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

{"title":"On the use of supervised machine learning for assessing schedulability: application to ethernet TSN","authors":"Tieu Long Mai, N. Navet, J. Migge","doi":"10.1145/3356401.3356409","DOIUrl":"https://doi.org/10.1145/3356401.3356409","url":null,"abstract":"In this work, we ask if Machine Learning (ML) can provide a viable alternative to conventional schedulability analysis to determine whether a real-time Ethernet network meets a set of timing constraints. Otherwise said, can an algorithm learn what makes it difficult for a system to be feasible and predict whether a configuration will be feasible without executing a schedulability analysis? To get insights into this question, we apply a standard supervised ML technique, k-nearest neighbors (k-NN), and compare its accuracy and running times against precise and approximate schedulability analyses developed in Network-Calculus. The experiments consider different TSN scheduling solutions based on priority levels combined for one of them with traffic shaping. The results obtained on an automotive network topology suggest that k-NN is efficient at predicting the feasibility of realistic TSN networks, with an accuracy ranging from 91.8% to 95.9% depending on the exact TSN scheduling mechanism and a speedup of 190 over schedulability analysis for 106 configurations. Unlike schedulability analysis, ML leads however to a certain rate \"false positives\" (i.e., configurations deemed feasible while they are not). Nonetheless ML-based feasibility assessment techniques offer new trade-offs between accuracy and computation time that are especially interesting in contexts such as design-space exploration where false positives can be tolerated during the exploration process.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"6 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":"132718515","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}

{"title":"Response time analysis of multiframe mixed-criticality systems","authors":"I. Hussain, Muhammad Ali Awan, P. Souto, K. Bletsas, B. Akesson, E. Tovar","doi":"10.1145/3356401.3356405","DOIUrl":"https://doi.org/10.1145/3356401.3356405","url":null,"abstract":"The well-known model of Vestal aims to avoid excessive pessimism in the quantification of the processing requirements of mixed-criticality systems, while still guaranteeing the timeliness of higher-criticality functions. This can bring important savings in system costs, and indirectly help meet size, weight and power constraints. This efficiency is promoted via the use of multiple worst-case execution time (WCET) estimates for the same task, with each such estimate characterised by a confidence associated with a different criticality level. However, even this approach can be very pessimistic when the WCET of successive instances of the same task can vary greatly according to a known pattern, as in MP3 and MPEG codecs or the processing of ADVB video streams. In this paper, we present a schedulability analysis for the multiframe mixed-criticality model, which allows tasks to have multiple, periodically repeating, WCETs in the same mode of operation. Our work extends both the analysis techniques for Static Mixed-Cricality scheduling (SMC) and Adaptive Mixed-Criticality scheduling (AMC), on one hand, and the schedulability analysis for multiframe task systems on the other. Our proposed worst-case response time (WCRT) analysis for multiframe mixed-criticality systems is considerably less pessimistic than applying the SMC, AMC-rtb and AMC-max tests obliviously to the WCET variation patterns. Experimental evaluation with synthetic task sets demonstrates up to 63.8% higher scheduling success ratio (in absolute terms) compared to the best of the frame-oblivious tests.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"51 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":"115508858","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}

{"title":"Optimized trusted execution for hard real-time applications on COTS processors","authors":"Anway Mukherjee, Tanmaya Mishra, Thidapat Chantem, N. Fisher, Ryan M. Gerdes","doi":"10.1145/3356401.3356419","DOIUrl":"https://doi.org/10.1145/3356401.3356419","url":null,"abstract":"While trusted execution environments (TEE) provide industry standard security and isolation, its implementation through secure monitor calls (SMC) attribute to large time overhead and weakened temporal predictability, potentially prohibiting the use of TEE in hard real-time systems. We propose super-TEEs, where multiple trusted execution sections are fused together to amortize TEE execution overhead and improve predictability through minimized I/O traffic and reduced switching between normal mode and TEE mode of execution. Super-TEEs may, however, violate a task's timing requirement and impact the schedulability of the system. We present a technique to enforce the correct timing requirement of a task, along with a sufficient test for schedulability in uniprocessors. We also, discuss ct-RM, a static task assignment and partitioned scheduling algorithm to schedule super-TEEs, alongside other real-time tasks, on multicore systems. Experimental results on a Raspberry Pi 3B, further confirmed by simulations, show that ct-RM outperforms the state-of-the-art technique in terms of usable utilization by 12% on average and up to 27%.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"1 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":"122838405","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}

