vLLM guide explains disaggregated serving for prefill and decode
Original titleTaking vLLM Apart: A Practical Guide to Disaggregated Serving
AISummary
The vLLM blog guide explains how separating prefill and decode, and moving tokenization to a CPU-only render tier, can keep token streams from stalling under load.
In a two-L40S test on Qwen2.5-7B, collocated p99 inter-token latency reached 169 ms at 0.4 req/s while disaggregated serving stayed between 25 and 52 ms.
The guide notes that the gain depends on fast KV cache transfer, and it includes setup code for NIXL-based serving and the render/derender API.
Source: vLLM Blog · vllm.aiPublished · added here