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

Short summary

PCIe transfers create a silent latency bottleneck in agentic RAG by moving vector data between GPU and CPU on each retrieval step. Building a GPU-resident vector search kernel in CUDA eliminates these transfers, achieving deterministic microsecond-scale tail latencies for faster agentic inference. This implementation keeps the entire retrieval operation on-device, removing the costly transfer overhead that degrades performance.

• •PCIe transfers bottleneck agentic RAG by bouncing vector data between GPU and CPU
• •GPU-resident CUDA kernels achieve microsecond tail latencies by keeping retrieval on-device
• •Eliminates performance degradation from CPU transfer overhead

Generated with AI, which can make mistakes.