arXiv subjects

Steven Colleman

Publications and source records attributed to Steven Colleman.

5 recordsLinked to original sources

arXiv2024

COAC: Cross-layer Optimization of Accelerator Configurability for Efficient CNN Processing

To achieve high accuracy, convolutional neural networks (CNNs) are increasingly growing in complexity and diversity in layer types and topologies. This makes it very challenging to efficiently deploy such networks on custom processor architectures for resource-scarce edge devices. Existing mapping exploration frameworks enable searching for the optimal execution schedules or hardware mappings of individual network layers, by optimizing each layer's spatial (dataflow parallelization) and temporal unrolling (execution order). However, these tools fail to take into account the overhead of supporting different unrolling schemes within a common hardware architecture. Using a fixed unrolling scheme across all layers is also not ideal, as this misses significant opportunities for energy and latency savings from optimizing the mapping of diverse layer types. A balanced approach assesses the right amount of mapping flexibility needed across target neural networks, while taking into account the overhead to support multiple unrollings. This paper, therefore, presents COAC, a cross-layer design space exploration and mapping framework to optimize the flexibility of neural processing architectures by balancing configurability overhead against resulting energy and latency savings for end-to-end inference. COAC does not only provide a systematical analysis of the architectural overhead in function of the supported spatial unrollings, but also builds an automated flow to find the best unrolling combination(s) for efficient end-to-end inference with limited hardware overhead. Results demonstrate that architectures with carefully optimized flexibility can achieve up to 38% EDP (energy-delay-product) savings for a set of six neural networks at the expense of a relative area increase of 9.5%.

eess.SY↗

arXiv2024

Optimizing Layer-Fused Scheduling of Transformer Networks on Multi-accelerator Platforms

The impact of transformer networks is booming, yet, they come with significant computational complexity. It is therefore essential to understand how to optimally map and execute these networks on modern neural processor hardware. So far, literature on transformer scheduling optimization has been focusing on deployment on GPU and specific ASICs. This work enables extensive hardware/mapping exploration by extending the DSE framework Stream towards support for transformers across a wide variety of hardware architectures and different execution schedules. After validation, we explore the optimal schedule for transformer layers/attention heads and investigate whether layer fusion is beneficial to improve latency, energy or memory requirements. Our study shows that the memory requirements for active feature data can be drastically reduced, by adapting the execution schedule based on the size of the input of the attention head.

cs.AR↗

arXiv2024

CMDS: Cross-layer Dataflow Optimization for DNN Accelerators Exploiting Multi-bank Memories

Deep neural networks (DNN) use a wide range of network topologies to achieve high accuracy within diverse applications. This model diversity makes it impossible to identify a single "dataflow" (execution schedule) to perform optimally across all possible layers and network topologies. Several frameworks support the exploration of the best dataflow for a given DNN layer and hardware. However, switching the dataflow from one layer to the next layer within one DNN model can result in hardware inefficiencies stemming from memory data layout mismatch among the layers. Unfortunately, all existing frameworks treat each layer independently and typically model memories as black boxes (one large monolithic wide memory), which ignores the data layout and can not deal with the data layout dependencies of sequential layers. These frameworks are not capable of doing dataflow cross-layer optimization. This work, hence, aims at cross-layer dataflow optimization, taking the data dependency and data layout reshuffling overheads among layers into account. Additionally, we propose to exploit the multibank memories typically present in modern DNN accelerators towards efficiently reshuffling data to support more dataflow at low overhead. These innovations are supported through the Cross-layer Memory-aware Dataflow Scheduler (CMDS). CMDS can model DNN execution energy/latency while considering the different data layout requirements due to the varied optimal dataflow of layers. Compared with the state-of-the-art (SOTA), which performs layer-optimized memory-unaware scheduling, CMDS achieves up to 5.5X energy reduction and 1.35X latency reduction with negligible hardware cost.

cs.AR↗

arXiv2022

Stream: Design Space Exploration of Layer-Fused DNNs on Heterogeneous Dataflow Accelerators

As the landscape of deep neural networks evolves, heterogeneous dataflow accelerators, in the form of multi-core architectures or chiplet-based designs, promise more flexibility and higher inference performance through scalability. So far, these systems exploit the increased parallelism by coarsely mapping a single layer at a time across cores, which incurs frequent costly off-chip memory accesses, or by pipelining batches of inputs, which falls short in meeting the demands of latency-critical applications. To alleviate these bottlenecks, this work explores a new fine-grain mapping paradigm, referred to as layer fusion, on heterogeneous dataflow accelerators through a novel design space exploration framework called Stream. Stream captures a wide variety of heterogeneous dataflow architectures and mapping granularities, and implements a memory and communication-aware latency and energy analysis validated with three distinct state-of-the-art hardware implementations. As such, it facilitates a holistic exploration of architecture and mapping, by strategically allocating the workload through constraint optimization. The findings demonstrate that the integration of layer fusion with heterogeneous dataflow accelerators yields up to 2.2x lower energy-delay product in inference efficiency, addressing both energy consumption and latency concerns. The framework is available open-source at: https://github.com/kuleuven-micas/stream.

cs.AR↗

arXiv2018

Identifying the Best Machine Learning Algorithms for Brain Tumor Segmentation, Progression Assessment, and Overall Survival Prediction in the BRATS Challenge

Gliomas are the most common primary brain malignancies, with different degrees of aggressiveness, variable prognosis and various heterogeneous histologic sub-regions, i.e., peritumoral edematous/invaded tissue, necrotic core, active and non-enhancing core. This intrinsic heterogeneity is also portrayed in their radio-phenotype, as their sub-regions are depicted by varying intensity profiles disseminated across multi-parametric magnetic resonance imaging (mpMRI) scans, reflecting varying biological properties. Their heterogeneous shape, extent, and location are some of the factors that make these tumors difficult to resect, and in some cases inoperable. The amount of resected tumor is a factor also considered in longitudinal scans, when evaluating the apparent tumor for potential diagnosis of progression. Furthermore, there is mounting evidence that accurate segmentation of the various tumor sub-regions can offer the basis for quantitative image analysis towards prediction of patient overall survival. This study assesses the state-of-the-art machine learning (ML) methods used for brain tumor image analysis in mpMRI scans, during the last seven instances of the International Brain Tumor Segmentation (BraTS) challenge, i.e., 2012-2018. Specifically, we focus on i) evaluating segmentations of the various glioma sub-regions in pre-operative mpMRI scans, ii) assessing potential tumor progression by virtue of longitudinal growth of tumor sub-regions, beyond use of the RECIST/RANO criteria, and iii) predicting the overall survival from pre-operative mpMRI scans of patients that underwent gross total resection. Finally, we investigate the challenge of identifying the best ML algorithms for each of these tasks, considering that apart from being diverse on each instance of the challenge, the multi-institutional mpMRI BraTS dataset has also been a continuously evolving/growing dataset.

cs.CV↗