Large Language Model (LLM) services require distributed inference systems that sustain high throughput under limited memory capacity and increasing request concurrency. Ray, a distributed processing framework, enables cluster-level distributed execution, while vLLM improves node-level inference efficiency. This paper presents a Ray–vLLM based distributed inference architecture that directly maps RAG-composed requests to Actor-level execution. We evaluate performances of four configurations with and without vLLM and Ray Serve on both GPU and NPU clusters. The proposed Ray Actor with vLLM structure achieves the best overall performance on both platforms, reducing total latency by 27.7% and increasing throughput by 38.2% on GPU, and reducing total latency by 20.3% while increasing throughput by 25.5% on NPU compared to the Ray Serve-vLLM baseline. The results show that vLLM is the key factor in performance improvements. It improves both request-level latency and throughput in the GPU environment, whereas it mainly enhances batch-level execution efficiency and overall throughput in the NPU environment. The results further show that the Actor-direct execution path enables efficient distributed LLM inference and is well suited for high-throughput RAG-based services.
Keyword
Distributed Inference System, Large Language Model, vLLM, Ray
KSP Keywords
Batch-level, Cluster-level, Distributed Execution, Distributed inference, Execution efficiency, High throughput, Inference System, Key factor, Language Models, Overall performance, distributed processing
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