Coarse-Grained Reconfigurable Architectures (CGRA) is a promising solution for accelerating computation intensive tasks due to its good trade-off in energy efficiency and flexibility. One of the challenging research topic is how to effectively deploy loops onto CGRAs within acceptable compilation time. Modulo scheduling (MS) has shown to be efficient on deploying loops onto CGRAs. Existing CGRA MS algorithms still suffer from mapping loop with higher performance under acceptable compilation time, especially mapping large and irregular loops onto CGRAs with limited computational and routing resources. This is mainly due to the under utilization of the available buffer resources on CGRA, unawareness of critical mapping constraints and time consuming method of solving temporal and spatial mapping. This paper focus on improving the performance and compilation robustness of the modulo scheduling mapping algorithm for CGRAs. We decomposes the CGRA MS problem into the temporal and spatial mapping problem and reorganize the processes inside these two problems. For the temporal mapping problem, we provide a comprehensive and systematic mapping flow that includes a powerful buffer allocation algorithm, and efficient interconnection & computational constraints solving algorithms. For the spatial mapping problem, we develop a fast and stable spatial mapping algorithm with backtracking and reordering mechanism. Our MS mapping algorithm is able to map loops onto CGRA with higher performance and faster compilation time. Experiment results show that given the same compilation time budget, our mapping algorithm generates higher compilation success rate. Among the successfully compiled loops, our approach can improve 5.4% to 14.2% performance and takes x24 to x1099 less compilation time in average comparing with state-of-the-art CGRA mapping algorithms.

Convolutional neural networks (CNNs) have had great success when applied to computer vision technology, and many application-specific integrated circuit (ASIC) and field-programmable gate array (FPGA) CNN accelerators have been proposed. These accelerators primarily focus on the acceleration of a single input, and they are not particularly optimized for video applications. In this article, we focus on the similarities between continuous inputs in video, and we propose a YOLOv3-tiny CNN FPGA accelerator using incremental operation. The accelerator can skip the convolution operation of similar data between continuous inputs. We also use the Winograd algorithm to optimize the conv $3\times 3$ operator in the YOLOv3-tiny network to further improve the accelerator’s efficiency. Experimental results show that our accelerator achieved 74.2 frames/s on ImageNet ILSVRC2015. Compared to the original network without Winograd algorithm and incremental operation, our design provides a $4.10\times $ speedup. When compared with other YOLO network FPGA accelerators applied to video applications, our design provided a $3.13\times $ – $18.34\times $ normalized digital signal processor (DSP) efficiency and $1.10\times $ – $14.2\times $ energy efficiency.

Deep learning accelerators have emerged to enable energy-efficient and high-throughput inference from edge devices such as self-driving cars and smartphones, to data centers for batch inference such as recommendation systems. However, the actual energy efficiency and throughput of a deep learning accelerator depends on the deep neural network (DNN) loop nest mapping on the processing element array of an accelerator. Moreover, the efficiency of a mapping dramatically changes by the target DNN layer dimensions and available hardware resources. Therefore, the optimal mapping search problem is a non-trivial high-dimensional optimization problem. Although several tools and frameworks exist for compiling to CPUs and GPUs, we lack similar tools for deep learning accelerators. To deal with the optimized mapping search problem in deep learning accelerators, we propose mRNA (mapper for reconfigurable neural accelerators), which automatically searches optimal mappings using heuristics based on domain knowledge about deep learning and an energy/runtime cost evaluation framework. mRNA targets MAERI, a recently proposed open-source deep learning accelerator that provides flexibility via reconfigurable interconnects, to run the unique mappings for each layer generated by mRNA. In realistic machine learning workloads from MLPerf, the optimal mappings identified by mRNA framework provides 15% to 26% lower runtime and 55% to 64% lower energy for convolutional layers and 24% to 67% lower runtime and maximum 67% lower energy for fully connected layers compared to simple reference mappings manually picked for each layer.

Much attention is being paid to using high-performance convolutional neural networks (CNNs) in the area of ship detection in optical remoting sensing (ORS) images. However, the problem of false negatives (FNs) caused by side-by-side ships cannot be solved, and the number of false positives (FPs) remains high. This paper uses a DLA-34 network with deformable convolution layers as the backbone. The network has two priority branches: a recall-priority branch for reducing the number of FNs, and a precision-priority branch for reducing the number of FPs. In our single-shot detection method, the recall-priority branch is based on an anchor-free module without non-maximum suppression (NMS), while the precision-priority branch utilizes an anchor-based module with NMS. We perform recall-priority branch functions based on the output part of the CenterNet object detector to precisely predict center points of bounding boxes. The Bidirectional Feature Pyramid Network (BiFPN), combined with the inference part of YOLOv3, is used to improve the precision of precision-priority branch. Finally, the boxes from two branches merge, and we propose priority-based selection (PBS) for choosing the accurate ones. Results show that our proposed method sharply improves the recall rate of side-by-side ships and significantly reduces the number of false alarms. Our method also achieves the best trade-off on our improved version of HRSC2016 dataset, with 95.57% AP at 56 frames per second on an Nvidia RTX-2080 Ti GPU. Compared with the HRSC2016 dataset, not only are our annotations more accurate, but our dataset also contains more images and samples. Our evaluation metrics also included tests on small ships and incomplete forms of ships.