Benchmarked on HexGrid Cloud : Gemma-4 31B + vLLM + RTX 6000 PRO : 1168 tokens/sec and still asking for more...

#123
by hexgridcloud - opened

We pushed Gemma-4 31B to 24 concurrent requests on a single RTX 6000 PRO Blackwell. The queue never filled. ~1.17k tokens/sec, and it still had headroom.

Most LLM "benchmarks" show you one request at a time. That tells you almost nothing about production.

So we ran Gemma-4 31B (FP8) on vLLM under a real ShareGPT workload, ramping concurrency 12 → 16 → 20 → 24, and watched what actually happens.

The numbers that mattered:

→ Peak throughput: 1,168 tokens/sec total (548 tok/s output)

→ Median time-to-first-token: 0.7s — snappy even under load

→ Queue depth: averaged 0.41, peaked at just 3 while 14–21 requests ran concurrently

→ Server stayed unsaturated across the entire sweep


The one thing to watch:

Tail TTFT
Median first-token stays fast, but p99 climbs to ~19s at the heaviest concurrency. That's the first metric to flex as you push higher — not throughput, not the queue.


Setup:

1× RTX 6000 PRO Blackwell (96GB)
Gemma-4 31B-it, FP8 checkpoint
vLLM 0.20 — prefix caching + chunked prefill on
ShareGPT workload, 1024 max output tokens, streaming ON
Max model length (context) : 4096
Verdict:
A single Blackwell card runs a 31B model at 24-way concurrency without breaking a sweat. The high end-to-end latency is just long generations, not queuing — and there's clearly room to climb past 24.


Token Throughput chart:

image

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E2E Latency

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Full writeup — configs, charts, and per-concurrency breakdown — https://blog.hexgrid.cloud/gemma-4-31b-vllm-on-rtx-6000-pro-1-17k-tokens-sec-and-still-asking-for-more

Any opinions, comments and criticism is invited on this.

Thanks,

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