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Accelerating Unstructured Sparse DNNs via Multilevel Partial Sum Reduction and PE Array-Level Load Balancing

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AI
C
Chendong Xia
李强 (Qiang Li)
Z
Zhi Li
李冰 cover
李冰 (Bing Li)
赵慧冬 (Huidong Zhao)
S
Shushan Qiao
DOI:10.1109/TVLSI.2025.3577626delete
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Abstract

Abstract

En 中文
Unstructured pruning introduces significant sparsity in deep neural networks (DNNs), enhancing accelerator hardware efficiency. However, three critical challenges constrain performance gains: 1) complex fetching logic for nonzero (NZ) data pairs; 2) load imbalance across processing elements (PEs); and 3) PE stalls from write-back contention. This brief proposes an energy-efficient accelerator addressing these inefficiencies through three innovations. First, we propose a Cartesian-product output-row-stationary (CPORS) dataflow that inherently matches NZ data pairs by sequentially fetching compressed data. Second, a multilevel partial sum reduction (MLPR) strategy minimizes write-back traffic and converts random PE stalls into manageable load imbalance. Third, a kernel sorting and load scheduling (KSLS) mechanism resolves PE idle/stall and achieves PE array-level load balancing, attaining 76.6% average PE utilization across all sparsity levels. Implemented in 22-nm CMOS, the accelerator delivers <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.85\times $ </tex-math></inline-formula> speedup and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.4\times $ </tex-math></inline-formula> energy efficiency over baseline and achieves 25.8 TOPS/W peak energy efficiency at 90% sparsity.
Keywords:
Accelerator
convolution
deep neural network (DNN)
energy efficiency
load balance
unstructured sparsity

Journal

I
IEEE Transactions on Very Large Scale Integration (VLSI) Systems
IF:
3.1
Papers:
440
Citations:
7.3K

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