Making OpenVX Really "Real Time"
Making OpenVX Really "Real Time"
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DOI：
10.1109/rtss.2018.00018
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发表时间：
2018-12
期刊：
影响因子：
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通讯作者：
Ming Yang;Tanya Amert;Kecheng Yang;Nathan Otterness;James H. Anderson;F. D. Smith;Shige Wang
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文献类型：
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作者：
Ming Yang;Tanya Amert;Kecheng Yang;Nathan Otterness;James H. Anderson;F. D. Smith;Shige Wang
OpenVX是最近批准的一个标准，旨在促进实时嵌入式系统中计算机视觉（CV）应用的设计。尽管OpenVX专注于实时，但在验证实时约束时仍存在一些挑战。这些挑战中的许多都源于这样一个事实，即OpenVX只隐式地定义了可扩展实体的任何概念。在OpenVX下，CV应用程序以处理图的形式指定，这些处理图本质上被认为是端到端整体执行的。这种单块执行阻碍了并行性，并可能导致显著的处理能力损失。以前的工作通过将图节点视为可并行实体来部分解决这个问题，但在OpenVX下，这些节点表示相当粗粒度的CV函数，因此可以以这种方式获得的可用并行性非常有限。在本文中，一个更细粒度的方法调度OpenVX图的建议。这种方法旨在实现额外的并行性，并消除程序在CPU和图形处理单元（GPU）上执行时出现的与可扩展性相关的处理容量损失。这种新方法的响应时间分析，并通过涉及实际CV应用的案例研究评估其疗效。
OpenVX is a recently ratified standard that was expressly proposed to facilitate the design of computer-vision (CV) applications used in real-time embedded systems. Despite its real-time focus, OpenVX presents several challenges when validating real-time constraints. Many of these challenges are rooted in the fact that OpenVX only implicitly defines any notion of a schedulable entity. Under OpenVX, CV applications are specified in the form of processing graphs that are inherently considered to execute monolithically end-to-end. This monolithic execution hinders parallelism and can lead to significant processing-capacity loss. Prior work partially addressed this problem by treating graph nodes as schedulable entities, but under OpenVX, these nodes represent rather coarse-grained CV functions, so the available parallelism that can be obtained in this way is quite limited. In this paper, a much more fine-grained approach for scheduling OpenVX graphs is proposed. This approach was designed to enable additional parallelism and to eliminate schedulability-related processing-capacity loss that arises when programs execute on both CPUs and graphics processing units (GPUs). Response-time analysis for this new approach is presented and its efficacy is evaluated via a case study involving an actual CV application.