We implement a differentiable Neural Architecture Search (NAS) method inspired by FBNet for discovering neural networks that are heavily optimized for a particular target device. The FBNet NAS method discovers a neural network from a given search space by optimizing over a loss function which accounts for accuracy and target device latency. We extend this loss function by adding an energy term. This will potentially enhance the hardware awareness" and help us find a neural network architecture that is optimal in terms of accuracy, latency and energy consumption, given a target device (Raspberry Pi in our case). We name our trained child architecture obtained at the end of search process as Hardware Aware Neural Network Architecture (HANNA). We prove the efficacy of our approach by benchmarking HANNA against two other state-of-the-art neural networks designed for mobile embedded applications, namely MobileNetv2 and CondenseNet for CIFAR-10 dataset. Our results show that HANNA provides a speedup of about 2.5x and 1.7x, and reduces energy consumption by 3.8x and 2x compared to MobileNetv2 and CondenseNet respectively. HANNA is able to provide such significant speedup and energy efficiency benefits over the state-of-the-art baselines at the cost of a tolerable 4-5 drop in accuracy.
Designing convolutional neural networks (CNN) models for mobile devices is challenging because mobile models need to be small and fast, yet still accurate. Although significant effort has been dedicated to design and improve mobile models on all three dimensions, it is challenging to manually balance these trade-offs when there are so many architectural possibilities to consider. In this paper, we propose an automated neural architecture search approach for designing resource-constrained mobile CNN models. We propose to explicitly incorporate latency information into the main objective so that the search can identify a model that achieves a good trade-off between accuracy and latency. Unlike in previous work, where mobile latency is considered via another, often inaccurate proxy (e.g., FLOPS), in our experiments, we directly measure real-world inference latency by executing the model on a particular platform, e.g., Pixel phones. To further strike the right balance between flexibility and search space size, we propose a novel factorized hierarchical search space that permits layer diversity throughout the network. Experimental results show that our approach consistently outperforms state-of-the-art mobile CNN models across multiple vision tasks. On the ImageNet classification task, our model achieves 74.0 top-1 accuracy with 76ms latency on a Pixel phone, which is 1.5x faster than MobileNetV2 ( 2018) and 2.4x faster than NASNet ( 2018) with the same top-1 accuracy. On the COCO object detection task, our model family achieves both higher mAP quality and lower latency than MobileNets.