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Prefetch Deconfirmation Based on BHT Error

IP.com Disclosure Number: IPCOM000038887D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01

Publishing Venue

IBM

Related People

Authors:
Emma, PG Knight, JW Pomerene, JH Rechtschaffen, RN Sparacio, FJ [+details]

Abstract

This invention improves the performance of confirmed sequential prefetching schemes by using the occurrence of Branch History Table (BHT) errors as an indication of a change in program behavior. Sequential prefetching relies on sequential behavior of programs and any additional sequentiality of instruction (I) fetching introduced by machine organization. It is of interest to note that the sequentiality introduced by machine organization is also historically repetitious for some machine organizations but not for others. BHT driven I-fetching is an example of the latter, and as such the dynamic action of a BHT and the methods used to confirm prefetching can be antagonistic in some cases.