System-level mitigation of WID leakage power variability using body-bias islands

Abstract

Adaptive Body Biasing (ABB) is a popularly used technique to mitigate the increasing impact of manufacturing process variations on leakage power dissipation. The efficacy of the ABB technique can be improved by partitioning a design into a number of "body-bias islands," each with its individual body-bias voltage. In this paper, we propose a system-level leakage variability mitigation framework to partition a multiprocessor system into body-bias islands at the processing element (PE) granularity at design time, and to optimally assign body-bias voltages to each island post-fabrication. As opposed to prior gate-and circuit-level partitioning techniques that constrain the global clock frequency of the system, we allow each island to run at a different speed and constrain only the relevant system performance metrics -in our case the execution deadlines. Experimental results show the efficacy of the proposed framework in reducing the mean and standard deviation of leakage power dissipation compared to a baseline system without ABB. At the same time, the proposed techniques provide significant runtime improvements over a previously proposed Monte-Carlo based technique while providing similar reductions in leakage power dissipation.

On the Design of Real-Time Systems on Multi-Core Platforms under Uncertainty

“…The more islands that are partitioned, the better improvement that can be achieved. However, the computational complexity also increases exponentially [56,99,57]. In the extreme case, one core forms one island, and this may lead to unacceptable circuitry cost.…”

“…Tschanz et al [159] proposed to apply a single body bias value per die to allow each die to meet the given frequency and power constraints. Garg et al [59,56] also proposed a system-level variability mitigation framework by applying ABB technique. They partitioned a multi-core platform into body-bias islands and assigned body-bias voltages for each island post-fabrication.…”