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FP4 All the Way: Fully Quantized Training of LLMs

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arxiv 2505.19115 v2 pith:DQB64XYZ submitted 2025-05-25 cs.LG cs.AI

FP4 All the Way: Fully Quantized Training of LLMs

classification cs.LG cs.AI
keywords trainingquantizedblockeffectivefullyllmsmodelrounding
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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We demonstrate, for the first time, fully quantized training (FQT) of large language models (LLMs) using predominantly 4-bit floating-point (FP4) precision for weights, activations, and gradients on datasets up to 200 billion tokens. We extensively investigate key design choices for FP4, including block sizes, scaling formats, and rounding methods. Our analysis shows that the NVFP4 format, where each block of 16 FP4 values (E2M1) shares a scale represented in E4M3, provides optimal results. We use stochastic rounding for backward and update passes and round-to-nearest for the forward pass to enhance stability. Additionally, we identify a theoretical and empirical threshold for effective quantized training: when the gradient norm falls below approximately $\sqrt{3}$ times the quantization noise, quantized training becomes less effective. Leveraging these insights, we successfully train a 7-billion-parameter model on 256 Intel Gaudi2 accelerators. The resulting FP4-trained model achieves downstream task performance comparable to a standard BF16 baseline, confirming that FP4 training is a practical and highly efficient approach for large-scale LLM training. A reference implementation is supplied in https://github.com/Anonymous1252022/fp4-all-the-way .

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Forward citations

Cited by 25 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Grid Games: The Power of Multiple Grids for Quantizing Large Language Models

    cs.LG 2026-05 accept novelty 8.0

    Allowing each quantization group to select among multiple 4-bit grids improves accuracy over single-grid FP4 for both post-training and pre-training of LLMs.

  2. Full-Stack FP4: Stable LLM Pretraining with Quantized Projections, Optimizers, and Attention

    cs.LG 2026-07 conditional novelty 7.0

    Full-stack NVFP4 LLM pretraining is stable with a 1.47% loss gap to BF16 via LoRA-SVD projections, transformed AdamW/Root optimizers, and mixed-precision attention.

  3. LongLive-2.0: An NVFP4 Parallel Infrastructure for Long Video Generation

    cs.CV 2026-05 unverdicted novelty 7.0

    LongLive-2.0 delivers an NVFP4 parallel infrastructure that enables direct training of long multi-shot autoregressive diffusion video models and achieves up to 2.15x training and 1.84x inference speedups on Blackwell ...

  4. Pretraining large language models with MXFP4 on Native FP4 Hardware

    cs.LG 2026-05 unverdicted novelty 7.0

    Weight-gradient quantization drives most convergence problems in MXFP4 pretraining of Llama 3.1-8B; deterministic Hadamard rotations stabilize training by correcting structured micro-scaling errors.

  5. Four Over Six: More Accurate NVFP4 Quantization with Adaptive Block Scaling

    cs.CL 2025-12 conditional novelty 7.0

    Four Over Six adaptively scales blocks in NVFP4 quantization to smaller FP4 values, making representable value distributions more uniform and reducing quantization error especially for near-maximal values.

  6. GyRot: Leveraging Hidden Synergy between Rotation and Fine-grained Group Quantization for Low-bit LLM Inference

    cs.AR 2026-07 conditional novelty 6.0

    Rotation and fine-grained group quantization can work together if rotation spans several quantization groups and outlier channels are permuted onto harmonic Hadamard rows, enabling 4-bit LLM inference with integer-onl...

  7. Stable FP4 Training via Transposition-Invariant Block Quantization

    cs.LG 2026-07 conditional novelty 6.0

    Transposition-invariant 2D block FP4 quantization plus truncation-free scaling and stochastic rounding enables stable end-to-end FP4 LLM training within ~1% of BF16.

  8. SharQ: Bridging Activation Sparsity and FP4 Quantization for LLM Inference

    cs.LG 2026-06 unverdicted novelty 6.0

    SharQ combines input-adaptive N:M sparsity and FP4 quantization via sparse backbone plus dense residual, recovering 43-63% of the NVFP4-to-FP16 accuracy gap on Llama and Qwen models without calibration or retraining.

  9. ThriftAttention: Selective Mixed Precision for Long-Context FP4 Attention

    cs.LG 2026-05 unverdicted novelty 6.0

    ThriftAttention recovers 89.1% of the FP16 quality gap versus pure FP4 attention by running only 5% of query-key blocks in FP16 on long-context benchmarks.

  10. Decomposing MXFP4 quantization error for LLM reinforcement learning: reducible bias, recoverable deadzone, and an irreducible floor

    cs.LG 2026-05 unverdicted novelty 6.0

    MXFP4 quantization error decomposes into scale bias, deadzone truncation, and grid noise; mode-targeted corrections recover BF16 accuracy within 0.7% on Qwen2.5-3B and exceed it by 1.0% on Qwen3-30B-A3B.

