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Cover Article Issue
Towards High-Performance Graph Processing: From a Hardware/Software Co-Design Perspective
Journal of Computer Science and Technology 2024, 39 (2): 245-266
Published: 30 March 2024
Abstract Collect

Graph processing has been widely used in many scenarios, from scientific computing to artificial intelligence. Graph processing exhibits irregular computational parallelism and random memory accesses, unlike traditional workloads. Therefore, running graph processing workloads on conventional architectures (e.g., CPUs and GPUs) often shows a significantly low compute-memory ratio with few performance benefits, which can be, in many cases, even slower than a specialized single-thread graph algorithm. While domain-specific hardware designs are essential for graph processing, it is still challenging to transform the hardware capability to performance boost without coupled software codesigns. This article presents a graph processing ecosystem from hardware to software. We start by introducing a series of hardware accelerators as the foundation of this ecosystem. Subsequently, the codesigned parallel graph systems and their distributed techniques are presented to support graph applications. Finally, we introduce our efforts on novel graph applications and hardware architectures. Extensive results show that various graph applications can be efficiently accelerated in this graph processing ecosystem.

Regular Paper Issue
Evaluating RISC-V Vector Instruction Set Architecture Extension with Computer Vision Workloads
Journal of Computer Science and Technology 2023, 38 (4): 807-820
Published: 06 December 2023
Abstract Collect

Computer vision (CV) algorithms have been extensively used for a myriad of applications nowadays. As the multimedia data are generally well-formatted and regular, it is beneficial to leverage the massive parallel processing power of the underlying platform to improve the performances of CV algorithms. Single Instruction Multiple Data (SIMD) instructions, capable of conducting the same operation on multiple data items in a single instruction, are extensively employed to improve the efficiency of CV algorithms. In this paper, we evaluate the power and effectiveness of RISC-V vector extension (RV-V) on typical CV algorithms, such as Gray Scale, Mean Filter, and Edge Detection. By our examinations, we show that compared with the baseline OpenCV implementation using scalar instructions, the equivalent implementations using the RV-V (version 0.8) can reduce the instruction count of the same CV algorithm up to 24x, when processing the same input images. Whereas, the actual performances improvement measured by the cycle counts is highly related with the specific implementation of the underlying RV-V co-processor. In our evaluation, by using the vector co-processor (with eight execution lanes) of Xuantie C906, vector-version CV algorithms averagely exhibit up to 2.98x performances speedups compared with their scalar counterparts.

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