Mapping-Aware Kernel Partitioning Method for CGRAs Assisted by Deep Learning

Coarse-grained reconfigurable architecture (CGRA) has become a promising candidate for data-intensive computing due to its flexibility and high energy efficiency. CGRA compilers map data flow graphs (DFGs) extracted from applications onto CGRAs, playing a fundamental role in fully exploiting hardware resources for acceleration. Yet the existing compilers are time-demanding and cannot guarantee optimal results due to the traversal search of enormous search spaces brought about by the spatio-temporal flexibility of CGRA structures and the complexity of DFGs. Inspired by the amazing progress in reinforcement learning (RL) and Monte-Carlo tree search (MCTS) for real-world problems, we consider constructing a compiler that can learn from past experiences and comprehensively understand the target DFG and CGRA.

The coarse-grained reconfigurable architecture (C-GRA) is a promising platform that provides both high performance and high power-efficiency. Dataflow graph (DFG) mapping is critical to tap the potentials of CGRAs. Inspired from the great progress made in tree search game using deep neural network, we proposed a frame work for learning convolutional neural network for mapping DFGs onto spatial programmable CGRAs. Considering the mapping process, we present a dual-input neural network capturing the features from both DFGs in applications and Process Element Array (PEA) in CGRA. In order to train the neural network, algorithms are designed to automatically generate a data set from PEA intermediate states of preprocessed DFG. Finally, experimental results demonstrate that our proposed mapping approach is competitive with state-of-the-art DFG mapping algorithms in performance while the compilation time is greatly reduced.

Coarse-grained reconfigurable architectures (CGRAs) present an appealing hardware platform by providing the potential for high computation throughput, scalability, low cost, and energy efficiency. CGRAs consist of an array of function units and register files often organized as a two dimensional grid. The most difficult challenge in deploying CGRAs is compiler scheduling technology that can efficiently map software implementations of compute intensive loops onto the array. Traditional schedulers focus on the placement of operations in time and space. With CGRAs, the challenge of placement is compounded by the need to explicitly route operands from producers to consumers. To systematically attack this problem, we take an edge-centric approach to modulo scheduling that focuses on the routing problem as its primary objective. With edge-centric modulo scheduling (EMS), placement is a by-product of the routing process, and the schedule is developed by routing each edge in the dataflow graph. Routing cost metrics provide the scheduler with a global perspective to guide selection. Experiments on a wide variety of compute-intensive loops from the multimedia domain show that EMS improves throughput by 25% over traditional iterative modulo scheduling, and achieves 98% of the throughput of simulated annealing techniques at a fraction of the compilation time.

Emerging communication technologies, such as 5G and beyond, have introduced diverse requirements that demand high performance and energy efficiency at all levels. Furthermore, the real-time requirements of different services vary significantly — increasing the baseband processor design complexity and demand for flexible hardware platforms. This paper identifies the key characteristics of hardware platforms for baseband processing and describes the existing processing limitations in traditional architectures. In this paper, Coarse-Grained Reconfigurable Architecture (CGRA) is examined as a prospective hardware platform and its characteristic features are highlighted as compared to traditionally employed architectures that make it a suitable candidate for incorporation as a domain-specific accelerator in baseband processing applications. We survey various CGRAs from the last two decades (2004-2023) and analyze their distinct architectural features which can serve as a reference while designing CGRAs for baseband processing applications. Moreover, we investigate the existing challenges toward developing CGRAs for baseband processing and explore their potential solutions. We also provide an overview of the emerging research directions for CGRA and how they can contribute toward the development of advanced baseband processors. Lastly, we highlight a conceptual RISC-V+CGRA framework that can serve as a potential direction toward integrating CGRA in future baseband processing systems.

Coarse-grained reconfigurable architectures (CGRAs) are gaining increasing attention as domain-specific accelerators due to their high flexibility and energy efficiency. These architectures offer a compelling solution for applications that require custom hardware performance while retaining a degree of programmability. However, the design space of CGRAs is inherently vast and complex, presenting significant challenges for architects to explore design choices efficiently and systematically. Existing design space exploration (DSE) methodologies for CGRAs are often time-demanding and struggle to deliver optimal solutions when confronted with high-dimensional and multi-objective design space. Therefore, we consider constructing a CGRA parameter tuning framework called MoDAF. MoDAF initializes the design space using the most representative and diverse samples. It adopts a divide-and-conquer approach, utilizing Monte Carlo Tree Search (MCTS) and space partitioning techniques to dynamically break down the complex design space into more manageable subspaces. A hybrid model handles local fluctuations within each subspace, while a dual sampling algorithm is designed to increase sampling efficiency. MoDAF also incorporates a fast evaluation model to estimate CGRA throughput and area, significantly speeding up the exploration process. Compared with previous approaches, experiments show that our proposed framework reduces the average distance from the reference set by 53.0% and the hypervolume deviation by 64.2%, while also cutting wall time by 57.5%.

