HyperGRAF: Hyperdimensional Graph-based Reasoning Acceleration on FPGA

The latest hardware accelerators proposed for graph applications primarily focus on graph neural networks (GNNs) and graph mining. High-level graph reasoning tasks, such as graph memorization and neighborhood reconstruction, have barely been addressed. Compared to low-level learning applications like node classification and clustering, high-level reasoning typically requires a more complex model to mimic human brain functionalities. Brain-inspired Hyper-Dimensional Computing (HDC) has recently introduced a promising lightweight and efficient machine learning solution, particularly for symbolic representation. General-purpose computing platforms (CPU/GPU) have been revealed to be inefficient for HDC applications. Therefore, it becomes essential to design a domain-specific accelerator targeting HDC-based graph reasoning algorithms. In this work, we propose the first domain-specific accelerator for HDC-based graph reasoning, HyperGRAF. We first develop a scheduler to balance the sparse matrix computation workloads, before parallelizing the hypervector calculations on two levels for the graph memorization task. Finally, we design a pipeline-style matrix multiplication accelerator for the neighborhood reconstruction task. We evaluate our design under a wide range of generated graphs with different sizes and sparsity. The results show that HyperGRAF achieves over 100x improvement in both speedup and energy efficiency of graph reasoning compared to NVIDIA Jetson Orin.