Building Gautama-VLM 3B - an open, efficient Vision-Language Model trained end-to-end on a single GPU
๐ต Ganga Taranaga โ background music
Gautama-AI proposes to train a complete 3.33-billion-parameter Vision-Language Model from scratch โ a GPT-style language model that also sees and understands images โ on a single NVIDIA H100 GPU, in 89 days. The result is a fully open model, tokenizer, dataset recipe, and training pipeline that anyone can reproduce, study, and build on.
Frontier VLMs cost millions of dollars and thousands of GPUs to train. This project demonstrates that a genuinely capable multimodal model โ image captioning, visual question answering, chart reading, document understanding, and 16K-token long-context reasoning โ is achievable at hobbyist-accessible budgets by combining a carefully engineered architecture with cutting-edge training efficiency research, including Lighthouse Attention (Nous Research, 2026) for long-context training.
GPT-style decoder-only Transformer: 28 layers, 3072-dim, grouped-query attention, RoPE, SwiGLU, RMSNorm. Same architecture family as Llama โ fully compatible with the open-source ecosystem.
CLIP ViT-L/14 encodes any image into 257 visual tokens. The language model attends to these tokens exactly like text โ one unified sequence, one unified model.
A compact 2-layer MLP that translates vision features into the language model's embedding space โ the bridge that turns a GPT into a VLM.
Lighthouse Attention โ a 2026 hierarchical attention method โ extends the model from 4K to 16K tokens with full dense-attention quality recovered before release.
With no image, Gautama-VLM behaves as a pure GPT: completion, Q&A, reasoning, code. With an image, it becomes a visual assistant: describe, answer, read charts, extract text. The same 3.33B weights serve both.
The H100's 80 GB is used at 85% during peak training โ achieved through fp32-master AdamW, activation checkpointing, and chunked cross-entropy (which cuts the loss computation's memory peak from 9.8 GB to 0.6 GB). A smaller model would waste the hardware; a larger one would not fit. 3B is the engineered sweet spot.
Standard attention cost grows quadratically with context length โ the main reason long-context training is expensive. Lighthouse Attention (Peng, Ghosh & Quesnelle, Nous Research, arXiv:2605.06554) pools queries, keys, and values into a multi-resolution pyramid, selects the most important entries with a parameter-free scorer, and runs standard FlashAttention on the compressed sequence โ then a brief dense-attention resumption restores full quality. The paper demonstrates 1.4โ1.7ร faster training at equal or better final loss.
| Training sub-phase | Tokens | GPU hours |
|---|---|---|
| D1 ยท Text pretraining (seq 4K) | 30B | 378.3 |
| D2 ยท Long-context extension @16K (Lighthouse) | 5B | 54 |
| D3 ยท Vision alignment (projector) | 0.5B | 2.1 |
| D4 ยท VLM instruction tuning | 5B | 68.8 |
| D5 ยท DPO preference alignment | 0.2B | 2.8 |
| Spot interruption buffer | โ | 60 |
| Total | 40.7B | 566 |
Throughput 22,026 tok/s at 45% MFU on H100 SXM5 (989 TFLOPS BF16) โ all figures derived from the project's own planning calculator and cross-checked against the model code.
| Capability | Benchmark | Target |
|---|---|---|
| Common-sense reasoning | HellaSwag (0-shot) | โฅ 62% |
| World knowledge | MMLU (5-shot) | โฅ 46% |
| Long-context recall @16K | Needle-in-a-Haystack | โฅ 70% |
| Visual question answering | VQAv2 (test-dev) | โฅ 60% |
| Visual reasoning | GQA | โฅ 58% |
| Text-in-image reading | TextVQA | โฅ 45% |
| Hallucination control | POPE (F1) | โฅ 80% |
| Deployment footprint | GGUF q4_k_m size | โค 2.5 GB |