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:
Nov. 09, 1999
Filed:
Mar. 25, 1997
Hitachi, Ltd., Tokyo, JP;
Abstract
When the OS judges that a read request to the secondary storage device from the user process is the sequential access, the OS judges whether prefetching is to be stopped before the data succeeding to the data designated by the request is prefetched, so as to decrease replacement of data prefetched to the main memory by other data before the data is used. The judgment is executed to prevent that succeeding data from being replaced by other data after the succeeding data is prefetched to the cache area in the main memory. That is, it is judged whether the data requested by the read request has already been prefetched, and has already been replaced by other data before the requested data is used by the user process, if the requested data has been prefetched. When these two conditions are met, prefetch is useless. The prefetching accompanying this read request is not executed, the prefetch stop flag is set, and prefetching is prohibited to the succeeding sequential access by this prefetch stop flag. The technology is also disclosed which controls allocation of the cache entries so that a cache entry which holds prefetched data is not used to hold other data before the data is used.