Speed test matrix
Qwen3.5-27B on H200 NVL 141GB
vllm · 0.26.1rc1.dev638+g52be12cfa · BF166 contexts (8K–251K) × 8 concurrency levels (1–128) · prefill at 8K, 16K, 32K, 64K, 128K, 251K, 256K
Hardware
- Type
- Discrete GPU
- GPU
- H200 NVL
- VRAM
- 141 GB
- OS
- linux
Engine
- Engine
- vllm
- Version
- 0.26.1rc1.dev638+g52be12cfa
- Quantization
- BF16
- Backend
- cuda
- Repository
- github.com/vllm-project/vllm
- Build
- cuda-13.2
- Commit
52be12cfac0c
Run
- Served model
- qwen
- Revision
- main
- Benchmark tool
- llm-inference-bench v0.4.29
- Decode test
- Fixed duration
- Prefill mode
- Measured during decode warm-up
- Time per measurement
- 30 s
- Max output
- 4,096 tokens
Launch command
"$HOME/env_h200-qwen-vllm/bin/vllm" serve Qwen/Qwen3.5-27B --served-model-name qwen --trust-remote-code --tensor-parallel-size 1 --reasoning-parser qwen3 --enable-auto-tool-choice --tool-call-parser qwen3_coder --max-model-len 262144 --gpu-memory-utilization 0.883421 --host 0.0.0.0 --port 8000 --api-key <redacted>
Prefill
prompt tok/s by context length8K context10.4K790 ms TTFT
16K context10.1K1,600 ms TTFT
32K context9,6403,350 ms TTFT
64K context8,8937,244 ms TTFT
128K context7,44417,288 ms TTFT
251K context5,67044,482 ms TTFT
256K context5,64345,579 ms TTFT
Sustained decode
total tok/s · rows are context length, columns are simultaneous requests| Context | 1 | 2 | 4 | 8 | 16 | 32 | 64 | 128 |
|---|---|---|---|---|---|---|---|---|
| 8K | 59.376 ms TTFT | 117.5135 ms TTFT | 228.21,825 ms TTFT | 430.6339 ms TTFT | 790.2632 ms TTFT | 1,371.11,276 ms TTFT | 2,071.02,406 ms TTFT | Over capacity |
| 16K | 58.9127 ms TTFT | 116.1165 ms TTFT | 223.2317 ms TTFT | 413.0493 ms TTFT | 734.7931 ms TTFT | 1,204.01,790 ms TTFT | Over capacity | Over capacity |
| 32K | 58.1121 ms TTFT | 113.1185 ms TTFT | 213.3256 ms TTFT | 382.4343 ms TTFT | 642.3482 ms TTFT | Over capacity | Over capacity | Over capacity |
| 64K | 56.4144 ms TTFT | 107.6252 ms TTFT | 196.7380 ms TTFT | 331.6516 ms TTFT | Over capacity | Over capacity | Over capacity | Over capacity |
| 128K | 53.4282 ms TTFT | 98.1401 ms TTFT | 168.5583 ms TTFT | 256.2936 ms TTFT | Over capacity | Over capacity | Over capacity | Over capacity |
| 251K | 48.4653 ms TTFT | 83.2890 ms TTFT | 129.41,274 ms TTFT | Over capacity | Over capacity | Over capacity | Over capacity | Over capacity |
Over capacity: not run because this many requests at this context would exceed the server's KV cache.
TTFT is measured after the benchmark warms the server's prompt cache, so it mostly excludes prefill.
All measurements
Latencies are medians. Total tok/s is output across all simultaneous requests.| Phase | Context | Requests at once | Status | Total tok/s | Per request tok/s | TTFT | Time between tokens | Average active requests | Completed requests | Output tokens | Measured for |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Prefill | 8K | 1 | Valid | 10.4K | — | 790 ms | — | — | 1 | — | — |
| Prefill | 16K | 1 | Valid | 10.1K | — | 1,600 ms | — | — | 1 | — | — |
| Prefill | 32K | 1 | Valid | 9,640.0 | — | 3,350 ms | — | — | 1 | — | — |
| Prefill | 64K | 1 | Valid | 8,893.0 | — | 7,244 ms | — | — | 1 | — | — |
| Prefill | 128K | 1 | Valid | 7,444.0 | — | 17,288 ms | — | — | 1 | — | — |
| Prefill | 251K | 1 | Valid | 5,670.0 | — | 44,482 ms | — | — | 1 | — | — |
| Prefill | 256K | 1 | Valid | 5,643.0 | — | 45,579 ms | — | — | 1 | — | — |
| Sustained decode | 8K | 1 | Valid | 59.3 | 59.3 | 76 ms | 16.9 ms | 1.0 | 0 | 1,779 | 30.0 s |
| Sustained decode | 8K | 2 | Valid | 117.5 | 58.8 | 135 ms | 17.0 ms | 2.0 | 0 | 3,524 | 30.0 s |
| Sustained decode | 8K | 4 | Valid | 228.2 | 57.1 | 1,825 ms | 17.5 ms | 4.0 | 0 | 6,844 | 30.0 s |
| Sustained decode | 8K | 8 | Valid | 430.6 | 53.8 | 339 ms | 18.6 ms | 8.0 | 0 | 12,912 | 30.0 s |
