AN ENERGY-EFFICIENT DEMAND-DRIVEN REGISTER FILE FOR MOBILE GPUs

Abstract

In response to the remarkable increase in 3D applications in mobile devices in recent years, mobile GPUs have become widely available. Although the computation requirements are tremendous of 3D applications, they are highly data parallel operations. Therefore, mobile GPUs are usually hardware multithreaded to increase their throughput and achieve real-time rendering. This design increases energy consumption by duplicate register files in shaders. However, the register usage of shading programs is often relatively low, which causes many duplicated registers to go unused, and thus wastes energy. In addition, long latency memory operations can consume unnecessary energy to activate registers as well. This study proposes a compiler-assisted energy-efficient demand-driven register file (EDRF) to reduce energy consumptions of registers that are unused and waiting for long latency memory operations. The proposed EDRF is shared on demand between concurrent threads with multiple power gating modes. The management scheme of EDRF puts registers into different power modes to save leakage energy. In addition, the partitioned structure of EDRF saves dynamic energy for accessing registers. Results show that the average dynamic and leakage energy reduction ratios are 84.18% and 99.20%, respectively. Furthermore, the performance degradation from the proposed EDRF is only 0.50% on average.