Energy efficiency and memory footprint of a convolutional neural network (CNN) implemented on a CNN inference accelerator depend on many factors, including a weight quantization strategy (i.e., data types and bit-widths) and mapping (i.e., placement and scheduling of DNN elementary operations on hardware units of the accelerator). We show that enabling rich mixed quantization schemes during the implementation can open a previously hidden space of mappings that utilize the hardware resources more effectively. CNNs utilizing quantized weights and activations and suitable mappings can significantly improve trade-offs among the accuracy, energy, and memory requirements compared to less carefully optimized CNN implementations. To find, analyze, and exploit these mappings, we: (i) extend a general-purpose state-of-the-art mapping tool (Timeloop) to support mixed quantization, which is not currently available; (ii) propose an efficient multi-objective optimization algorithm to find the most suitable bit-widths and mapping for each DNN layer executed on the accelerator; and (iii) conduct a detailed experimental evaluation to validate the proposed method. On two CNNs (MobileNetV1 and MobileNetV2) and two accelerators (Eyeriss and Simba) we show that for a given quality metric (such as the accuracy on ImageNet), energy savings are up to 37% without any accuracy drop.

卷积神经网络（CNN）的能效和内存占用取决于权重量化策略和映射，通过启用丰富的混合量化方案，我们可以找到更有效利用硬件资源的映射，从而在精度、能耗和内存要求之间取得更好的平衡。通过扩展Timeloop工具，提出了一种高效的多目标优化算法，实证了该方法在两种CNN和两种加速器上的有效性，并证明了相对于未经精心优化的CNN实现，可以实现高达37%的能量节省，而无需降低精度。

深度神经网络加速器中的量化和映射协同探索