Power Optimizations for Transport Triggered SIMD Processors

Abstract

Power consumption in modern processor design is a key aspect. Optimizing the processor for power leads to direct savings in battery energy consumption in case of mobile devices. At the same time, many mobile applications demand high computational performance. In case of large scale computing, low power compute devices help in thermal design and in reducing the electricity bill. This paper presents a case study of a customized low power vector processor design that was synthesized on a 28 nm process technology. The processor has a programmer exposed datapath based on the transport triggered architecture programming model. The paper’s focus is on the RTL and microarchitecture level power optimizations applied to the design. Using register file datapath gating, register file banking and enabling clock gating of individual pipeline stages in pipelined function units, up to one fourth of power and energy savings could be achieved with only a small area overhead. On top of this, for the measured radio applications, the exposed datapath architecture helped to achieve major power improvements in comparison to the traditional VLIW programming model by utilizing optimizations unique to transport triggered architectures.