Aggressive superpage support with the shadow memory and the partial-subblock TLB

摘要

While superpages are an efficient solution to increase TLB reach, strong requirements for using superpages hinder the actual utilization. Two previous solutions, the partial-subblock TLB and the shadow memory were proposed to release the requirements. The partial-subblock TLB releases only a small portion of the requirements. The shadow memory releases most of the requirements but introduces other serious problems. We propose a hybrid scheme which integrates both the shadow memory and the partial-subblock TLB, thereby enjoying the benefits inherited from both sides. The hybrid scheme has as high a superpage utilization as the shadow memory, and avoids most of the problems in the shadow memory by virtue of the partial-subblock TLB. The experiment shows that the hybrid scheme outperforms the previous schemes though its hardware cost and overhead are considered.