U.S. patents available from 1976 to present.
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Coherence control by data invalidation in selected processor caches without broadcasting to processor caches not having the data

Patent 5265232 Issued on November 23, 1993. Estimated Expiration Date: Icon_subject April 3, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Inventors

Assignee

Application

No. 679900 filed on 04/03/1991

US Classes:

711/124Cross-interrogating

Examiners

Primary: Robertson, David L.

Attorney, Agent or Firm

International Class

G06F 013/00

Abstract

A coherence directory and its methods of operation are disclosed for private processor caches in a multiple processor system to control data coherence in the system. It provides cross-invalidate (XI) controls for the assignment of exclusive and public ownership to data units in the processor caches, including required cross-invalidation of data units among the processor caches to obtain data coherence in the system in an efficient manner. The coherence directory can be used in a multiple processor system with or without any shared second level (L2) cache, shared or private. When a shared L2 cache is used to improve system access time, the coherence directory can also be used as the second level directory for the shared L2 cache and eliminate the need for any additional L2 directory(s).

Other References

  • Censier et al., "A New Solution to Coherence Problems in Multicache Systems", IEEE Transactions on Computers, C-27 No. 12, Dec. 1978, pp. 1112-1118
  • Chaiken et al., "Directory-Based Cache Coherence in Large-Scale Multiprocessors", Computer, vol. 23, No. 6, Jun., 1990, pp. 49-5
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