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GaLore: Memory-Efficient LLM Training by Gradient Low-Rank Projection
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Proposes GaLore, which projects weight gradients into a low-rank subspace (via periodic SVD) so Adam-style optimizer states are stored in compact form, enabling full-parameter LLM pre-training and fine-tuning with much lower memory.
Problem
Memory cost of weights, gradients and optimizer states in LLM pre-training and fine-tuning; low-rank adaptation methods like LoRA underperform full-rank training and can require full-rank warmup.
Approach
Instead of low-rank parameterizing the weights (LoRA/ReLoRA), project the gradient matrix into a low-rank subspace using SVD-derived projectors refreshed every T steps, run the optimizer on the compact projected gradient, and project the update back, so full-parameter learning is preserved while optimizer states shrink.
Key results
- On LLaMA 1B pre-training on C4, GaLore reaches validation perplexity 15.64 vs 15.56 for full-rank, with optimizer memory 4.38G vs 7.80G.
- 8-bit GaLore pre-trains LLaMA 7B to perplexity 14.65 vs 14.61 for 8-bit Adam, with total memory 22.0G (fits RTX 4090 24GB) and 63.3% total memory reduction vs BF16 Adam.
- Fine-tuning RoBERTa-Base on GLUE at rank 4, GaLore averages 85.89 vs LoRA 85.61 with 253M vs 257M memory.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Use GaLore instead of full-rank Adam training | LLaMA pre-training · C4 validation, 60M–1B models | perplexity: 34.06 -> 34.88; 25.08 -> 25.36; 18.80 -> 18.95; 15.56 -> 15.64 | Hurt |
| Use GaLore instead of LoRA | LLaMA pre-training · C4 validation, 60M–1B models | perplexity: 34.99 -> 34.88; 33.92 -> 25.36; 25.58 -> 18.95; 19.21 -> 15.64 | Helped |
| Use GaLore instead of ReLoRA | LLaMA pre-training · C4 validation, 60M–1B models | perplexity: 37.04 -> 34.88; 29.37 -> 25.36; 29.08 -> 18.95; 18.33 -> 15.64 | Mixed |
| Replace 8-bit Adam with 8-bit GaLore | LLaMA 7B pre-training · C4, 40K–150K steps | perplexity: 18.09 -> 17.94; 15.47 -> 15.39; 14.83 -> 14.95; 14.61 -> 14.65 | Mixed |
| Use GaLore rank 4 instead of LoRA rank 4 | RoBERTa-Base fine-tuning · GLUE average | average score: 85.61 -> 85.89 | Helped |
| Use GaLore rank 8 instead of LoRA rank 8 | RoBERTa-Base fine-tuning · GLUE average | average score: 85.93 -> 85.94 | No clear effect |
| Change subspace-switching frequency to be too frequent or too slow (ablation) | GaLore pre-training · C4 | convergence | Hurt |
| Reduce subspace rank (ablation) | GaLore pre-training · C4 | convergence rate | Hurt |
| Train rank 128 for 80K steps instead of rank 512 for 20K steps (ablation) | GaLore · C4 pre-training | loss: rank of 128 using 80K steps; rank of 512 using 20K steps | Helped |
Surprising findings
- GaLore with rank 1024 on 1B model slightly outperforms the full-rank baseline in perplexity (15.56 vs. 15.64 comparison noted by authors for rank 1024).
- Pure low-rank weight factorization (Low-Rank) performs far worse than LoRA and GaLore at 1B (142.53 perplexity).
Limitations
- Throughput overhead of about 17% vs 8-bit Adam in the current implementation.
- 7B pre-training compared to 8-bit Adam only with a single untuned trial due to compute constraints.
- Projection matrices themselves are not memory-optimized and are left for future work.
Experimental setup
Datasets: C4 GLUE
Benchmarks: C4 validation perplexity GLUE
Metrics: validation perplexity GLUE average score memory estimate (GB) throughput (tokens/s)
Baselines: Full-Rank Low-Rank LoRA ReLoRA 8-bit Adam Adafactor AdamW
Builds on: LoRA ReLoRA Adam 8-bit optimizers Adafactor
Closest papers by meaning
- Fira: Can We Achieve Full-rank Training of LLMs Under Low-rank Constraint? (NeurIPS 2025 · similarity 0.93)
- Gradient Weight-normalized Low-rank Projection for Efficient LLM Training (AAAI 2025 · similarity 0.92)
- AdaRankGrad: Adaptive Gradient Rank and Moments for Memory-Efficient LLMs Training and Fine-Tuning (ICLR 2025 · similarity 0.92)
- Train Small, Infer Large: Memory-Efficient LoRA Training for Large Language Models (ICLR 2025 · similarity 0.92)
- VeLoRA: Memory Efficient Training using Rank-1 Sub-Token Projections (NeurIPS 2024 · similarity 0.91)
- FRUGAL: Memory-Efficient Optimization by Reducing State Overhead for Scalable Training (ICML 2025 · similarity 0.90)
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