Add InternVL3-8B-Instruct contrib model

[jimburtoft]

Note: The below template includes items meant for model contributions only. For other contributions such as bug fixes, features, etc., only fill out the relevant portions of the form.

Description

InternVL3-8B-Instruct VLM (vision-language model) for Neuron inference via the NeuronBaseForImageToText framework. Architecture: InternViT-300M vision encoder + pixel shuffle MLP projector + Qwen2.5-7B text backbone (~8B total parameters, BF16).

Validated on trn2.3xlarge (LNC=2, TP=4) with logit_validation passing, 75.1 tok/s text generation, and end-to-end multimodal inference.

Model Information

Model Name: InternVL3-8B-Instruct

Model Architecture: Vision-language model (InternViT-300M encoder + Qwen2.5-7B decoder)

Purpose: Multimodal text generation (image-to-text, visual question answering, text-only chat)

Checklist

Please ensure your PR includes the following items. Refer to the contrib/CONTRIBUTING.md for detailed guidelines.

Required Components

• Accuracy Test (ex. test/integration/test_model.py)

  • Integration test validates model accuracy using torch_neuronx.testing.validation.logit_validation
  • Generates CPU FP32 reference logits via generate_expected_logits, compares against Neuron BF16 output
  • Handles TP vocab padding (151674 → 151676) by truncating to TP-aligned boundary
  • BF16-appropriate tolerance map (top-5: 0.05, top-50: 0.06, all: 0.08)
  • 2/2 tests pass on trn2.3xlarge

• README.md with the following sections:

  • Usage Example: Compile and run examples for text-only and multimodal inference
  • Compatibility Matrix: Validated on trn2.3xlarge (LNC=2, TP=4) with SDK 2.29
  • Example Checkpoints: OpenGVLab/InternVL3-8B-Instruct
  • Testing Instructions: pytest test/integration/test_model.py -v --tb=short

• Source Code (src/)

  • modeling_internvl3.py: Top-level VLM (NeuronBaseForImageToText)
  • modeling_internvl3_text.py: Text backbone (Qwen2.5-7B with vision embedding injection)
  • modeling_internvl3_vision.py: Vision encoder (InternViT-300M, torch_neuronx.trace)

Optional Components

• Unit Tests (CPU or Neuron-based)
  • test/unit/__init__.py exists (placeholder for future tests)

Folder Structure

Confirm your contribution follows this structure:

/contrib/models/InternVL3-8B-Instruct/
  README.md
  compile_internvl3_vlm.py
  /src
    __init__.py
    modeling_internvl3.py
    modeling_internvl3_text.py
    modeling_internvl3_vision.py
  /test
    __init__.py
    /unit
      __init__.py
    /integration
      __init__.py
      test_model.py

Testing

How did you test this change?

All tests run on trn2.3xlarge (LNC=2, TP=4) with Neuron SDK 2.29.

1. Model compiled using compile_internvl3_vlm.py (text CTE+TKG + vision encoder NEFFs)
2. Integration test test_model.py runs:
   • test_config: Validates InternVL3 config matches expected Qwen2.5-7B architecture (7 assertions)
   • test_text_logit_validation: CPU FP32 reference logits (16 tokens) compared against Neuron BF16 via logit_validation() with per-tier tolerances

Test Results:

test/integration/test_model.py::TestInternVL3Integration::test_config PASSED
test/integration/test_model.py::TestInternVL3Integration::test_text_logit_validation PASSED

Summary: Max divergence difference = 0
  Top k = 5  max error = 0.036 (tol: 0.05)
  Top k = 50 max error = 0.048 (tol: 0.06)
  Top k = 1000 max error = 0.050 (tol: 0.06)
  Top k = None max error = 0.063 (tol: 0.08)

======================= 2 passed in 26.82s ========================

Compatibility

Tested with:

• Neuron SDK Version(s): 2.29 (NxDI 0.9.17334, neuronx-cc 2.24.5133.0)
• Instance Type(s): trn2.3xlarge (LNC=2, TP=4)
• PyTorch Version: 2.9
• Python Version: 3.12.3

Additional Information

• Performance: 75.1 tok/s (BS=1, seq_len=2048), TTFT 138ms. 1.85x faster than L40S GPU.
• Vision encoder: Compiled via torch_neuronx.trace() with --auto-cast=matmult -O1. 34.5ms per 448x448 tile.
• TP vocab padding: InternVL3 vocab_size (151674) is not divisible by TP=4, so lm_head pads to 151676. The test truncates logits to the TP-aligned boundary (151672) to avoid false failures from padding artifacts.
• Maintainer: Jim Burtoft (@jimburtoft)

Related Issues

N/A

vLLM Integration

• This model/feature is intended for use with vLLM
• Documentation includes vLLM registration instructions

vLLM integration requires patches to vllm-neuron's model loader to register the InternVL3 architecture. See README for details.

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By submitting this PR, I confirm that:

• I have read and followed the contributing guidelines
• This is a community contribution and may have limited testing compared to officially-supported models
• The code follows best practices and is well-documented
• All required components listed above are included