With regards to network structured data nowadays, link prediction stands out as a key problem. It has been observed that interactions between the entities act as the basic foundations of many applications in various fields such as chemistry, biology, or social networks. In the previous studies on this subject, most of the approaches used heuristics methods with an evaluation function to find the similarity index between entities, thereby predicting the possibility of links between them. However, heuristics methods are based on assumptions about the existence of associations between entities; thus its shortcoming is that when these assumptions are not accurate, the results of the algorithm would be reduced significantly. Taking those into considerations, in this paper, we propose a method to solve this problem based on deep graph convolutional neural network. Experimental results on paper citation network dataset have shown that particular and this method is promising.KeywordsGraph neural networksDeep graph convolutional neural networkLink predictionPaper citation network

Mobile computing as exemplified by the smart phone has become an integral part of our daily lives. The next generation of these devices will be driven by providing richer user experiences and compelling capabilities: higher definition multimedia, 3D graphics, augmented reality, and voice interfaces. To meet these goals, the core computing capabilities of mobile terminals must be scaled within highly constrained energy budgets. Coarse-grained reconfigurable architectures (CGRAs) are an appealing hardware platform for mobile systems by providing programmability with the potential for high computational throughput, low cost, and energy efficiency. CGRAs are most commonly used for innermost loops that contain an abundance of instruction-level parallelism. Unfortunately, current CGRAs fail to meet future performance requirements due to their inability to scale. Simply increasing the size of the array is too expensive in terms of power and area. In this paper, we first perform a deep analysis of several mobile applications from the domains of multimedia and gaming. We then explore potential solutions in the context of these applications for scaling the array performance in an energy efficient manner: homogeneous versus heterogeneous functionality, interconnect topologies, simple versus complex processing elements, and scalar versus vector memory support.

Coarse-grained reconfigurable architectures (CGRAs) are increasingly employed as domain-specific accelerators due to their efficiency and flexibility. A CGRA typically relies on compilers to perform task scheduling. The longstanding problem of static scheduling is that it suffers from insufficient parallelism in handling irregularities due to over-serialization and workload imbalance, which leads to severe resource underutilization and performance loss. To counteract the limitations of static scheduling in CGRAs, it is essential to exploit dynamic parallelism automatically and manage hardware resources adaptively. However, existing dynamic scheduling mechanisms, e.g., work stealing, often reschedule aggressively for instant performance but sacrifice efficiency, which is unfavorable to CGRAs that emphasize efficiency and fewer reconfigurations. This article proposes an elastic task scheduling scheme that enables lightweight dynamic scheduling in CGRAs. Tasks are rescheduled at runtime according to the classic tagged-token dataflow paradigm to enable dynamic task-level parallelism. Meanwhile, tasks are dynamically resized according to run-time throughputs via duplication, combination, and substitution operators for balanced multitask execution. We implement the elastic task scheduling scheme on a well-known reconfigurable architecture - triggered instruction architecture (TIA). Evaluation on the MachSuite benchmarks shows that the proposed scheme is effective in improving performance and energy efficiency. The average speedup is 2× over the baseline. Also, our design attains a 57 percent improvement in the area-normalized performance and a 49 percent better energy efficiency. Compared with a state-of-the-art dynamic scheduling method, our scheme achieves 1.6× speedup and 1.6× energy efficiency than work-stealing mechanism on the same substrate.

Coarse-grained reconfigurable architecture (CGRA) is a promising accelerator design choice due to its high performance and power efficiency in the computation or data-intensive application domains, such as security, multimedia, digital signal processing, machine learning, and high-performance computing. CGRA consists of coarse-grained processing elements (PEs) and interconnects that determine the architecture flexibility to support different applications and also affect the performance and power efficiency significantly. Although multiple types of interconnects have been proposed, a parameterized unified model is still lacking. In this paper, we propose a flexible and scalable CGRA template with a novel interconnect model that can unify the typical neighbor-to-neighbor, switch-based, and FPGA-like interconnects. Furthermore, we present TRAM, an open-source template-based reconfigurable architecture modeling framework that integrates the Chisel-based CGRA modeling, architecture intermediate representation (IR) and Verilog generation, dataflow graph (DFG) mapping, simulation, and evaluation. The mapping flow contains graph-based placement and routing, critical-path-driven data synchronization, and simulated-annealing-based optimization. We evaluate the impacts of the rich design parameters, which demonstrate the significance of such a flexible template to facilitate architecture optimization. Compared with the related work, TRAM can achieve a 4.1× smaller DFG latency and a faster mapping speed for both the 8×8 and 16×16 CGRAs. Moreover, TRAM is able to attain an extremely high PE utilization of 94.4 % on average by architecture tuning.

