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qwen2.5-omni: offload multimodal features to CPU after GPU processing - #41891

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MynameFelix:qwen2.5-omni-offload-multimodal-cpu
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MynameFelix wants to merge 3 commits into
vllm-project:mainfrom
MynameFelix:qwen2.5-omni-offload-multimodal-cpu

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Purpose

Fix the issue of high GPU memory usage during multimodal processing in the Qwen2.5-Omni model.

In the _call_hf_processor method, when CUDA is available and mm_kwargs does not specify a device, after multimodal feature processing is completed on the GPU, the features are immediately offloaded to CPU memory via .to("cpu").

Problems Solved

Multimodal data → GPU processing → Results stay in GPU memory → Memory always occupied
Reduce GPU memory usage, free up GPU memory resources, improve GPU utilization, and increase inference speed

Core Solution: _call_hf_processor() Feature Offloading Optimization

Condition: GPU available + No device specified
Processing Flow: Call parent class super()._call_hf_processor() to extract features, then immediately transfer features back to CPU via .to("cpu")

Test Plan

Unit Test: Use Qwen2.5-Omni model for multimodal inference (image/audio/video) to verify functional correctness and performance

Test Results

Qwen2.5-Omni (Thinker) Performance Test Report

Test Subject: MetaX Plugin Modified vs vLLM Original
Test Environment: MetaX-C500 Hardware Environment

1. Pure Text Inference

Metric Plugin Original Delta Improvement
TTFT (ms) 17.67 18.48 -0.81 ⬆️ 4.4%
TPOT (ms/token) 7.63 7.73 -0.10 ⬆️ 1.3%
ITL (ms/token) 7.63 7.73 -0.10 ⬆️ 1.3%
E2EL (ms) 962.79 976.20 -13.41 ⬆️ 1.4%
TPS (tokens/s) 127.52 125.71 +1.81 ⬆️ 1.4%

Summary: In pure text scenarios, the plugin version achieved a comprehensive slight lead with faster response speed.

2. Image Understanding

Metric Plugin Original Delta Improvement
E2EL (ms) 1355.95 1527.59 -171.64 ⬆️ 11.2%
TPS (tokens/s) 122.92 114.57 +8.35 ⬆️ 7.3%
Tokens 167.00 174.50 -7.50 -

Summary: With visual modality introduced, the plugin version's advantage expanded with significantly lower end-to-end latency.

3. Video Understanding

Metric Plugin Original Delta Improvement
E2EL (ms) 2663.95 5576.44 -2912.49 ⬆️ 52.2%
TPS (tokens/s) 28.13 13.54 +14.59 ⬆️ 107.8%
Tokens 76.00 76.00 0 -

Summary: Performance improvement in video scenarios is extremely significant. Plugin throughput (TPS) doubled, latency halved.

4. Interleaved Audio-Video

Metric Plugin Original Delta Improvement
E2EL (ms) 2219.58 5137.29 -2917.71 ⬆️ 56.8%
TPS (tokens/s) 21.01 16.34 +4.67 ⬆️ 28.6%
Tokens 51.50 84.00 -32.50 -

Summary: In the most complex multimodal interleaved scenario, the plugin version maintains huge advantages with far higher processing efficiency than the original.

Summary Comparison Table

Test Scenario E2EL Improvement TPS Improvement Performance Rating
Pure Text +1.4% +1.4% ✅ Stable slight gain
Image Understanding +11.2% +7.3% ✅ Significant acceleration
Video Understanding +52.2% +107.8% 🚀 Leap-level improvement
Interleaved Audio-Video +56.8% +28.6% 🚀 Leap-level improvement

Files Involved

  • vllm/model_executor/models/qwen2_5_omni_thinker.py

Signed-off-by: Yipeng Hu <i26268@metax-tech.com>

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Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

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github-actions Bot commented May 7, 2026

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@mergify mergify Bot added the qwen Related to Qwen models label May 7, 2026

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Code Review

This pull request modifies the Qwen2.5-Omni model by implementing device-aware offloading during processor calls and cleaning up unused parameters in audio and video processing methods. A review comment highlights a potential bug where the mm_kwargs dictionary is modified in-place, suggesting a refactor to use a copy instead to avoid side effects and reduce code duplication.

Comment thread vllm/model_executor/models/qwen2_5_omni_thinker.py
Comment on lines +481 to +499
if "device" not in mm_kwargs and torch.cuda.is_available():
mm_kwargs["device"] = "cuda"
hf_inputs = (
super()
._call_hf_processor(
prompt=prompt,
mm_data=mm_data,
mm_kwargs=mm_kwargs,
tok_kwargs=tok_kwargs,
)
.to("cpu")
)
else:
hf_inputs = super()._call_hf_processor(
prompt=prompt,
mm_data=mm_data,
mm_kwargs=mm_kwargs,
tok_kwargs=tok_kwargs,
)

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Currently, we don't expect to call hf processor on GPU, see: #22070

@mergify

mergify Bot commented Jul 18, 2026

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This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @MynameFelix.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

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