{"title":"Validating high level simulation results against experimental data and low level simulation: a case study","authors":"D. Griffin, J. Harbin, A. Burns, I. Bate, Robert I. Davis, L. Indrusiak","doi":"10.1145/3356401.3356414","DOIUrl":"https://doi.org/10.1145/3356401.3356414","url":null,"abstract":"Simulation can be considered a necessary evil in the validation of systems, especially when the system under consideration is being prototyped and therefore does not presently exist. This is compounded by the use of high level simulators; on the one hand, high level simulation is efficient, in that it abstracts away many details of the system which are deemed to be not important. This allows for a simpler and faster running simulator, which allows the user to obtain results faster and/or perform more experiments. On the other hand, some of the details abstracted away might turn out to be important, introducing inaccuracies. This paper outlines a framework for the statistical understanding and attribution of the errors produced by a high level simulator when compared against real experiments by means of a low level simulator. This allows the user of a simulator to determine whether or not the inaccuracies are significant, and whether or not the high level simulator requires refinements in its accuracy for the results to be valid. These techniques are illustrated via a case study.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"186 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":"131399924","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}

{"title":"Response time analysis of dataflow applications on a many-core processor with shared-memory and network-on-chip","authors":"Amaury Graillat, Claire Maiza, M. Moy, Pascal Raymond, B. Dinechin","doi":"10.1145/3356401.3356416","DOIUrl":"https://doi.org/10.1145/3356401.3356416","url":null,"abstract":"We consider hard real-time applications running on many-core processor containing several clusters of cores linked by a Network-on-Chip (NoC). Communications are done via shared memory within a cluster and through the NoC for inter-cluster communication. We adopt the time-triggered paradigm, which is well-suited for hard real-time applications, and we consider data-flow applications, where communications are explicit. We extend the AER (Acquisition/Execution/Restitution) execution model to account for all delays and interferences linked to communications, including the interference between the NoC interface and the memory. Indeed, for NoC communications, data is first read from the initiator's local memory, then sent over the NoC, and finally written to the local memory of the target cluster. Read and write accesses to transfer data between local memories may interfere with shared-memory communication inside a cluster, and, as far as we know, previous work did not take these interferences into account. Building on previous work on deterministic network calculus and shared memory interference analysis, our method computes a static, time-triggered schedule for an application mapped on several clusters. This schedule guarantees that deadlines are met, and therefore provides a safe upper bound to the global worst-case response time.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"13 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":"126035411","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}

{"title":"Breaking vs. solving: analysis and routing of real-time networks with cyclic dependencies using network calculus","authors":"A. Finzi, Silviu S. Craciunas","doi":"10.1145/3356401.3356418","DOIUrl":"https://doi.org/10.1145/3356401.3356418","url":null,"abstract":"Distributed real-time systems in the aerospace domain require worst-case end-to-end latency analysis methods to provide certification evidence of the correct temporal behavior of critical traffic classes. One such analysis method is the Network Calculus framework. While the Network Calculus analysis is mature enough to be allowed in certification artefacts, it is only applied in networks where there are no cyclic dependencies between communication flows (so-called feed-forward networks). In general topologies, flows can form cyclic dependencies, making it difficult to prove the determinism of a network. There are two approaches to solve this problem: 1) breaking the dependencies in the routing algorithm to study a feed-forward network; 2) solving, i.e., computing the bounds, in the dependency. In this paper, we review the recent improvements of both methods and do a performance analysis of AFDX and TTEthernet networks to compare their impact on the worst-case delay and backlog bounds. Results show that the best method depends on a number of parameters, such as load and dependency length. Using these results, we propose a new routing methodology resulting in the lowest bounds for networks with cyclic dependencies.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"8 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":"131697424","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}

{"title":"Tightness and computation assessment of worst-case delay bounds in wormhole networks-on-chip","authors":"Frederic Giroudot, A. Mifdaoui","doi":"10.1145/3356401.3356408","DOIUrl":"https://doi.org/10.1145/3356401.3356408","url":null,"abstract":"This paper addresses the problem of worst-case timing analysis in wormhole Networks-On-Chip (NoCs). We consider our previous work [5] for computing maximum delay bounds using Network Calculus, called the Buffer-Aware Worst-case Timing Analysis (BATA). The latter allows the computation of delay bounds for a large panel of wormhole NoCs, e.g., handling priority-sharing, Virtual Channel Sharing and buffer backpressure. In this paper, we provide further insights into the tightness and computation issues of the worst-case delay bounds yielded by BATA. Our assessment shows that the gap between the computed delay bounds and the worst-case simulation results is reasonably small (70% tighness on average). Furthermore, BATA provides good delay bounds for medium-scale configurations within less than one hour. Finally, we evaluate the yielded improvements with BATA for a realistic use-case against a recent state-of-the-art approach. This evaluation shows the applicability of BATA under more general assumptions and the impact of such a feature on the tightness and computation time.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"114 20","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113945578","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}

