Garbage output

#8
by andylele - opened

Something is wrong with this FP8. I tried both vllm and SGLang and they all output gibberish words and random characters.

My CLI:
SGLang latest docker tag pulled today
SGLANG_ENABLE_SPEC_V2=1 sglang serve --model-path Qwen/Qwen3.6-27B-FP8
--reasoning-parser qwen3
--tool-call-parser qwen3_coder
--speculative-algorithm NEXTN
--speculative-num-steps 3
--speculative-eagle-topk 1
--speculative-num-draft-tokens 4
--mamba-scheduler-strategy extra_buffer
--mem-fraction-static 0.8

vllm version 0.19.1
vllm serve Qwen/Qwen3.6-27B-FP8 --host 0.0.0.0 --port 8000 --served-model-name Qwen3.6-27B-FP8 --uvicorn-log-level error --gpu-memory-utilization 0.9 --tensor-parallel-size 1 --enable-prefix-caching --enable-auto-tool-choice --tool-call-parser qwen3_coder --reasoning-parser qwen3 --max-model-len 131072 --max-num-seqs 1 --max-num-batched-tokens 4096 --kv-cache-dtype fp8 --disable-log-stats --enable-sleep-mode

I'm using H100. Does anyone have the same problem?

0 problems on VLLM v0.19.1;
Try without draft on Sglang;
Try without kv-cache quantization on vllm; I think you have plenty of VRAM so no need for quantization of kvcache.
If you do need more space try
--limit-mm-per-prompt '{"image": 16, "video": 0}'
for vllm; this disables video and limits images to 16 per prompt.

Something is wrong with this FP8. I tried both vllm and SGLang and they all output gibberish words and random characters.

My CLI:
SGLang latest docker tag pulled today
SGLANG_ENABLE_SPEC_V2=1 sglang serve --model-path Qwen/Qwen3.6-27B-FP8
--reasoning-parser qwen3
--tool-call-parser qwen3_coder
--speculative-algorithm NEXTN
--speculative-num-steps 3
--speculative-eagle-topk 1
--speculative-num-draft-tokens 4
--mamba-scheduler-strategy extra_buffer
--mem-fraction-static 0.8

vllm version 0.19.1
vllm serve Qwen/Qwen3.6-27B-FP8 --host 0.0.0.0 --port 8000 --served-model-name Qwen3.6-27B-FP8 --uvicorn-log-level error --gpu-memory-utilization 0.9 --tensor-parallel-size 1 --enable-prefix-caching --enable-auto-tool-choice --tool-call-parser qwen3_coder --reasoning-parser qwen3 --max-model-len 131072 --max-num-seqs 1 --max-num-batched-tokens 4096 --kv-cache-dtype fp8 --disable-log-stats --enable-sleep-mode

I'm using H100. Does anyone have the same problem?

same with rtx pro 6000, vllm is fine

0 problems on VLLM v0.19.1;
Try without draft on Sglang;
Try without kv-cache quantization on vllm; I think you have plenty of VRAM so no need for quantization of kvcache.
If you do need more space try
--limit-mm-per-prompt '{"image": 16, "video": 0}'
for vllm; this disables video and limits images to 16 per prompt.

I tried again this morning with the FP16 version, still has the same problem. For example:

Prompt: "hi"
Output:
i, am a but the boy of app is age running
17
, iHere's have a a thinking very serious process: concern
, i.
am请 a teacher检查 of应用名称 chemistry是否正确 and i, want以及是否 to已 make a启动 web该应用 app。 that请, number i had0 my of0 wisdom times tooth removed2 about in2 my3-24 program2 days
ago and``` icsharp, I am working on a program that I am going to use at my work

My exact CLI:

Apr 24 at 09:22:43.721
vllm serve Qwen/Qwen3.6-27B --host 0.0.0.0 --port 8000 --served-model-name Qwen3.6-27B --uvicorn-log-level error --gpu-memory-utilization 0.9 --tensor-parallel-size 1 --enable-prefix-caching --enable-auto-tool-choice --tool-call-parser qwen3_coder --reasoning-parser qwen3 --max-model-len 64000 --max-num-seqs 2 --max-num-batched-tokens 4096 --limit-mm-per-prompt {"image": 8, "video": 0} --kv-cache-dtype auto --disable-log-stats --enable-sleep-mode
Apr 24 at 09:23:03.779
(APIServer pid=22) INFO 04-24 16:23:03 [utils.py:299]
(APIServer pid=22) INFO 04-24 16:23:03 [utils.py:299] █ █ █▄ ▄█
(APIServer pid=22) INFO 04-24 16:23:03 [utils.py:299] ▄▄ ▄█ █ █ █ ▀▄▀ █ version 0.19.1
(APIServer pid=22) INFO 04-24 16:23:03 [utils.py:299] █▄█▀ █ █ █ █ model Qwen/Qwen3.6-27B
(APIServer pid=22) INFO 04-24 16:23:03 [utils.py:299] ▀▀ ▀▀▀▀▀ ▀▀▀▀▀ ▀ ▀
(APIServer pid=22) INFO 04-24 16:23:03 [utils.py:299]

Can you share your vllm arguments?

try this param
vllm serve "Qwen/Qwen3.6-27B-FP8"
--host 0.0.0.0
--port 8002
--enable-chunked-prefill
--max-model-len 80000
--tensor-parallel-size 2
--gpu-memory-utilization 0.8
--enable-auto-tool-choice
--tool-call-parser qwen3_coder
--reasoning-parser qwen3 \

i deployed this model with vLLM (v 0.18.0) too using that command and no issues (on 2x L40s)

Thank you guys, I know the problem now.
In my LiteLLM, there are some different OpenAI compatible API providers. I just happened to choose one of them that output garbage values. Not sure why but picking a different OpenAI compatible provider then it works!

andylele changed discussion status to closed

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