Proceedings of the 24th International Conference on Real-Time Networks and Systems最新文献_第4页

MILP-based Deadline Assignment for End-to-End Flows in Distributed Real-Time Systems 分布式实时系统中基于milp的端到端流截止时间分配

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997498

Bo Peng, N. Fisher, Thidapat Chantem

{"title":"MILP-based Deadline Assignment for End-to-End Flows in Distributed Real-Time Systems","authors":"Bo Peng, N. Fisher, Thidapat Chantem","doi":"10.1145/2997465.2997498","DOIUrl":"https://doi.org/10.1145/2997465.2997498","url":null,"abstract":"End-to-end flows, which have a set of chainlike subtasks, are widely used in distributed real-time systems. For instance, multimedia and automative applications require that subtasks finish executing on a chain of processors before their end-to-end deadlines. The scheduling of such chained subtasks decides the schedulability of a distributed realtime system. Since the subtask priority assignment problem is NP-hard in general, most heuristics are presented to schedule end-to-end flows in two separate steps. The first step calculates intermediate relative deadlines for frames, and the second step makes scheduling decisions under EDF scheduling. Because the quality of the priority assignment of subtasks will directly affect the schedulability of the distributed systems, the two separate steps may cause pessimism in schedulability analysis. To reduce potential pessimism, we combine the two steps in our novel dGMF-PA (distributed generalized multiframe tasks with parameter adaption) model. We present an algorithm based on mixed-integer linear programming for optimally selecting frame relative deadlines in the dGMF-PA model. An approximation algorithm is also proposed to reduce computational running time. Our approximation algorithm has a tunable speed-up factor of 1 + ϵ where ϵ can be arbitrarily small, with respect to the exact schedulability test of dGMF-PA tasks under EDF scheduling. Extensive experiments have shown that our approximation algorithm (which is a sufficient schedulability test) can schedule at most 44 % more than HOSPA, an existing state-of-the-art algorithm.","PeriodicalId":245345,"journal":{"name":"Proceedings of the 24th International Conference on Real-Time Networks and Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130394548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

A Software Managed Stack Cache for Real-Time Systems 实时系统的软件管理堆栈缓存

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997488

Alexander Jordan, Sahar Abbaspour, Martin Schoeberl

{"title":"A Software Managed Stack Cache for Real-Time Systems","authors":"Alexander Jordan, Sahar Abbaspour, Martin Schoeberl","doi":"10.1145/2997465.2997488","DOIUrl":"https://doi.org/10.1145/2997465.2997488","url":null,"abstract":"In a real-time system, the use of a scratchpad memory can mitigate the difficulties related to analyzing data caches, whose behavior is inherently hard to predict. We propose to use a scratchpad memory for stack allocated data. While statically allocating stack frames for individual functions to scratchpad memory regions aids predictability, it is limited to non-recursive programs and static allocation has to take different calling contexts into account. Using a stack cache that dynamically spills data to and fills data from external memory avoids these problems, while its simple design allows for efficiently deriving worst-case bounds through static analysis. In this paper we present the design and implementation of software managed caching of stack allocated data in a scratchpad memory. We demonstrate a compiler-aided implementation of a stack cache using the LLVM compiler framework and report on its efficiency. Our evaluation encompasses stack management overhead and impact on worst-case execution time analysis. The state-of-the-art worst-case execution time analysis tool aiT is able to correctly classify all stack cache accesses as accesses to the scratchpad memory.","PeriodicalId":245345,"journal":{"name":"Proceedings of the 24th International Conference on Real-Time Networks and Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134033244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Efficient Algorithm for Jitter Minimization in Time-Triggered Periodic Mixed-Criticality Message Scheduling Problem 时间触发周期混合临界消息调度问题中抖动最小化的有效算法

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997481

A. Novák, P. Šůcha, Z. Hanzálek

{"title":"Efficient Algorithm for Jitter Minimization in Time-Triggered Periodic Mixed-Criticality Message Scheduling Problem","authors":"A. Novák, P. Šůcha, Z. Hanzálek","doi":"10.1145/2997465.2997481","DOIUrl":"https://doi.org/10.1145/2997465.2997481","url":null,"abstract":"The current research in real-time scheduling focuses mostly on the certification of functionalities with respect to safety requirements under conservative assumptions or to achieve efficient resource utilization but with optimistic assumptions. With growing system complexity, the safety certification is becoming hard, especially in event-triggered environments. In time-triggered environments, the network nodes are synchronized by clocks and follow a static schedule hence they are easily certifiable. However, the time-triggered paradigm has two disadvantages. The first one is its general non-flexibility (e.g. message retransmission, efficient resource usage) and the second one is the need for an efficient scheduling algorithm producing the schedule. In this paper, we propose a solution to both of these issues. To address the first disadvantage, we propose a method for non-preemptive message retransmission in time-triggered environments while preserving the efficient use of resources. Based on the message criticality we allow a certain number of retransmissions. The observed prolongation of the processing time of a highly critical message is compensated by skipping transmission of less critical messages. Static schedules then contain all alternatives caused by the retransmissions that can occur during a run time execution. Schedules conform with certification requirements imposed on the highly critical messages while preserving the efficient use of resources. To address the second disadvantage, we propose a novel heuristic scheduling algorithm with an unscheduling step for solving large instances of periodic message scheduling problem. The message periodicity is assumed to be a power of two and the objective is to minimize the maximal jitter. The efficiency of the approach is demonstrated on problem instances with up to 2000 messages.","PeriodicalId":245345,"journal":{"name":"Proceedings of the 24th International Conference on Real-Time Networks and Systems","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124288602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

On Task Period Assignment in Multiprocessor Real-Time Control Systems 多处理器实时控制系统任务周期分配研究

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997469

A. Roy, Hakan Aydin, Dakai Zhu

引用次数: 0

Proceedings of the 24th International Conference on Real-Time Networks and Systems 第24届实时网络与系统国际会议论文集

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 1900-01-01 DOI: 10.1145/2997465

引用次数: 0