Access-mode Predictions for Low-Power Cache Design

Zhichun Zhu and Xiaodong Zhang

IEEE Micro, Vol. 22, No. 2, March/April, 2002, pp. 58-71.


Researchers have proposed different techniques to reduce the power
consumption of set-associative caches.  Way-prediction techniques can
reduce the energy consumption of cache hits, while phased accessing
techniques can reduce the energy consumption of cache misses.  To achieve
minimal energy consumption for both cache hits and misses, we propose an
{\em access mode prediction} technique based on cache hit/miss speculation
for low power cache design.  With access mode predictions (AMP), the cache
accesses can be adaptively switched between the way-prediction and the
phased accessing modes.  Our study shows that the AMP cache can further
reduce energy consumption and energy-delay product compared with both
way-prediction and phased caches.  We have also looked into alternate
way-prediction schemes that support the AMP cache.  We conclude that
a power-efficient variant of the way-prediction method based on the
multicolumn cache idea performs best.