Awkernel：RTOS 桥接DAG调度理论与面向组件的实时系统实践

中文摘要 AI 辅助

实时有向无环图（DAG）调度为面向组件的实时系统（CORTS）如自动驾驶系统提供了时序分析和效率的严谨基础，然而从理论家和实践者的角度来看仍存在挑战。对于理论家而言，没有操作系统原生支持DAG任务模型；因此算法仅在分析或模拟中评估，忽略了真实硬件的开销。对于实践者而言，当今的CORTS平台（ROS 2和AUTOSAR自适应平台）是为服务组合而非时序可分析性设计的；采用DAG调度研究因此需要大量的代码修改和开发人员纪律。本文提出Awkernel，这是第一个原生支持实时DAG调度研究的开源实时操作系统（RTOS），桥接了DAG调度理论与CORTS实践。对于理论家，Awkernel是一个真实硬件测试平台：它提供了模块化的操作系统原生DAG调度器，便于算法实现，并配有随机工作负载生成器和内置评估指标。对于实践者，Awkernel并非当今平台的完全替代品，而是一个最大化时序可分析性的CORTS平台：其熟悉的发布/订阅模型使移植保持机械性，将每个回调映射到一个子任务。此外，其函数即子任务（FasS）API无需程序员纪律即可强制执行DAG语义（优先级约束），产生与理论DAG模型匹配的应用程序，并直接继承其效率和安全性保证。在树莓派4上，微基准测试确认了微秒级的调度开销；全局最早截止时间优先（GEDF）调度器仅需226行代码；一位实践者仅使用FasS API移植了自动驾驶系统的一部分，无需推理DAG语义。

英文摘要

Real-time directed acyclic graph (DAG) scheduling provides a rigorous basis for timing analysis and efficiency in component-oriented real-time systems (CORTS) such as autonomous driving systems, yet challenges remain from the perspectives of both theorists and practitioners. For theorists, no OS natively supports the DAG task model; algorithms are therefore evaluated only analytically or in simulation, ignoring real-hardware overheads. For practitioners, today's CORTS platforms (ROS~2 and AUTOSAR Adaptive Platform) are designed for service composition rather than timing analyzability; adopting DAG scheduling research therefore demands substantial code changes and developer discipline. This paper proposes Awkernel, the first open-source real-time operating system (RTOS) that natively supports real-time DAG scheduling research, bridging DAG scheduling theory and CORTS practice. For theorists, Awkernel is a real-hardware testbed: it exposes a modular OS-native DAG scheduler for easy algorithm implementation, plus a random workload generator and built-in metrics for evaluation. For practitioners, Awkernel is not a full replacement for today's platforms but a CORTS platform maximizing timing analyzability: its familiar publish/subscribe model keeps porting mechanical, mapping each callback to one subtask. Moreover, its function-as-subtask (FasS) API enforces DAG semantics (precedence constraints) without programmer discipline, yielding applications that match the theoretical DAG model and directly inherit its efficiency and safety guarantees. On a Raspberry Pi~4, microbenchmarks confirm microsecond-level scheduling overheads; a global earliest deadline first (GEDF) scheduler fits in 226~lines; and a practitioner ports part of an autonomous driving system using only the FasS API, without reasoning about DAG semantics.

发表机构

• Graduate School of Science and Engineering, Saitama University（埼玉大学理工学研究科）
• TIER IV, Inc.（TIER IV 公司）
• The University of Tokyo（东京大学）

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