MoKA: Mixture of Kronecker Adapters

TL;DR

MoKA introduces a flexible, expressive Kronecker adapter for parameter-efficient fine-tuning of large language models, significantly improving performance on complex tasks while reducing trainable parameters.

Contribution

The paper proposes MoKA, a novel mixture of Kronecker adapters with gating and rank flexibility, enhancing expressiveness and hardware efficiency for LLM fine-tuning.

Findings

MoKA outperforms PEFT baselines on instruction-tuning and reasoning tasks.

Reduces trainable parameters by up to 27x.

Achieves state-of-the-art performance-parameter trade-offs.

Abstract

Parameter-efficient fine-tuning (PEFT) is essential for reducing the computational overhead of large language models (LLMs). Low-rank family adapters are commonly used to control the parameter size efficiently while maintaining the generative power of LLMs. However, their limited expressiveness due to the rank constraint often restricts their performance on complex tasks. We propose Mixture of Kronecker Adapters (MoKA), a new generation of Kronecker adapters that addresses this limitation by modeling weight updates as a mixture of Kronecker products. Our proposed adapter leverages a gating mechanism that measures the importance of each Kronecker factor, enabling more expressive adaptation. Moreover, MoKA enables a rank flexibility that provides a better trade-off between parameter efficiency and accuracy. To ensure hardware efficiency, we reformulate Kronecker computations using standard matrix operations, allowing seamless deployment on GPU-optimized hardware. We conduct extensive experiments on instruction-tuning and commonsense reasoning tasks using low-bit quantized versions of LLaMA2-7B and LLaMA3-8B models. MoKA not only outperforms PEFT baselines, but also reduces the number of trainable parameters up to 27x, achieving state-of-the-art trade-offs between performance and parameter efficiency.