{"title":"Multiprocessor scheduling of elastic tasks","authors":"James Orr, Sanjoy Baruah","doi":"10.1145/3356401.3356403","DOIUrl":"https://doi.org/10.1145/3356401.3356403","url":null,"abstract":"The elastic task model enables the adaptation of recurrent real-time tasks under uncertain or potentially overloaded conditions. The model was originally defined for sequential tasks executing upon a preemptive uniprocessor platform; it was later extended to include tasks with internal parallelism executing on multiple processors. This paper bridges a gap in the theory of elastic task scheduling by considering the multiprocessor scheduling of sequential tasks (i.e., tasks with no internal parallelism). We define algorithms for scheduling sequential elastic tasks under the global and partitioned paradigms of multiprocessor scheduling, and provide a simulation-based comparison of the different approaches.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"83 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":"125140031","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}

{"title":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","authors":"Jérôme Ermont, Yeqiong Song, C. Gill","doi":"10.1145/3356401","DOIUrl":"https://doi.org/10.1145/3356401","url":null,"abstract":"Message from the Program Chairs \u0000We are delighted to welcome you to the 27th edition of the International Conference on Real-Time Networks and Systems (RTNS), in Toulouse, France. RTNS is a friendly conference with a great sense of community that offers excellent opportunities for collaboration as well as a high-quality technical program. RTNS publishes papers addressing temporal issues in any area of computation and communication, at any level of abstraction, and in any application domain. \u0000This year we received 37 submissions and accepted 20 papers. The reviewing process involved 44 program committee members, who were assisted by 22 additional reviewers. Each submission received at least three reviews. Among the accepted papers, 4 outstanding papers were chosen, which are highlighted in the program, from which a separate committee selected one best paper and one best student paper. \u0000The conference program features a keynote talk giving a view on future challenges for the real-time community by Prof. Marko Bertogna (University of Modena, Italy), an industrial session on real-time challenges in four selected industrial application domains: automotive engine control systems (by Continental AG); automatic air transport (by Thales AVS France); electric smart grid substation automation systems (by SCLE-SFE, Groupe ENGIE); deterministic networking (by Cisco), and 6 technical sessions for accepted papers: analysis and validation; fault-tolerance, security, and data-flow; networking I and II; processor scheduling; and synchronization, preemption, and coordination. The main conference is also again complemented by the Junior Researcher Workshop on Real-Time Computing (JRWRTC), which is now in its 13th successful year. \u0000We would like to thank our many colleagues who have contributed to the success of RTNS 2019. First of all, we thank the Steering Committee for trusting us to manage the technical aspects of the conference. We also owe sincere thanks to all the PC members and reviewers who completed the crucial reviewing and shepherding work for the conference. The conference simply would not have been possible without the significant and sustained efforts of our General Chair, Jerome Ermont (IRIT, ENSEEIHT, France), and the 5 members of the Local Organization Committee, who coordinated all aspects of the conference venue, web site, and the event itself. We also are grateful to the JRWRTC co-Chairs Antonio Paolillo (ULB, Belgium) and Benjamin Rouxel (UVA, Netherlands), and to the 15 members of the Workshop Committee for their efforts. Last but not least, we would like to thank the authors of all submitted papers – by entering your work into the process of review, critique, and possible rejection, even papers that were not accepted have helped to drive the important process of advancement in our field. We know it can be frustrating to have a paper rejected, but we hope that for each paper the reviewing feedback was helpful. Finally, we would like to thank th","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"44 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":"114879403","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}

{"title":"Software-defined wireless mesh networking for reliable and real-time smart city cyber physical applications","authors":"Akram Hakiri, A. Gokhale, Pascal Berthou","doi":"10.1145/3356401.3356406","DOIUrl":"https://doi.org/10.1145/3356401.3356406","url":null,"abstract":"The growing demand for and the diverse mobility patterns of smart devices place an increasing strain on the wireless mesh networks (WMNs) of smart city cyber physical systems (CPS). Realizing reliable and real-time smart city CPS applications is challenging because routing the data among wireless routers using existing routing algorithms that are based on Ad-Hoc and local area network flavors cannot make effective routing decisions due mainly to only local knowledge maintained by an individual router about each of its neighbors, which reflects only a partial visibility of the network. An attractive and more realistic alternative is to adopt Software Defined Networking (SDN), which offers a logically centralized, up-to-date view of the entire network by refactoring the wireless protocols into control and forwarding decisions. This paper presents solutions to overcome key challenges that must first be overcome to realize the potential of SDN in WMNs for smart city applications. Specifically, we describe a novel network architecture that integrates SDN and WMNs to perform network virtualization, routing and network traffic engineering thereby improving the predictability, reliability and the flexibility of the communication network. The benefits of this approach are demonstrated and evaluated for an emulated smart cities use case.","PeriodicalId":322493,"journal":{"name":"Proceedings of the 27th International Conference on Real-Time Networks and Systems","volume":"136 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":"121225765","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}