CNS Core: Small: Budgets, Budgets Everywhere: A Necessity for Safe Real-Time on Multicore

CNS 核心：小：预算，预算无处不在：多核安全实时的必要性

• 批准号: 2151829
• 负责人: James Anderson
• 金额: $ 50万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-15 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2151829&HistoricalAwards=false
• 关键词: CNS; Core; Small; Budgets; Everywhere

Multicore computers are increasingly being used to implement real-time systems. In a real-time system, programs exist that are subject to timing constraints. An automobile is a good example: When a car's brake pedal is depressed, the braking system must react by a certain deadline. Many real-time systems are safety-critical, meaning that failures may have catastrophic consequences, such as loss of life or serious financial repercussions. Automobiles are also a good example of a safety-critical system; while a typical driver may be unaware of it, modern cars contain many computers that run a myriad of programs that perform functions required for steering, braking, engine control, etc. Safety-critical real-time systems typically must undergo a certification process that ensures that important functionality is properly supported. An important part of this process is to validate that deadline requirements are met, i.e., that programs execute "on time." To do this, worst-case execution times (WCETs) of programs should be known. Unfortunately, on today's complex multicore computers, determining accurate WCETs is difficult because the worst-case execution time of a program may occur under rare circumstances and thus be difficult to reproduce. The traditional defense against not knowing WCETs with absolute certainty is to have the operating system (OS) enforce execution budgets; a program's budget is a limit on its execution time that the OS ensures won't be exceeded.While budgets have conventionally been enforced at the program level, in challenging real-time applications of interest today, such enforcement is needed at many levels. For example, in an autonomous vehicle, the overall system is broken into subsystems, where each subsystem provides some separate function, e.g., sensing obstacles in the road, computing a plan to react to obstacles, etc. These subsystems, which may contain many programs each, should be subject to budget enforcement as well. For instance, if the obstacle-sensing subsystem takes too much time, then executing the planning subsystem is pointless. This project is directed at (i) identifying the various levels at which budgets must be enforced in complex multicore real-time applications, (ii) examining the implications for real-time safety certification that arise from making multi-level budget enforcement a first-class concern, and (iii) producing efficient implementations of such enforcement. Addressing these goals will enable safer systems to be developed. In terms of broader impacts, a special emphasis will be placed on outreach to girls and women. Such outreach will include: events involving the Graduate Women in Computer Science (GWiCS) group at UNC, which hosts an annual research symposium targeted toward undergraduate women and other underrepresented minorities; Tar Heel Hack, a hackathon for local middle and high school girls; UNC Computer Science's Girls Who Code Club, which provides local girls in grades 6-12 with a community for learning about computer science; and UNC Computer Science's annual Open House and Science Expo. Further outreach to female students will be done in the context of a computer science club for undergraduate women led by the PI called TOPICS (Talking Over Papers In Computer Science).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

多计算机越来越多地用于实现实时系统。在实时系统中，存在受正时限制的程序。汽车是一个很好的例子：当汽车的刹车踏板凹陷时，制动系统必须在某个截止日期之前做出反应。许多实时系统是至关重要的，这意味着失败可能会带来灾难性的后果，例如生命损失或严重的财务影响。汽车也是安全至关重要系统的一个很好的例子；虽然典型的驱动程序可能不知道它，但现代汽车包含许多计算机，这些计算机运行了多种程序，这些程序执行了转向，制动，发动机控制等所需的功能。关键的至关重要的实时系统通常必须经过认证过程，以确保对重要的功能得到适当支持。该过程的重要部分是验证满足截止日期的要求，即该程序“按时执行”。为此，应该知道程序的最差执行时间（WCET）。不幸的是，在当今复杂的多核算计算机上，确定准确的WCET是困难的，因为程序在极少数情况下可能会发生最差的程序执行时间，因此很难复制。不知道WCET的传统辩护是绝对确定的，就是要使操作系统（OS）执行执行预算；计划的预算是其执行时间的限制，该操作系统确保不会超过其执行时间。虽然在计划级别上执行了预算，但在挑战当今的实时申请时，需要在许多级别上进行这种执行。例如，在自动驾驶汽车中，整个系统被打破到子系统中，每个子系统都提供了一些单独的功能，例如，在道路上遇到障碍，计算对障碍等反应的计划等。这些子系统（可能包含许多程序）也应受到预算执行。例如，如果障碍性子系统需要太多时间，那么执行计划子系统是毫无意义的。该项目针对（i）确定必须在复杂的多项实时应用程序中执行预算的各个级别，（ii）研究对实时安全认证的影响，这是由于使多级预算执法成为一流的关注，以及（iii）生产此类执法的有效实施。解决这些目标将使更安全的系统得以开发。就更广泛的影响而言，将特别强调与女孩和妇女的宣传。此类推广将包括：UNC的涉及计算机科学妇女（GWICS）小组的活动的活动，该小组举办了针对本科妇女和其他代表性不足的少数群体的年度研究研讨会； Tar Heel Hack，是当地中学和高中女孩的黑客马拉松； UNC计算机科学的女孩Who Code Club，该俱乐部为6 - 12年级的当地女孩提供了一个社区，以了解计算机科学；以及UNC计算机科学的年度开放日与科学博览会。将在PI主题（关于计算机科学的论文谈论）领导的计算机科学俱乐部的背景下进行进一步的向女学生进行宣传。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的审查标准来评估的。