Sub-pJ per operation scalable computing: The PULP experience

Ultra-low power operation and extreme energy efficiency are strong requirements for a number of high-growth Internet of-Things (IoT) applications requiring near-sensor processing. A promising approach to achieve major energy efficiency improvements is near-threshold computing. However, frequency degradation due to aggressive voltage scaling may not be acceptable for performance-constrained applications. The PULP platform leverages multi-core parallelism with explicitly-managed shared L1 memory to overcome performance degradation at low voltage, while maintaining the flexibility and programmability typical of instruction processors. PULP supports OpenMP, OpenCL, and OpenVX parallel programming with hardware support for energy efficient synchronization. Multiple silicon implementations of PULP have been taped out and achieve hundreds of GOPS/W on video, audio, inertial sensor data processing and classification, within power envelopes of a few milliwatts. PULP hardware and software are open-source, with the goal of supporting and boosting an innovation ecosystem focusing on ULP computing for the IoT.