A 1.15 TOPS/W, 16-Cores Parallel Ultra-Low Power Cluster with 2b-to-32b Fully Flexible Bit-Precision and Vector Lockstep Execution Mode

IoT end-nodes require extreme performance and energy efficiency coupled with high flexibility to deal with the increasing computational requirements and variety of modern near-sensor data analytics applications. Low-Bitwidth and Mixed-Precision arithmetic is emerging as a trend to address the near-sensor analytics challenge in several fields such as linear algebra, Deep Neural Networks (DNN) inference, and on-line learning. We present Dustin, a fully programmable Multiple Instruction Multiple Data (MIMD) cluster integrating 16 RISC-V cores featuring 2b-to-32b bit-precision instruction set architecture (ISA) extensions enabling fine-grain tunable mixed-precision computation, improving performance and efficiency by 3.7 x and 1.9 x over state-of-the-art fully programmable devices. The cluster can be dynamically configured in Vector Lockstep Execution Mode (VLEM), turning off all IF stages except one, reducing power consumption by up to 38% with no performance degradation. The cluster, implemented in 65nm CMOS technology, achieves a peak performance of 58 GOPS and a peak efficiency of 1.15 TOPS/W.