Workload-Balanced Graph Attention Network Accelerator with Top-K Aggregation Candidates

Graph attention networks (GATs) are gaining attention for various transductive and inductive graph processing tasks due to their higher accuracy than conventional graph convolutional networks (GCNs). The power-law distribution of real-world graph-structured data, on the other hand, causes a severe workload imbalance problem for GAT accelerators. To reduce the degradation of PE utilization due to the workload imbalance, we present algorithm/hardware co-design results for a GAT accelerator that balances workload assigned to processing elements by allowing only K neighbor nodes to participate in aggregation phase. The proposed model selects the K neighbor nodes with high attention scores, which represent relevance between two nodes, to minimize accuracy drop. Experimental results show that our algorithm/hardware co-design of the GAT accelerator achieves higher processing speed and energy efficiency than the GAT accelerators using conventional workload balancing techniques. Furthermore, we demonstrate that the proposed GAT accelerators can be made faster than the GCN accelerators that typically process smaller number of computations.