Proceedings of the 27th International Conference on Real-Time Networks and Systems最新文献_第2页

Fault-tolerant transmission of messages of differing criticalities across a shared communication medium 在共享通信媒介上对不同重要程度的消息进行容错传输

Proceedings of the 27th International Conference on Real-Time Networks and Systems Pub Date : 2019-11-06 DOI: 10.1145/3356401.3356417

Kunal Agrawal, Sanjoy Baruah, A. Burns

{"title":"Fault-tolerant transmission of messages of differing criticalities across a shared communication medium","authors":"Kunal Agrawal, Sanjoy Baruah, A. Burns","doi":"10.1145/3356401.3356417","DOIUrl":"https://doi.org/10.1145/3356401.3356417","url":null,"abstract":"We discuss the motivation behind, and the design and analysis of, an algorithm for synthesizing communication schedules for shared media networks in some safety-critical hard-real-time applications such as autonomous navigation and factory automation. Communication media may be inherently noisy in many such environments, and occasional transmission errors hence inevitable. Therefore it is essential that some degree of fault-tolerance be built into the communication protocol that is used --- in some safety-critical application domains, fault-tolerance requirements may be mandated by statutory certification requirements. Since the severity of the consequences of failing to successfully transmit different messages may be different, we consider a mixed-criticality setting in which the fault-tolerance requirement specification for messages are dependent on their criticality: more critical messages are required to be able to tolerate a larger number of faults. We advocate that communication schedules be \"as static as possible\" in safety-critical applications in order to facilitate verification and validation, and discuss the synthesis of semi-static schedules - schedules that are driven by precomputed lookup tables - with the desired fault-tolerance properties for such applications.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127508968","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

Quantum assignment for QoS-aware AFDX network with deficit round robin 具有qos感知的缺轮循AFDX网络的量子分配

Proceedings of the 27th International Conference on Real-Time Networks and Systems Pub Date : 2019-11-06 DOI: 10.1145/3356401.3356421

Aakash Soni, Jean-Luc Scharbarg, Jérôme Ermont

{"title":"Quantum assignment for QoS-aware AFDX network with deficit round robin","authors":"Aakash Soni, Jean-Luc Scharbarg, Jérôme Ermont","doi":"10.1145/3356401.3356421","DOIUrl":"https://doi.org/10.1145/3356401.3356421","url":null,"abstract":"Avionics Full Duplex switched Ethernet (AFDX) is the de facto standard for the transmission of critical avionics flows. It is a specific switched Ethernet solution based on First-in First-out (FIFO) scheduling. Timing constraints have to be guaranteed for such critical flows. The worst-case traversal time analysis introduces some pessimism, leading to a very lightly loaded network: typically less than 10 % of the bandwidth is used. One solution to improve the utilisation of the network is to introduce Quality of Service (QoS) mechanisms. First, it can decrease worst-case delays for the most constrained avionics flows. Second less/non critical additional flows can be transmitted on the network with bounded impact on avionics ones. Deficit Round Robin (DRR) is such a QoS mechanism and it is envisioned for future avionics networks. An optimised WCTT analysis has been proposed for DRR on AFDX, based on network calculus. With DRR, the flow set is divided into classes and each class is allocated a quantum. In each round, transmissions are managed, based on these quanta. Thus delays are significantly impacted by quanta. The contribution of this paper is to propose an efficient quantum assignment for a set of critical avionics flow classes and at most one additional class with less/non critical flows.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116836164","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: 3

Modeling time-triggered service intermittence in network calculus 网络演算中时间触发业务间歇的建模

Proceedings of the 27th International Conference on Real-Time Networks and Systems Pub Date : 2019-11-06 DOI: 10.1145/3356401.3356411

Jonathan Falk, Frank Dürr, K. Rothermel

{"title":"Modeling time-triggered service intermittence in network calculus","authors":"Jonathan Falk, Frank Dürr, K. Rothermel","doi":"10.1145/3356401.3356411","DOIUrl":"https://doi.org/10.1145/3356401.3356411","url":null,"abstract":"Network elements (e.g., switches), which intermit service, i.e., stop forwarding and transmission of data according to a repeating schedule, can be found in many real-time capable communication networks, e.g., communication networks with TDMA, Ethernet with Time-aware Shapers or low-power wireless networks. The behavior of those network elements depends on the (stationary) properties of the network elements, their schedule, and the current time, as well as the offered traffic load. If a networked real-time system generates traffic flows which are not synchronized to the schedules of the network elements, formal frameworks such as Network Calculus (NC) are highly valuable to derive deterministic guarantees for the communication. In this paper, we show the fundamental implications of modeling time-triggered network elements with service intermittence in NC. We identify two archetypes of network elements with intermittent service, and propose time-variant and time-invariant approaches to derive service curve formulations to model them. We evaluate the differences between time-variant and time-invariant service curves with respect to the overestimation of worst-case backlog and worst-case delay, and we identify schedule properties which influence the tightness of the derived bounds.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122471530","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

Optimal routing and scheduling of complemental flows in converged networks 融合网络中互补流的最优路由与调度

Proceedings of the 27th International Conference on Real-Time Networks and Systems Pub Date : 2019-11-06 DOI: 10.1145/3356401.3356415

