  This paper introduces an efficient strategy to transform Large Language
Models (LLMs) into Multi-Modal Large Language Models (MLLMs). By
conceptualizing this transformation as a domain adaptation process, i.e.,
transitioning from text understanding to embracing multiple modalities, we
intriguingly note that, within each attention block, tuning LayerNorm suffices
to yield strong performance. Moreover, when benchmarked against other tuning
approaches like full parameter finetuning or LoRA, its benefits on efficiency
are substantial. For example, when compared to LoRA on a 13B model scale,
performance can be enhanced by an average of over 20% across five multi-modal
tasks, and meanwhile, results in a significant reduction of trainable
parameters by 41.9% and a decrease in GPU memory usage by 17.6%. On top of this
LayerNorm strategy, we showcase that selectively tuning only with
conversational data can improve efficiency further. Beyond these empirical
outcomes, we provide a comprehensive analysis to explore the role of LayerNorm
in adapting LLMs to the multi-modal domain and improving the expressive power
of the model.
