Rank and File: MatryoshkaLoRA Turns One Adapter into Many
The adapter budget problem is not just training cost Budget is usually where fine-tuning conversations become less glamorous. A team wants a customized model. The engineer suggests LoRA because full fine-tuning is expensive. Everyone nods. Then the uncomfortable question arrives: which rank? A low rank is cheap but may underfit. A high rank may work better but costs more memory and inference compute. So the team trains several adapters, compares them, chooses one, and pretends the search process was a minor detail. It was not. It was the hidden invoice. ...