Jonathan Falk, Frank Dürr, Steffen Linsenmayer, Stefan Wildhagen, Ben W. Carabelli, K. Rothermel

{"title":"Optimal routing and scheduling of complemental flows in converged networks","authors":"Jonathan Falk, Frank Dürr, Steffen Linsenmayer, Stefan Wildhagen, Ben W. Carabelli, K. Rothermel","doi":"10.1145/3356401.3356415","DOIUrl":"https://doi.org/10.1145/3356401.3356415","url":null,"abstract":"Converged networks support applications with completely different (real-time) requirements. The communication paradigms offered in converged networks are predominantly treated as separate entities from the perspective of traffic engineering, e.g., time-triggered traffic for closed-loop control systems, shaped traffic for multimedia-streaming applications, and best-effort traffic for non-time-critical IT applications. However, there are scenarios where applications benefit from considering time-triggered messages and non-time-triggered messages as complemental components of a single traffic flow. These applications have the property that time-triggered transmissions guarantee basic functionality (e.g., stability of a control system), and additional non-time-triggered transmissions improve the application's performance. We present how to model these so-called complemental traffic flows for this type of application using a traffic metric for the description of the non-time-triggered traffic part. Furthermore, we show that complemental flows are suitable for traffic engineering by presenting two different approaches for the problem of optimized joint routing and scheduling in converged networks with mixed integer linear programming. In our evaluations, we use an exemplary min-max objective for the joint routing and scheduling problem which yields an average reduction of the peak value of the traffic metric by 20-30% over constraint-based approaches.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"240 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134153213","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: 3

Optimal soft real-time semi-partitioned scheduling made simple (and dynamic) 最优软实时半分区调度变得简单(和动态)

Proceedings of the 27th International Conference on Real-Time Networks and Systems Pub Date : 2019-11-06 DOI: 10.1145/3356401.3356402

Clara Hobbs, Zelin Tong, James H. Anderson

{"title":"Optimal soft real-time semi-partitioned scheduling made simple (and dynamic)","authors":"Clara Hobbs, Zelin Tong, James H. Anderson","doi":"10.1145/3356401.3356402","DOIUrl":"https://doi.org/10.1145/3356401.3356402","url":null,"abstract":"Semi-partitioned scheduling is an approach to multiprocessor real-time scheduling where most tasks are fixed to processors, while a small subset of tasks is allowed to migrate. This approach offers reduced overhead compared to global scheduling, and can reduce processor capacity loss compared to partitioned scheduling. Prior work has resulted in a number of semi-partitioned scheduling algorithms, but their correctness typically hinges on a complex intertwining of offline task assignment and online execution. This brittleness has resulted in few proposed semi-partitioned scheduling algorithms that support dynamic task systems, where tasks may join or leave the system at runtime, and few that are optimal in any sense. This paper introduces EDF-sc, the first semi-partitioned scheduling algorithm that is optimal for scheduling (static) soft real-time (SRT) sporadic task systems and allows tasks to dynamically join and leave. The SRT notion of optimality provided by EDF-sc requires deadline tardiness to be bounded for any task system that does not cause over-utilization. In the event that all tasks can be assigned as fixed, EDF-sc behaves exactly as partitioned EDF. Heuristics are provided that give EDF-sc the novel ability to stabilize the workload to approach the partitioned case as tasks join and leave the system.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132065687","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

Impact on credit freeze before gate closing in CBS and GCL integration into TSN 对哥伦比亚广播公司关门前信贷冻结和协鑫整合TSN的影响

Proceedings of the 27th International Conference on Real-Time Networks and Systems Pub Date : 2019-11-06 DOI: 10.1145/3356401.3356412

M. Boyer, Hugo Daigmorte

引用次数: 9

Choosing preemption points to minimize typical running times 选择抢占点以最小化典型运行时间

Proceedings of the 27th International Conference on Real-Time Networks and Systems Pub Date : 2019-11-06 DOI: 10.1145/3356401.3356407

Sanjoy Baruah, N. Fisher

{"title":"Choosing preemption points to minimize typical running times","authors":"Sanjoy Baruah, N. Fisher","doi":"10.1145/3356401.3356407","DOIUrl":"https://doi.org/10.1145/3356401.3356407","url":null,"abstract":"The problem of selecting \"effective preemption points\" in a program --- points in the code at which to permit preemption --- in order to minimize overall running time is considered. Prior solutions that have been proposed for this problem are based on workload models in which worst-case known upper bounds are assumed for the duration needed to perform preemptions at particular points in the code, and of the time needed to non-preemptively execute the code between preemption points. Since these solutions are based on worst-case assumptions, they tend to select effective preemption points in a conservative manner; consequently the overall execution time of the program may be needlessly large under most typical run-time circumstances. We consider a more general workload model in which \"typical\" values, as well as upper bounds, are assumed to be known for the preemption durations and the non-preemptive code-execution durations; given such information, we derive algorithms for the optimal placement of preemption points in a manner that minimizes the typical overall running time (while continuing to guarantee, if needed, upper bounds on the worst-case over-all running time). Both off-line solutions (in which all preemption points are selected prior to run-time) and on-line solutions (where the selection of some of the preemption points is made during run-time and therefore can exploit knowledge of the actual durations of prior preemptions and of the executions of already executed pieces of code) are presented and proved optimal.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"110 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126901054","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: 2