DEV Community

Bohdan Hordii
Bohdan Hordii

Posted on Originally published at bohdanhordii.dev

Why MuonGS Beats AdamW and Muon in LLM Pretraining

Standard AdamW and vanilla Muon waste millions of GPU hours during LLM pretraining because uncontrolled weight-norm growth throttles the effective learning rate. We cannot keep burning H100 clusters on sub-optimal trajectory dynamics when Gram-Schmidt projection gives us direct mathematical control over weight exploration.

Here is how MuonGS fundamentally shifts pretraining economics:

  • 15% Token-Equivalent Compute Reduction: On 400M dense and 1B parameter MoE architectures, MuonGS reached matched validation perplexity 15% faster than MuonH, slashing hundreds of GPU cluster hours.
  • Strict Norm Growth Bounds ($O(\sqrt{t})$): By removing the radial update component via Gram-Schmidt projection, the Frobenius norm $|W_t|_F$ grows at most sublinearly instead of stalling accumulation logarithmically, guaranteeing sustained exploration ($C_T = \Omega(\sqrt{T})$).
  • Zero Additional VRAM Allocation: Unlike heavy second-order optimizers that demand massive auxiliary state matrices, MuonGS executes purely in-place tensor operations with negligible step latency impact inside standard CUDA cgroups.

The one real trade-off is architectural sensitivity: Gram-Schmidt projection assumes smooth scale-invariant layers. Non-normalized components like token embeddings and language model output heads still require segregated coordinate-wise schedulers or traditional AdamW branches.

The Question to You: What is your team using for foundation pretraining and long-horizon fine-tuning in 2026? Are you still defaulting to AdamW, or running Muon and SOAP in production? Drop your stack below.

Bohdan Hordii // Systems & Sovereign Infrastructure Architect | bohdanhordii.dev

Top comments (0)