  Graph Neural Networks (GNNs) have revolutionized many Machine Learning (ML)
applications, such as social network analysis, bioinformatics, etc. GNN
inference can be accelerated by exploiting data sparsity in the input graph,
vertex features, and intermediate data in GNN computations. For dynamic
sparsity exploitation, we leverage the heterogeneous computing capabilities of
AMD Versal ACAP architecture to accelerate GNN inference. We develop a custom
hardware module that executes the sparse primitives of the computation kernel
on the Programmable Logic (PL) and efficiently computes the dense primitives
using the AI Engine (AIE). To exploit data sparsity during inference, we devise
a runtime kernel mapping strategy that dynamically assigns computation tasks to
the PL and AIE based on data sparsity. Our implementation on the VCK5000 ACAP
platform leads to superior performance compared with the state-of-the-art
implementations on CPU, GPU, ACAP, and other custom GNN accelerators. Compared
with these implementations, we achieve significant average runtime speedup
across various models and datasets of 162.42x, 17.01x, 9.90x, and 27.23x,
respectively. Furthermore, for Graph Convolutional Network (GCN) inference, our
approach leads to a speedup of 3.9-96.7x compared to designs using PL only on
the same ACAP device.
