Sequence Packing for LLM Training: Eliminating Padding Waste
A practical guide to sequence packing for ML engineers training LLMs: measuring padding waste and estimating speedup, greedy packing implementation with EOS separation, the attention leakage problem in naive packing, document-aware attention masks with Flash Attention cu_seqlens, TRL SFTTrainer packing configuration, and how to verify packing efficiency and model quality after implementation.