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:
Mar. 13, 2001
Filed:
Oct. 24, 1997
Stephen Van Doren, Northborough, MA (US);
Simon C. Steely, Jr., Hudson, NH (US);
Madhumitra Sharma, Shrewsbury, MA (US);
Compaq Computer Corporation, Houston, TX (US);
Abstract
A method for preventing inadvertent invalidation of data elements in a system having a separate probe queue and fill queue for each central processing unit, is provided wherein a central processing unit stores a clean data element, that would otherwise have been discarded, in a victim data buffer when it is evicted from cache. The central processing unit subsequently issues a clean-victim command to the system control logic when the readmiss or read-miss-modify command, targeting the data element that maps to the same location in cache as the clean data element, is issued. The clean-victim command causes the duplicate tag store to indicate that the clean data element is no longer stored in that central processing unit's cache. While the data is stored therein, the central processing unit cannot issue a probe message that targets that data until the victim data buffer has been deallocated. The central processing unit cannot modify the data element and therefore, if a probe invalidate has previously been issued for the clean version of the data element, it will not be able to inadvertently invalidate a modified version of the data element.