  11. Decomposing MXFP4 quantization error for LLM reinforcement learning: reducible bias, recoverable deadzone, and an irreducible floor

    cs.LG 2026-05 unverdicted novelty 6.0

    MXFP4 error decomposes into scale bias, deadzone truncation, and grid noise that each dominate distinct RL failure modes, with macro-block scaling, outlier fallback, and adaptive noise recovering or exceeding BF16 per...

  12. Decomposing MXFP4 quantization error for LLM reinforcement learning: reducible bias, recoverable deadzone, and an irreducible floor

    cs.LG 2026-05 unverdicted novelty 6.0

    MXFP4 quantization error decomposes into scale bias, deadzone truncation, and grid noise; macro-block scaling, outlier fallback, and adaptive quantization noise recover BF16 accuracy to within 0.7% and 3.0% on tested models.

  13. Search Your Block Floating Point Scales!

    cs.LG 2026-05 unverdicted novelty 6.0

    ScaleSearch optimizes block floating point scales via fine-grained search to cut quantization error by 27% for NVFP4, improving PTQ by up to 15 points on MATH500 for Qwen3-8B and attention PPL by 0.77 on Llama 3.1 70B.

  14. LoKA: Low-precision Kernel Applications for Recommendation Models At Scale

    cs.LG 2026-05 unverdicted novelty 6.0

    LoKA enables practical FP8 use in numerically sensitive large recommendation models via online profiling of activations, reusable model modifications for stability, and dynamic kernel dispatching.

  15. LoKA: Low-precision Kernel Applications for Recommendation Models At Scale

    cs.LG 2026-05 unverdicted novelty 6.0

    LoKA enables practical FP8 use in numerically sensitive large recommendation models via profiling, model adaptations, and runtime kernel orchestration.

  16. Pretraining large language models with MXFP4 on Native FP4 Hardware

    cs.LG 2026-05 unverdicted novelty 6.0

    Weight gradient FP4 quantization drives LLM pretraining divergence, which deterministic Hadamard rotations can stabilize on native MXFP4 hardware.

  17. Pretraining large language models with MXFP4 on Native FP4 Hardware

    cs.LG 2026-05 unverdicted novelty 6.0

    Weight gradient quantization is the main driver of instability in full-pipeline FP4 LLM training, mitigated by deterministic Hadamard rotations rather than added stochasticity.

  18. LOCALUT: Harnessing Capacity-Computation Tradeoffs for LUT-Based Inference in DRAM-PIM

    cs.AR 2026-04 conditional novelty 6.0

    LOCALUT delivers 1.82x geometric mean speedup for quantized DNN inference on real UPMEM DRAM-PIM devices by using operation-packed LUTs with canonicalization, reordering, and slice streaming.

  19. AdaHOP: Fast and Accurate Low-Precision Training via Outlier-Pattern-Aware Rotation

    cs.LG 2026-04 unverdicted novelty 6.0

    AdaHOP applies pattern-aware Hadamard transforms and selective outlier extraction to enable from-scratch MXFP4 training of LLMs at BF16 quality with up to 3.6X memory compression and 1.46X speedup.

  20. ARCQuant: Boosting NVFP4 Quantization with Augmented Residual Channels for LLMs

    cs.LG 2026-01 conditional novelty 6.0

    By appending quantized residual channels to NVFP4 activations and duplicating the matching weights, ARCQuant reaches W4A8-level accuracy while keeping a single unified 4-bit GEMM.

  21. BOOST: BOttleneck-Optimized Scalable Training Framework for Low-Rank Large Language Models

    cs.LG 2025-12 unverdicted novelty 6.0

    BOOST delivers 1.46-2.27x end-to-end speedups for low-rank bottleneck LLMs by redesigning tensor parallelism around the bottleneck structure plus supporting optimizations.

  22. Not All NVFP4 QAT Recipes Are Equal: How Architecture and Scale Shape Model Quality for Anomaly Segmentation

    cs.CV 2026-05 unverdicted novelty 5.0

    Attention-based architectures like Swin Transformer show greater robustness to FP4 QAT recipe choice than CNNs across model scales in anomaly segmentation, with architecture having the largest impact.

  23. LoKA: Low-precision Kernel Applications for Recommendation Models At Scale

    cs.LG 2026-05 unverdicted novelty 5.0

    LoKA claims to make FP8 practical for large recommendation models via statistical probing, model adaptations, and accuracy-aware kernel dispatch.

  24. High-Rate Quantized Matrix Multiplication I

    cs.IT 2026-01 unverdicted novelty 5.0

    High-rate quantization theory yields accurate approximations for the distortion of absmax INT and FP schemes in generic weight-plus-activation matrix multiplication.

  25. HiFloat4 Format for Language Model Pre-training on Ascend NPUs

    cs.LG 2026-04 unverdicted novelty 4.0

    HiFloat4 FP4 with stabilization techniques trains dense and MoE language models on Ascend NPUs at relative error within 1% of full-precision baselines.