GPU-Resident Top-K for Agentic RAG: I Built a CUDA Kernel So My Retrieval Step Would Stop Bouncing Off the GPU

The article discusses how PCIe transfer latency bottlenecks agentic inference in retrieval-augmented generation (RAG) systems. The author built a custom CUDA kernel for GPU-resident top-K vector search, bypassing the CPU to achieve deterministic microsecond tail latencies. This approach optimizes the retrieval step for agentic workflows by keeping operations entirely on the GPU.