RONet: Scaling GPU System with Silicon Photonic Chiplet

Modern GPU systems integrate hundreds of SMs on a single die, and future scaling envisions even more SMs being incorporated. However, the limited number of transistors per die constrains this growth. While current chiplet technology shows promise, its performance is limited by the bandwidth and energy efficiency of existing chiplet interconnect technologies. In contrast, optical interconnects offer ultra-high bandwidth and energy efficiency, making them ideal for high-performance chiplet-based GPUs. This work proposes a novel region-based optical network, called RONet, that divides a chiplet-based GPU system with a 2D Mesh layout into multiple row and column regions, where each region is connected by a separate optical link. Additionally, RONet employs a tuning-free transmission mechanism to further enhance inter-chiplet bandwidth. Experimental results show that RONet achieves 43% improvement on performance and 25.4% reduction on system energy consumption over the baseline.