A Photonic-CXL Memory Appliance for Scalable KV Cache Management in LLM Inference

The paper addresses the memory wall in LLM inference, where KV cache demands tens of terabytes at hundreds of GB/s exceed current memory tier capabilities. The proposed Marvell Photonic Fabric Memory Appliance replaces electrical switches with a passive fiber shuffle in a switch-free full-crossbar topology, delivering 32 TB shared memory across 16 hosts via photonic-CXL hybrid architecture. Emulation results show over 50% latency reduction versus electrical CXL pools, while simulation demonstrates a 6.6x improvement in time-to-first-token by eliminating cache eviction cliffs for multi-turn workloads. This work matters because it enables practical TB-scale shared memory for concurrent long-context users, overcoming the scalability limits of electrical CXL pooling in real deployments.