The Fabric Is the Cluster Driver: Cross-Layer eBPF Policies for GPU-CXL Fabrics
fabric_ext introduces a cross-layer eBPF middleware compiler and runtime for enforcing extensible OS policies across GPU-CXL fabrics. The method uses a semantic movement graph abstraction that describes data movement characteristics and is compiled into per-device eBPF programs, BPF maps, and runtime artifacts for bpftime and dputime. Experimental evidence from the LLM prefill stress case shows that fabric_ext can manage attention and FFN dataflows crossing GPU tensor execution, DPU/NIC event execution, and CXL switch-local islands. This matters because it enables unified, data-driven policy enforcement across heterogeneous fabric components, improving observability and control in disaggregated memory systems.