adv-optm 0.1.3

A family of highly efficient, lightweight yet powerful optimizers.

Advanced Optimizers

This repo introduces a new family of highly efficient, lightweight yet powerful optimizers, born from extensive research into recent academic literature and validated through practical training runs across diverse models.

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Install

pip install adv_optm

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Theory (Inspired by SMMF)

Based primarily on:
SMMF: Square-Matricized Momentum Factorization for Memory-Efficient Optimization

The core innovation:

• Uses fast, non-negative matrix factorization (NNMF - rank 1), but reconstructs the full state before each update to preserve momentum accuracy, then re-factors afterward (factor → reconstruct → update → factor cycle).
• For the signed first moment, we split into sign + absolute value:
  • Sign is stored as 1-bit state via bitwise ops (SMMF originally used 8-bit with 7 bits wasted).
  • Absolute value goes through the factor/reconstruct cycle using two factored vectors + the signed state.
• Final storage: four factored vectors + one 1-bit sign.
• Updates behave like full-state Adam but with drastically reduced memory.

✅ TL;DR: Lightweight, strong, memory-efficient optimizer.

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Memory Cost

• Adopt_Factored for full SDXL finetune: 328 MB (4 small vectors + 1-bit state)
• Adopt_Factored with AdEMAMix for full SDXL finetune: 625 MB (6 small vectors + two 1-bit states)

SDXL is 6.5GB model.

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⏱️ Speed (my tests in SDXL - BS 4)

• Adopt_Factored: ~10s/it
• Adopt_Factored with AdEMAMix: ~12s/it
• Adafactor: ~8.5s/it
  → Overhead from compression/reconstruction cycles. → It's faster than MLorc (~12s/it), which uses RSVD compression, and should be the fastest momentum compression (AFAIK).

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📈 Performance

• Better than Adafactor, and CAME factorzation methods
• Comparable or identical to Adam (see SMMF paper results)

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Available Optimizers (all support Factored toggle)

Set Factored=False to disable factorization and run as a full uncompressed optimizer (like vanilla Adam).

1. Adam
2. Prodigy
3. Adopt

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Bonus Features (Built-in)

• Fused Backward Pass

• Stochastic Rounding (SR): Improves quality and convergence for BF16 training.

• AdEMAMix
  → This adds a second, slow-moving EMA, which is combined with the primary momentum to stabilize updates, especially during long runs of full finetuning. → A higher value of beta3 (e.g., 0.9999) gives the EMA a longer memory, making it more stable but slower to adapt. A lower value (e.g., 0.999) is often better for shorter training runs (2k-4k steps). → When factored is true, it compresses the new momentum in the same way as the first moment (1-bit state + 2 vectors). However, this introduces noticeable overhead as we are compressing/reconstructing a third state each step.

  ⚠️ Note: AdEMAMix updates are more aggressive than normal Adam/Adopt, so use a x2-x5 smaller LR than usual (or use Prodigy).

• atan2 smoothing & scaling
  → Robust eps replacement (no tuning!) + built-in gradient clipping
  → Ideal for ADOPT (which normally needs higher eps and clipping), so use_atan2 is all-in-one for it.

• OrthoGrad
  → Removes gradient component parallel to weights → prevents "naïve loss minimization" (NLM) → reduces natural overfitting
  → Perfect for fine-tuning the direction of existing features (e.g., full finetune or training a trained LoRA) without weight decay erasing prior knowledge.

  ⚠️ Note: OrthoGrad introduces ~33% time overhead, so take this into account.

• Grams: Gradient Descent with Adaptive Momentum Scaling
  → Eliminates the need for 1-bit momentum sign storage by using the sign of gradients for the first moment.

  ⚠️ Not recommended for small batch sizes: gradients are too noisy, which can destabilize momentum (tested for Prodigy and it made the optimizer slower to find the LR or converge in BS 4).

Other Notes

• Adopt skips the first step (only initializes the states) and has built-in clipping (sticking to the original optimizer), but we skip both of these when you enable use_atan2; as the optimizer becomes scale-invariant and the values of the states won't cause any issues or instability.

• When use_atan2 is True, eps will be ignored and you should also disable any gradient clipping.

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