Multiobjective End-to-End Design Space Exploration of Parameterized DNN Accelerators

Deep neural network (DNN) hardware accelerators enable the execution of complex DNN inferences on resource-constrained IoT devices. Inference performance and energy figures depend on how the DNN layers are mapped into the accelerator and how the architecture of the accelerator fits the variety of layers' shapes of the actual DNN. The mapping determines the execution order of the operations, both temporally and spatially. Thus, selecting the best mapping that allows fitting the DNN model to the specific accelerator is of paramount importance to meet the strong constraints imposed by resource-scarce IoT platforms. Although several mapping space exploration techniques have been proposed in the literature, they are focused on determining the best mapping for a given layer, for a given architecture, and for optimizing a single objective. This article largely extends the scope of the exploration by considering the huge design space spanned by mapping related and architectural parameters, considering all the layers of the DNN, and optimizing multiple objectives simultaneously. We present EPOCA, end-to-end Pareto optimization of DNN accelerators, whose goal is to determine the accelerator's architecture and the mapping for each layer that optimizes end-to-end and in a multiobjective fashion a set of conflicting design criteria. We assess EPOCA on different DNN models on a parameterized hardware accelerator designed for IoT applications and compare them with a state-of-the-art mapping space explorer, considering the area, inference latency, and inference energy as optimization metrics. We show that the set of Pareto solutions found by EPOCA provides the designer with a range of choices from which to select the best tradeoff with respect to the specific application.

Automated summary

DNN hardware accelerators enable complex inferences on resource-constrained IoT devices. This article introduces EPOCA, an end-to-end Pareto optimization method for determining the accelerator's architecture and layer mappings that optimize multiple objectives simultaneously. The results show that EPOCA provides a range of choices for tradeoffs in specific applications.