Reliability analysis of hardware accelerators for decision tree-based classifier systems

The increasing adoption of AI models has driven applications toward the use of hardware accelerators to meet high computational demands and strict performance requirements. Beyond consideration of performance and energy efficiency, explainability and reliability have emerged as pivotal requirements, particularly for critical applications such as automotive, medical, and aerospace systems. Among the various AI models, Decision Tree Ensembles (DTEs) are particularly notable for their high accuracy and explainability. Moreover, they are particularly well-suited for hardware implementations, enabling high-performance and improved energy efficiency. However, a frequently overlooked aspect of DTEs is their reliability in the presence of hardware malfunctions. While DTEs are generally regarded as robust by design, due to their redundancy and voting mechanisms, hardware faults can still have catastrophic consequences. To address this gap, we present an in-depth reliability analysis of two types of DTE hardware accelerators: classical and approximate implementations. Specifically, we conduct a comprehensive fault injection campaign, varying the number of trees involved in the classification task, the approximation technique used, and the tolerated accuracy loss, while evaluating several benchmark datasets. The results of this study demonstrate that approximation techniques have to be carefully designed, as they can significantly impact resilience. However, techniques that target the representation of features and thresholds appear to be better suited for fault tolerance.