Exploiting locality to improve leakage reduction in embedded drowsy I-caches at same area/speed

In this paper, a technique to reduce the leakage power consumption in embedded drowsy instruction caches (I caches) is proposed. The technique is called “Improved Drowsy” (ID), and adopts a more efficient strategy than standard Drowsy Caches (DCs) to turn off unused cache lines, based on locality. The implementation of ID caches requires minor changes, and the area/speed overhead associated with the additional circuitry is insignificant. The proposed technique is assessed through circuit and cycle accurate simulations on an L1 instruction cache embedded in an ARM XScale processor based system in a 65 nm CMOS technology. Results show that this technique is able to reduce the leakage power by 69% on average. Leakage of DC is shown to be significantly lowered with the proposed ID approach, being DC leakage greater than that of ID by up to 53%, and 10 15% typically.