Head-wise Shareable Attention for Large Language Models
Zouying Cao Yifei Yang Hai Zhao
Large Language Models (LLMs) suffer from huge number of parameters, which
restricts their deployment on edge devices. Weight sharing is one promising
solution that encourages weight reuse, effectively reducing memory usage with
less performance drop. However, current weight sharing techniques primarily
focus on small-scale models like BERT and employ coarse-grained sharing rules,
e.g., layer-wise. This becomes limiting given the prevalence of LLMs and
sharing an entire layer or block obviously diminishes the flexibility of weight
sharing. In this paper, we present a perspective on $\textit{$\textbf{head-wise
shareable attention for large language models}$}$. We further propose two
memory-efficient methods that share parameters across attention heads, with a
specific focus on LLMs. Both of them use the same dynamic strategy to select
the shared weight matrices. The first method directly reuses the pre-trained
weights without retraining, denoted as $\textbf{DirectShare}$. The second
method first post-trains with constraint on weight matrix similarity and then
shares, denoted as $\textbf{PostShare}$. Experimental results reveal our
head-wise shared models still maintain satisfactory capabilities, demonstrating
the feasibility of fine-grained weight sharing applied to LLMs.