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:
Jun. 02, 1998
Filed:
Jan. 29, 1997
Sanjay Vishin, Sunnyvale, CA (US);
Joseph A Petolino, Jr, Palo Alto, CA (US);
Sun Microsystems, Inc., Mountain View, CA (US);
Abstract
Methods and apparatus for using a store allocate policy to eliminate the stale data problem in a direct mapped, write-through virtual data cache. A hardware mechanism provided by the present invention, ensures that a single cache location associated with more than one virtual address does not become stale with respect to the main memory. By using a store allocate policy along with a write-through virtual cache, each time a store miss occurs, the data cache location for which the store miss occurred will be updated with new data brought back from the main memory along with a new cache tag. The store allocate policy for a write-through virtual data cache is implemented by a data cache controller. Thus, using this cache policy, the cache is updated along with the main memory even after a store miss. Furthermore, since not more than one virtual address may exist at any one time in the cache, it is ensured that a virtual address that is found in the cache will always contain the most updated data, hence overcoming the stale data problem.