Latency awareness in operating systems for massively parallel processors

LAOS研究并发共享内存进程同步中延迟的对策。第一阶段，从而形成预防，namlely建设性的措施，在系统软件开发时间，避免进程延迟演变在运行时。如果单独的预防措施无法提供帮助，第二步的目标是至少避免这些乳管中的强烈抖动。如果即使是那些处理延迟避免的减轻措施也无效，则第三阶段的尝试是在适用的情况下隐藏延迟。分析措施，不断量化或监测，分别处理延迟，并试图通过调度水平和最小化它们不是项目的主题。项目的延续重点是通过所谓的保护部分隐藏延迟。与传统的临界区实现方式不同，保护区不受并发共享内存进程的互斥影响。相反，竞争过程将连续的可行任务留给控制通过临界区的过程。作业按照无等待的同步排队规则排队和服务。一个强制进程遇到一个不活动的保护区时，会激活它并接管队列处理中的领导权。竞争进程总是通过一个受保护的部分，非阻塞和等待自由。然而，根据需要，它们由于事件的条件同步而阻塞，该事件指示将区段不同的计算值分配给某个占位符变量。为了支持受保护的部分，一个等待自由同步操作系统内核的开发提供所需的最低限度的基础系统功能的优先级控制processes.The项目的条件同步源于现有的知识，保护临界区的非顺序程序一般和操作系统程序，特别是。它的基本假设是，通过异步顺序执行的临界区所支持的保护部分，非顺序程序的性能提高，因为增加的并行进程的程度，一方面，并加强缓存的多核处理器在时间和空间上的局部性，另一方面。进程调度策略和进入/退出协议的保护部分之间的具体相互关系的挑战。还受到质疑的是当前和遗留系统在所开发概念和技术的适用性、可移植性和概括性方面的一般关系。

LAOS investigates countermeasures to latencies in the synchronisation of concurrent shared-memory processes. The first stage thereby forms prevention, namlely constructive measures at system-software development time that avert process latencies to evolve at run-time. Where prophylaxis alone cannot help, objective of a second step is to avoid at least strong jitter in those latencies. If even those abatement measures of process-latency avoidance are not effective, attempt of the third stage is to hide latency wherever applicable. Analytical measures that continuously quantify or monitor, respectively, process latencies and try to level and minimise them by means of scheduling are no subject of the project.Emphasis of the project continuation is latency hiding through so called guarded sections. In contrast to the conventional implementation of critical sections, guarded sections are not subject to mutual exclusion of concurrent shared-memory processes. Instead, contending processes leave sequential workably mandates for a process that controls passage through the critical section. The assignments are queued and served following a wait-free synchronised queuing discipline. A mandating process that encounters an inactive guarded section activates it and takes over leadership in queue processing. Contending processes always pass a guarded section non-blocking and wait-free. As needed, they however block due to conditional synchronisation on the event indicating the assignment of a section-distinct computational value to some placeholder variable. In order to support guarded sections, a wait-free synchronised operating-system kernel is developed to provide the required minimal basis of system functions for conditional synchronisation for priority-controlled processes.The project emanates from existing knowledge of protecting critical sections in non-sequential programs in general and operating-system programs in particular. It makes the basic assumption that, through asynchronous sequential execution of critical sections supported by guarded sections, performance of non-sequential programs improves because of increased degree of parallel processes, on the one hand, and strenghtening cache locality of many-core processors in time and space, on the other hand. The specific interrelation between process-scheduling strategies and entry/exit protocols of guarded sections is challenged. Also questioned is the general relationship as to current and legacy systems in terms of applicability, transferability, and generalisation of the developed concepts and techniques.