Power-Aware Critical Sections

功率感知关键部分

• 批准号: 265905942
• 负责人: Professor Dr.-Ing. Wolfgang Schröder-Preikschat
• 金额: --
• 依托单位: Lehrstuhl für Informatik 4: Verteilte Systeme und Betriebssysteme
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/265905942?language=en
• 关键词: Power; Aware; Critical; Sections

Race conditions of concurrent processes within a computing system may cause partly inexplicable phenomena or even defective run-time behaviour. Reason are critical sections in non-sequential programs. Solutions for the protection of critical sections generally are facing a multi-dimensional problem space: (1) processor-local interrupts, (2) shared-memory multi/many-core multiprocessors with (2a) coherent or (2b) incoherent caches, (3) distributed-memory systems with global address space, (4) interference with process management of the operating system. Thereby, the protection method makes pessimistic or optimistic assumptions regarding the occurrence of access contention.The number of contending processes depends on the use case and has a large impact on the effectiveness of their coordination at all levels of a computing system. Overhead, scalability, and dedication of the protective function thereby constitute decisive performance-affecting factors. This influencing quantity not only accounts for varying process run-times but also different energy uses. The former results in noise or jitter in the program flow: non-functional properties that are especially problematic for highly parallel or real-time dependent processes. In contrast, the later has economical importance as well as ecological consequences on the one hand and is tangent to the boundary of scalability of many-core processors (dark silicon) on the other hand.Subject to the structural complexity of a critical section and its sensitivity to contention, a trade-off becomes apparent that shall be tackled in the project by means of analytical and constructive measures. Objects of investigation are own special-purpose operating systems, which were designed primarily for the support of parallel and partly also real-time dependent data processing, and Linux. Goal is the provision (a) of a software infrastructure for load-dependent and---by the program sections---self-organized change of protection against crucial race condition of concurrent processes as well as (b) of tools for preparation, characterisation, and capturing of those sections. Hotspots caused by increased process activity and becoming manifested in energy-use and temperature rise shall be avoided or attenuated on demand or anticipatory by a section-specific dispatch policy. The overhead induced by the particular dispatch policy slips in the weighting to dynamic reconfiguration of a critical section for undertaking a change only in case that real practical gain compared to the original solution can be expected. Before-after comparisons based on the investigated operating systems shall demonstrate the effectivity of the approach developed.

计算系统中并发进程的竞争条件可能会导致部分无法解释的现象，甚至是有缺陷的运行时行为。原因是非顺序程序中的关键部分。保护临界区的解决方案通常面临多维问题空间：（1）处理器本地中断，（2）具有（2a）相干或（2b）非相干高速缓存的共享存储器多/众核多处理器，（3）具有全局地址空间的分布式存储器系统，（4）与操作系统的进程管理的干扰。因此，该保护方法对访问竞争的发生做出悲观或乐观的假设，竞争进程的数量取决于用例，并且对它们在计算系统的所有级别上的协调的有效性有很大的影响。因此，保护功能的开销、可扩展性和专用性构成了决定性的性能影响因素。这种影响量不仅说明了不同的过程运行时间，而且还说明了不同的能量使用。前者导致程序流中的噪声或抖动：对于高度并行或实时依赖的进程来说，非功能性属性尤其成问题。相比之下，后者一方面具有经济重要性，另一方面也具有生态后果，并且与众核处理器（暗硅）的可扩展性边界相切。由于关键部分的结构复杂性及其对竞争的敏感性，权衡变得明显，应通过分析和建设性措施在项目中解决。调查的对象是自己的专用操作系统，这主要是为了支持并行和部分实时相关的数据处理，和Linux。目标是提供（a）一个软件基础设施，用于负载相关和--由程序部分--自组织的保护变化，以防止并发进程的关键竞争条件，以及（B）用于准备，表征和捕获这些部分的工具。因工艺活动增加而引起的热点以及能源使用和温度升高所表现出来的热点，应根据需要或通过特定部门的调度政策进行预防或减弱。由特定分派策略引起的开销在权重中滑动到临界区段的动态重新配置，以仅在与原始解决方案相比可以预期真实的实际增益的情况下进行改变。基于所研究操作系统的前后比较应证明所开发方法的有效性。