A shared-FPU architecture for ultra-low power MPSoCs

Abstract

In this work we propose a shared floating point unit (FPU) architecture for ultra low power (ULP) system on chips operating at near threshold voltage (NTV). Since high-performance FP units (FPUs) are large and complex, but their utilization is relatively low, adding one FPU per each core in a ULP multicore is costly and power hungry. In our approach, we share a few FPUs among all the cores in the system. This increases the utilization of FPUs leading to an energy-efficient design. As a part of our approach, we propose two different FPU allocation techniques: optimal and random. Experimental results demonstrate that compared to a traditional private-FPU approach, our technique in a multicore system with 8 processors and 2 shared FPUs can increase the performance/(area*power) by 5x for applications with 10% FP operations and by 2.5x for applications with 25% FP operations.