MOZART: Masking Outputs with Zeros for Architectural Robustness and Testing of DNN Accelerators

Abstract

Deep Neural Networks (DNNs) are increasingly used in safety critical autonomous systems. In this paper, we present MOZART, a DNN accelerator architecture which provides fault detection and fault tolerance. MOZART is a systolic architecture based on the Output Stationary (OS) variant, as it is the one that inherently limits fault propagation. In addition, MOZART achieves fault detection with on-line functional testing of the Processing Elements (PEs). Faulty PEs are swiftly taken off-line with minimal classification impact. The implementation of our approach on Squeezenet results in a loss of accuracy of less than 3% in the presence of a single faulty PE, compared to 15-33% without mitigation. The area overhead for the test logic does not exceed 8%. Dropout during training further improves fault tolerance, without a priori knowledge of the faults.