Pipestitch: An energy-minimal dataflow architecture with lightweight threads

Computing at the extreme edge allows systems with high-resolution sensors to be pushed well outside the reach of traditional communication and power delivery, requiring high-performance, highenergy-efficiency architectures to run complex ML, DSP, image processing, etc. Recent work has demonstrated the suitability of CGRAs for energy-minimal computation, but has focused strictly on energy optimization, neglecting performance. Pipestitch is an energy-minimal CGRA architecture that adds lightweight hardware threads to ordered dataflow, exploiting abundant, untapped parallelism in the complex workloads needed to meet the demands of emerging sensing applications. Pipestitch introduces a programming model, control-flow operator, and synchronization network to allow lightweight hardware threads to pipeline on the CGRA fabric. Across 5 important sparse workloads, Pipestitch achieves a 3.49x increase in performance over RipTide, the state-of-the-art, at a cost of a 1.10x increase in area and a 1.05x increase in energy.