Electrical computers and digital processing systems: processing – Processing control – Branching
Reexamination Certificate
2002-07-18
2009-02-17
Chan, Eddie P (Department: 2183)
Electrical computers and digital processing systems: processing
Processing control
Branching
Reexamination Certificate
active
07493480
ABSTRACT:
A two level branch history table (TLBHT) is substantially improved by providing a mechanism to prefetch entries from the very large second level branch history table (L2 BHT) into the active (very fast) first level branch history table (L1 BHT) before the processor uses them in the branch prediction process and at the same time prefetch cache misses into the instruction cache. The mechanism prefetches entries from the very large L2 BHT into the very fast L1 BHT before the processor uses them in the branch prediction process. A TLBHT is successful because it can prefetch branch entries into the L1 BHT sufficiently ahead of the time the entry is needed. This feature of the TLBHT is also used to prefetch instructions into the cache ahead of their use. In fact, the timeliness of the prefetches produced by the TLBHT can be used to remove most of the cycle time penalty incurred by cache misses.
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Emma Philip G.
Getzlaff Klaus J.
Hartstein Allan M.
Pflueger Thomas
Puzak Thomas R.
Chan Eddie P
F. Chau & Associates LLC
International Business Machines - Corporation
Petranek Jacob
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