cupertino, CA (US);
James Vash, San Ramon, CA (US);
Gaurav Garg, San Jose, CA (US);
Brian P. Lilly, San Francisco, CA (US);
Ramesh B. Gunna, San Jose, CA (US);
Steven R. Hutsell, San Jose, CA (US);
Lital Levy-Rubin, Tel Aviv, IL;
Per H. Hammarlund, Sunnyvale, CA (US);
Harshavardhan Kaushikkar, Santa Clara, CA (US);
Apple Inc., Cupertino, CA (US);
Abstract
A scalable cache coherency protocol for system including a plurality of coherent agents coupled to one or more memory controllers is described. The memory controller may implement a precise directory for cache blocks from the memory to which the memory controller is coupled. Multiple requests to a cache block may be outstanding, and snoops and completions for requests may include an expected cache state at the receiving agent, as indicated by a directory in the memory controller when the request was processed, to allow the receiving agent to detect race conditions. In an embodiment, the cache states may include a primary shared and a secondary shared state. The primary shared state may apply to a coherent agent that bears responsibility for transmitting a copy of the cache block to a requesting agent. In an embodiment, at least two types of snoops may be supported: snoop forward and snoop back.