| Sustained decode | 8K | 16 | Valid | 790.2 | 49.4 | 632 ms | 20.2 ms | 16.0 | 0 | 23,696 | 30.0 s |
| Sustained decode | 8K | 32 | Valid | 1,371.1 | 43.0 | 1,276 ms | 23.2 ms | 32.0 | 0 | 41,120 | 30.0 s |
| Sustained decode | 8K | 64 | Valid | 2,071.0 | 32.5 | 2,406 ms | 30.8 ms | 64.0 | 0 | 62,144 | 30.0 s |
| Sustained decode | 8K | 128 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 16K | 1 | Valid | 58.9 | 58.9 | 127 ms | 17.0 ms | 1.0 | 0 | 1,768 | 30.0 s |
| Sustained decode | 16K | 2 | Valid | 116.1 | 58.0 | 165 ms | 17.2 ms | 2.0 | 0 | 3,484 | 30.0 s |
| Sustained decode | 16K | 4 | Valid | 223.2 | 55.9 | 317 ms | 17.9 ms | 4.0 | 0 | 6,692 | 30.0 s |
| Sustained decode | 16K | 8 | Valid | 413.0 | 51.6 | 493 ms | 19.4 ms | 8.0 | 0 | 12,384 | 30.0 s |
| Sustained decode | 16K | 16 | Valid | 734.7 | 45.9 | 931 ms | 21.8 ms | 16.0 | 0 | 22,032 | 30.0 s |
| Sustained decode | 16K | 32 | Valid | 1,204.0 | 37.6 | 1,790 ms | 26.6 ms | 32.0 | 0 | 36,096 | 30.0 s |
| Sustained decode | 16K | 64 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 16K | 128 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 32K | 1 | Valid | 58.1 | 58.1 | 121 ms | 17.2 ms | 1.0 | 0 | 1,743 | 30.0 s |
| Sustained decode | 32K | 2 | Valid | 113.1 | 56.6 | 185 ms | 17.7 ms | 2.0 | 0 | 3,394 | 30.0 s |
| Sustained decode | 32K | 4 | Valid | 213.3 | 53.4 | 256 ms | 18.7 ms | 4.0 | 0 | 6,400 | 30.0 s |
| Sustained decode | 32K | 8 | Valid | 382.4 | 47.8 | 343 ms | 20.9 ms | 8.0 | 0 | 11,472 | 30.0 s |
| Sustained decode | 32K | 16 | Valid | 642.3 | 40.1 | 482 ms | 24.9 ms | 16.0 | 0 | 19,280 | 30.0 s |
| Sustained decode | 32K | 32 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 32K | 64 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 32K | 128 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 64K | 1 | Valid | 56.4 | 56.4 | 144 ms | 17.7 ms | 1.0 | 0 | 1,691 | 30.0 s |
| Sustained decode | 64K | 2 | Valid | 107.6 | 53.9 | 252 ms | 18.6 ms | 2.0 | 0 | 3,228 | 30.0 s |
| Sustained decode | 64K | 4 | Valid | 196.7 | 49.2 | 380 ms | 20.3 ms | 4.0 | 0 | 5,900 | 30.0 s |
| Sustained decode | 64K | 8 | Valid | 331.6 | 41.4 | 516 ms | 24.1 ms | 8.0 | 0 | 9,952 | 30.0 s |
| Sustained decode | 64K | 16 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 64K | 32 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 64K | 64 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 64K | 128 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 128K | 1 | Valid | 53.4 | 53.5 | 282 ms | 18.7 ms | 1.0 | 0 | 1,602 | 30.0 s |
| Sustained decode | 128K | 2 | Valid | 98.1 | 49.1 | 401 ms | 20.4 ms | 2.0 | 0 | 2,944 | 30.0 s |
| Sustained decode | 128K | 4 | Valid | 168.5 | 42.2 | 583 ms | 23.7 ms | 4.0 | 0 | 5,052 | 30.0 s |
| Sustained decode | 128K | 8 | Valid | 256.2 | 32.1 | 936 ms | 31.2 ms | 8.0 | 0 | 7,688 | 30.0 s |
| Sustained decode | 128K | 16 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 128K | 32 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 128K | 64 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 128K | 128 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 251K | 1 | Valid | 48.4 | 48.5 | 653 ms | 20.6 ms | 1.0 | 0 | 1,452 | 30.0 s |
| Sustained decode | 251K | 2 | Valid | 83.2 | 41.6 | 890 ms | 24.0 ms | 2.0 | 0 | 2,496 | 30.0 s |
| Sustained decode | 251K | 4 | Valid | 129.4 | 32.3 | 1,274 ms | 31.0 ms | 4.0 | 0 | 3,880 | 30.0 s |
| Sustained decode | 251K | 8 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 251K | 16 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 251K | 32 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 251K | 64 | Over capacity | — | — | — | — | — | — | — | — |
| Sustained decode | 251K | 128 | Over capacity | — | — | — | — | — | — | — | — |
Over capacity: not run because this many requests at this context would exceed the server's KV cache.