vLLM added bidirectional and push-based KV cache transfer for disaggregated prefill/decode inference to reduce time-to-first-token
Feature update Provisional 84% confidence first seen
Two AWS Machine Learning articles report that vLLM introduced new mechanisms for disaggregated serving, including bidirectional KV cache transfer and a push-based KV transfer connector (via NVIDIA Inference Xfer Library) between prefill and decode components. In EC2 P5en 1P1D tests with EFA, the changes reduced TTFT and improved TPOT metrics for models such as Qwen3-32B and others, with results varying by prompt length and transfer mode.