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:
Feb. 04, 2003
Filed:
Sep. 15, 2000
James E. McCormick, Jr., Fort Collins, CO (US);
Stephen R. Undy, Fort Collins, CO (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
In a cache which writes new data over less recently used data, methods and apparatus which dispense with the convention of marking new cache data as most recently used. Instead, non-referenced data is marked as less recently used when it is written into a cache, and referenced data is marked as more recently used when it is written into a cache. Referenced data may correspond to fetch data, and non-referenced data may correspond to prefetch data. Upon fetch of a data value from the cache, its use status may be updated to more recently used. The methods and apparatus have the affect of preserving (n−1)/n of a cache's entries for the storage of fetch data, while limiting the storage of prefetch data to 1/n of a cache's entries. Pollution which results from unneeded prefetch data is therefore limited to 1/n of the cache. In reality, however, pollution from unneeded prefetch data will be significantly less, as many prefetch data values will ultimately be fetched prior to their overwrite with new data, and upon their fetch, their use status can be upgraded to most recently used, thus ensuring their continued maintenance in the cache.