Coarse-grained reconfigurable architectures (CGRAs) is one of the suitable devices for IoT (Internet of Things) and edge-computing because of their high energy efficiency and programmability. The CGRAs process a compute-intensive part of an application program (especially a loop part) more efficiently than general purpose processors. CMA (Cool Mega Array) is an energy-conscious CGRA with a task-level reconfiguration instead of a cycle-level one. However, the CMA faces some limitations related to data management because of the aggressive pursuit of power saving. In this paper, we introduce a new CMA architecture VPCMA2 to relax the constraints and to improve energy efficiency. Then, we implement it with a 65-nm process technology to evaluate a hardware overhead due to the improvement. According to the evaluation results, the new design does not influence its maximum operating frequency. Although new functionalities brought about 17% power overhead and 10% area overhead, a remarkable improvement of application mappability and data handling was achieved.

In terms of energy and flexibility, Coarse-Grained Reconfigurable Architectures (CGRA) are proven to be advantageous over fine-grained architectures, massively parallel GPUs and generic CPUs. However the key challenge of programmability is preventing wide-spread adoption. To exploit instruction level parallelism inherent to such architectures, optimal scheduling and mapping of algorithmic kernels is essential. Transforming an input algorithm in the form of a Data Flow Graph (DFG) into a CGRA schedule and mapping configuration is very challenging, due the necessity to consider architectural details such as memory bandwidth requirements, communication patterns, pipelining and heterogeneity to optimally extract maximum performance. In this paper, an algorithm is proposed that employs Force-Directed Scheduling concepts to solve such scheduling and resource minimization problems. Our heuristic extensions are flexible enough for generic heterogeneous CGRAs, allowing to estimate the execution time of an algorithm with different configurations, while maximizing the utilization of available hardware. Beside our experiments, we compare also given CGRA configurations introduced by state-of-the-art mapping algorithms such as EPIMap, achieving optimal resource utilization by our schedule with a reduced overall DFG execution time by 39% on average.

As computation migrates to the edge, energy efficiency is becoming even more critical in the design of electronic devices. Therefore, new applications for the Internet of Things pose a challenge for designers to find the optimal balance between performance and energy consumption. While Coarse Grained Reconfigurable Architectures (CGRA) have been an alternative to provide the required acceleration, they are far from being the most energy-efficient, since their functional units may be underutilized by some applications. In this work, we introduce a novel approach to handle these CGRA resources, which leverages the variable usage of functional units due to the application program phases. By using our new approach and performing power-gating of under-utilized parts of the CGRA, we demonstrate that it is possible to achieve reductions of up to 52.3% in power dissipation and 75% in energy consumption.

Energy efficient configuration unification and compression for CGRAs

Coarse-Grained Reconfigurable Architectures (CGRAs), which provide good trade-offs between performance, hardware/ energy efficiency and flexibility, as well as offer high degree of parallelism, are fast emerging as a competing platform for the high-performance and embedded applications [3]. In this paper, we propose a timing driven approach for generating cycle-accurate high level simulator for CGRA. The simulator is generated from a high-level language describing the CGRA. Experimental results on different architectures and application kernels show that the proposed simulator is \(1.5\times \) to \(4\times \) faster than state-of-the-art RTL simulators.

Autism Spectrum Disorder (ASD) presents significant diagnostic challenges due to its complex, heterogeneous nature. This study explores a novel approach to enhance the accuracy and reliability of ASD diagnosis by integrating resting-state functional magnetic resonance imaging with demographic data (age, gender, and IQ). This study is based on improving the spectral graph convolutional neural network (GCN). It introduces a multi-view attention fusion module to extract useful information from different views. The graph’s edges are informed by demographic data, wherein an edge-building network computes weights grounded in demographic information, thereby bolstering inter-subject correlation. To tackle the challenges of oversmoothing and neighborhood explosion inherent in deep GCNs, this study introduces DropEdge regularization and residual connections, thus augmenting feature diversity and model generalization. The proposed method is trained and evaluated on the ABIDE-I and ABIDE-II datasets. The experimental results underscore the potential of integrating multi-view and multimodal data to advance the diagnostic capabilities of GCNs for ASD.