Performance-Adaptive Sampling Strategy Towards Fast and Accurate Graph Neural Networks

ABSTRACTThe main challenge of adapting Graph convolutional networks (GCNs) to large-scale graphs is the scalability issue due to the uncontrollable neighborhood expansion in the aggregation stage. Several sampling algorithms have been proposed to limit the neighborhood expansion. However, these algorithms focus on minimizing the variance in sampling to approximate the original aggregation. This leads to two critical problems: 1) low accuracy because the sampling policy is agnostic to the performance of the target task, and 2) vulnerability to noise or adversarial attacks on the graph. In this paper, we propose a performance-adaptive sampling strategy PASS that samples neighbors informative for a target task. PASS optimizes directly towards task performance, as opposed to variance reduction. PASS trains a sampling policy by propagating gradients of the task performance loss through GCNs and the non-differentiable sampling operation. We dissect the back-propagation process and analyze how PASS learns from the gradients which neighbors are informative and assigned high sampling probabilities. In our extensive experiments, PASS outperforms state-of-the-art sampling methods by up to 10% accuracy on public benchmarks and up to 53% accuracy in the presence of adversarial attacks.