PICNIC: Silicon Photonic Interconnected Chiplets with Computational Network and In-memory Computing for LLM Inference Acceleration

Abstract: This paper presents a 3D-stacked chiplets based LLM inference accelerator, consisting of non-volatile in-memory-computing processing elements (PEs) and Inter-PE Computational Network (IPCN), interconnected via silicon photonic to effectively address the communication bottlenecks. A LLM mapping scheme was developed to optimize hardware scheduling and workload mapping. Simulation results show it achieves $3.95\times$ speedup and $30\times$ efficiency improvement over the Nvidia A100 before chiplet clustering and power gating scheme (CCPG). Additionally, the system achieves further scalability and efficiency improvement with the implementation of CCPG to accommodate larger models, attaining $57\times$ efficiency improvement over Nvidia H100 at similar throughput.