A New Virtual-Address-Mapping Mechanism for Low-Energy I-Cache

WPSA (Way-predicting set-associative) cache is a well-known approach to reduce the set-associative I-cache´s energy consumption. However, an extra cycle is needed if a prediction miss occurs. This may actually degrade the performance. This paper proposes a new virtual-address-mapping mechanism to aim at only accessing one way in I-cache within one cycle by adding a virtual address matching table which is implemented parallel to the TLB´s address translating. This approach reduces the energy consumption while maintaining the performance. Simulation-based evaluation shows that in contrast with the conventional set-associative I-cache, the approach we proposed can reduce about 63%~66% energy consumption and improve nearly 10% performance versus way-predicting access. Even though there are still energy costs, the method still saves a lot of energy.