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Open Access Issue
High-throughput LDPC decoder on GPU for 5G new radio
Journal of National University of Defense Technology 2024, 46(1): 141-148
Published: 28 February 2024
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A GPU (graphic processing unit) based 5G software radio quasi cyclic LDPC (low-density parity check) code decoder was proposed. In order to save on chip and off chip bandwidth, code word shortening and punching techniques, two-stage quantization, and data packaging schemes were adopted to improve the utilization of data bandwidth. The experiment was based on the Nvidia RTX 2080Ti GPU platform to achieve parallel decoding of minimum and approximate decoding algorithms under high bit rates. By analyzing the optimal thread settings on the GPU, the decoding throughput of the 5/6 (2080, 1760) LDPC algorithm is improved to 1.38 Gbit/s, and the decoding throughput performance is better than other GPU based LDPC decoders.

Open Access Issue
Parallel optimization of convolution algorithm on multi-core DSP
Journal of National University of Defense Technology 2024, 46(1): 103-112
Published: 28 February 2024
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According to the characteristics of the heterogeneous multi-core DSP (digital signal processing) chip independently developed by National University of Defense Technology and the characteristics of the convolution algorithm, a high-performance multi-core parallel convolution implementation scheme for multi-core DSP architecture was proposed. A feature graph level multi-core parallel scheme is proposed for 1 × 1 convolution. For convolutions with kernels larger than 1, a window level multi-core parallel optimization design was proposed, and an element-wise vectorization based intra-core parallel optimization implementation was proposed. The experimental results show that the proposed parallel optimization method can reach a maximum single core computing efficiency of 64.95%. When the bandwidth is limited, the parallel expansion efficiency of multi-core can still reach 48.36% ~ 88.52%. Compared with E5-2640 CPU, the execution performance on the typical network ResNet50 achieves 5.39x performance acceleration.

Open Access Issue
Optimizing operator computation of MiniGo on high-performance heterogeneous accelerator
Journal of National University of Defense Technology 2024, 46(1): 131-140
Published: 28 February 2024
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An efficient parallel computing method based on the characteristics of the high-performance heterogeneous accelerator and the training mode of MiniGo was proposed. The on-chip computing resources were reasonably planned to achieve pipelining parallel optimization between heterogeneous devices. The shared memory programming was designed according to the existence of shared storage segments between heterogeneous devices to reduce data transmission costs. According to the characteristics of multiple computing resources in a digital signal processing cluster, combined with the computing-memory access feature of the operators, different optimization strategies were designed. At the same time, this method provides an easy-use high-performance operator library for TensorFlow. The experimental results show that this method realizes the multi-core parallel computing of operators. The speedup of convolution was 24.69 compared with that was achieved on a single core. Compared with the cropped version of the 8-core FT2000 + CPU, the speedup of training and self-play execution on this method were 3.83 and 1.5, respectively.

Open Access Issue
High efficient training method of MiniGo on large-scale heterogeneous computing platform
Journal of National University of Defense Technology 2024, 46(5): 209-218
Published: 28 October 2024
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An efficient multi-level parallel training method suitable for training MiniGo agents on large-scale heterogeneous computing platforms was proposed, including task level parallelism between nodes, CPU-DSP (central processing unit-digital signal process) heterogeneous parallelism and DSP core parallelism. Efficient input/output deployment and eliminated the bottleneck of network communication were realized. A heterogeneous computing memory management oriented to CPU-DSP shared memory structure was proposed to reduce the data handling between heterogeneous devices. Shared memory programming optimization was realized, and the dense convolution calculation operator acceleration optimization was realized by DSP. Results show that compared with 16 core CPU calculation, the maximum acceleration ratio of single core DSP operator acceleration is 16.44. In this method, the scale of computing nodes is expanded from 1067 to 4139, the time required to reach the given termination condition is reduced from 43.02 h to 16.05 h, and the expansion efficiency is 69.1%. Evaluation shows that this method can realize the efficient parallel training of MiniGo on large-scale heterogeneous computing platforms.

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