vLLM v0.33.0 Scheduler Fix Boosts DeepSeek DSpark Throughput by 2.47x
·2026.11.09 03:39
Key point
Removing unnecessary draft-token reservations allows larger prefill chunks and more efficient CUDA graph execution, raising output throughput from 1,373 to 3,390 tok/s.
Details
- vLLM v0.33.0 removes unnecessary draft-token reservations for DSpark and DFlash, separating draft-buffer capacity constraints from the target model's scheduling budget.
- Output throughput for DeepSeek-V4.1-Flash with DSpark (K=5) increased from 1,373 to 3,390 tok/s (+147%) on a single GB300 with TP4.
- Median Time Per Output Token (TPOT) dropped from 29.2 ms to 15.7 ms, and median Time To First Token (TTFT) decreased from 93.6 s to 30.0 s.
- The fix enables larger prefill chunks and reduces mixed prefill/decode iterations, allowing the system to utilize pure-decode CUDA graphs more effectively.
- Observed maximum running requests increased from 52 to 64, while acceptance length remained stable at approximately 4.72 to 4.73.
- Results are specific to the DeepSeek-V4.1-Flash DSpark benchmark configuration and do not establish a universal speedup; DFlash was not benchmarked end-to-end in this change.
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