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Sparsity 2: Systems

Ballroom C

Moderator: Tushar Krishna


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Ballroom B - Position 19
Efficient GPU Kernels for N:M-Sparse Weights in Deep Learning

Bin Lin · Ningxin Zheng · Lei Wang · Shijie Cao · Lingxiao Ma · Quanlu Zhang · Yi Zhu · Ting Cao · Jilong Xue · Yuqing Yang · Fan Yang

N:M sparsity is becoming increasingly popular due to its promise to achieve both high model accuracy and computational efficiency for deep learning. However, the real-world benefit of N:M sparsity is limited as there is a lack of dedicated GPU kernel implementations for general N:M sparsity with various sparsity ratios. In this work, we present nmSPARSE, a library of efficient GPU kernels for two fundamental operations in neural networks with N:M sparse weights: sparse matrix-vector multiplication (SpMV) and sparse matrix-matrix multiplication (SpMM). By leveraging the intrinsic balance characteristic of N:M sparsity, nmSPARSE kernels rearrange irregular computation and scattered memory accesses in sparse matrix multiplication into hardware-aligned regular computation and conflict-free memory accesses at runtime. Evaluated on NVIDIA A100 GPU, nmSPARSE kernels achieve up to 5.2× speedup on SpMV and 6.0× speedup on SpMM over the fastest baseline. End-to-end studies on transformer models demonstrate that using nmSPARSE outperforms other baselines.

Ballroom B - Position 20
Unified Convolution Framework: A compiler-based approach to support sparse convolutions

Jaeyeon Won · Changwan Hong · Charith Mendis · Joel Emer · Saman Amarasinghe

This paper introduces a Unified Convolution Framework (UCF) that incorporates various existing sparse convolutions in a unified abstraction. This work is in contrast to the common library-based approach that requires much engineering effort because each different sparse convolution must be implemented separately. Instead, it employs a tensor compiler approach that can flexibly explore convolutions with various program transformations; however, no compiler can currently support various sparse convolutions flexibly to our knowledge. In particular, the Tensor Algebra Compiler (TACO) can support a variety of sparse formats but cannot declare convolutions because a tensor cannot be accessed by a linear combination of index variables. We extend TACO's Einsum language to support an affine index expression to declare a convolution. Our method is also compatible with TACO's format and scheduling language, enabling various sparse convolution implementations to be explored. Our experimental results demonstrate that TACO-UCF achieves 1.32× and 8.3× average speedups on a filter sparse convolution and a submanifold sparse convolution, respectively, over state-of-the-art libraries on CPU. TACO-UCF on GPU outperforms the state-of-the-art GPU library on filter sparse convolution of ResNet50 by an average of 1.47× at 80% sparsity. We also demonstrate TACO-UCF outperforms on a neighbor retrieval of a submanifold sparse convolution by an average of 2.55× and 3.34× over MinkowskiEngine and TorchSparse on GPU, respectively.

Ballroom B - Position 21
Exploiting Hardware Utilization and Adaptive Dataflow for Efficient Sparse Convolution in 3D Point Clouds

Ke Hong · Zhongming Yu · Guohao Dai · Xinhao Yang · Yaoxiu Lian · 泽浩 刘 · Ningyi Xu · Yu Wang

Sparse convolution is the key operator in widely-used 3D point cloud networks. However, due to the high sparsity of voxelized input point cloud data, three main challenges need to be solved for efficient sparse convolution in current 3D point cloud engines: (1) Memory under-utilization: the mapping information from input data to weight parameters of 3D point cloud networks is sparse, leading to up to 79.97% redundant memory access and under-utilized memory space; (2) Computation under-utilization: previous FGMS (Fused Gather-Matrix-Multiplication-Scatter) operations in sparse convolution are executed sequentially, leading to a GPU computation utilization of only 22.84%; (3) Input dynamics: a single and static dataflow in the current point cloud engines cannot always achieve the best performance on different input point cloud data.To tackle these challenges, we propose PCEngine, an efficient sparse convolution engine for voxel-based 3D point cloud networks. PCEngine proposes a novel coded-CSR (Compress Sparse Row) format to represent the mapping information without redundancy. PCEngine also introduces the indicator-assisted segmented FGMS fusion scheme to fully utilize the computation resources on GPU hardware. PCEngine further deploys a heuristic adaptive dataflow for input dynamics. Extensive experimental results show that, PCEngine achieves 1.81× and 1.64× speedup on average for sparse convolution operation and end-to-end point cloud networks, respectively.

Ballroom B - Position 22
Sparsity-Aware Memory Interface Architecture using Stacked XORNet Compression for Accelerating Pruned-DNN Models

Younghoon Byun · Seungsik Moon · Baeseong Park · Se Jung Kwon · Dongsoo Lee · Gunho Park · Eunji Yoo · Jung Gyu Min · Youngjoo Lee

This paper presents a new algorithm-hardware co-optimization approach that maximizes memory bandwidth utilization even for the pruned deep neural network (DNN) models.Targeting the well-known model compression approaches, for the first time, we carefully investigate the memory interface overheads caused by the irregular data accessing patterns.Then, the sparsity-aware memory interface architecture is newly developed to regularly access all the data of pruned-DNN models stored with the state-of-the-art XORNet compression.Moreover, we introduce the novel stacked XORNet solution for minimizing the number of data imbalances, remarkably relaxing the interface costs without slowing the effective memory bandwidth.As a result, experimental results show that our co-optimized interface architecture can achieve almost the ideal model-accessing speed with reasonable hardware overheads, successfully allowing the high-speed pruned-DNN inference scenarios.