ALTO: Adaptive LoRA Tuning and Orchestration for Heterogeneous LoRA Training Workloads

TL;DR

ALTO is a system that accelerates hyperparameter tuning for LoRA in large language models, improving efficiency and GPU utilization in multi-task environments.

Contribution

ALTO introduces a co-designed training system that optimizes LoRA tuning and cluster sharing, leveraging loss monitoring and novel parallelism techniques.

Findings

Achieves up to 13.8× speedup over existing methods

Effectively terminates unpromising configurations early

Improves GPU utilization in heterogeneous multi-task settings

Abstract

Low-Rank Adaptation (LoRA) is now the dominant method for parameter-efficient fine-tuning of large language models, but achieving a high-quality adapter often requires systematic hyperparameter tuning because LoRA performance is highly sensitive to configuration choices. In practice, this leads to many concurrent LoRA jobs, often spanning heterogeneous tasks in multi-tenant environments. Existing systems largely handle these jobs independently, which both wastes computation on weak candidates and leaves GPUs underutilized. We present ALTO (Adaptive LoRA Tuning and Orchestration), a co-designed training system that accelerates LoRA hyperparameter tuning while enabling efficient cluster sharing across heterogeneous tasks. The central insight behind ALTO is that when multiple tuning jobs run concurrently over a shared frozen backbone, they expose optimization opportunities that single-job designs cannot exploit. Building on this, ALTO monitors loss trajectories to terminate unpromising configurations early, uses fused grouped GEMM together with a new rank-local adapter parallelism to co-locate surviving adapters and reclaim freed GPU capacity, and combines intra-task and inter-task scheduling to improve multi-task placement by leveraging the predictable duration of LoRA jobs. Extensive evaluation shows that ALTO achieves up to $13.8\times$ speedup over state-of-the-art without sacrificing adapter quality.