# Elastic Expert Parallelism

In vLLM's Elastic Expert Parallelism, resizing a deployment used to stop serving: scaling DeepSeek V4 Pro from 16 to 20 GB200 GPUs paused for 99.62 seconds. The new design splits reconfiguration into background preparation and a short commit, while NIXL EP adds or removes communication ranks in place and keeps captured CUDA graphs valid, cutting the same benchmark's pause to 0.82 seconds on scale-up and 1.96 seconds on scale-down.

In vLLM's Elastic Expert Parallelism, resizing a deployment used to stop serving: scaling DeepSeek V4 Pro from 16 to 20 GB200 GPUs paused for 99.62 seconds. The new design splits reconfiguration into background preparation and a short commit, while NIXL EP adds or removes communication ranks in place and keeps captured CUDA graphs valid, cutting the same benchmark's pause to 0.82 seconds on scale-up and 1.96 seconds on scale-down.