Proceedings of the 24th International Conference on Real-Time Networks and Systems最新文献_第3页

Supporting Suspension-based Locking Mechanisms for Real-Time Networks-on-chip 支持基于挂起的实时片上网络锁定机制

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997466

Adam Kostrzewa, Sebastian Tobuschat, Selma Saidi, R. Ernst

{"title":"Supporting Suspension-based Locking Mechanisms for Real-Time Networks-on-chip","authors":"Adam Kostrzewa, Sebastian Tobuschat, Selma Saidi, R. Ernst","doi":"10.1145/2997465.2997466","DOIUrl":"https://doi.org/10.1145/2997465.2997466","url":null,"abstract":"In the majority of safety critical systems, suspension-based locking protocols e.g. MPCP, OMLP, FMLP are used to efficiently and safely coordinate accesses to shared resources. However, existing architectures do not support such arbitration for Networks-on-Chip (NoCs) although they must resolve conflicts between concurrent transmissions. Enabling suspensions requires not only predictable transmission latencies but also to provide feedback about the global state of the interconnect which is difficult in NoCs where arbitration is done locally and independently in routers. This leads to pessimistic formal guarantees, decreased utilization and unfulfilled design requirements as network blocking unnecessarily propagates to other tasks scheduled on cores. In this work, we evaluate existing NoC architectures and propose extensions allowing to benefit from real-time tasks multithreading to increase performance while achieving predictability. Consequently, we describe how to improve the processor's utilization and more importantly, how to consistently reach lower worst case latencies for other tasks running in the system. We demonstrate the effectiveness of our approach using formal analysis and scenario-based simulation results.","PeriodicalId":245345,"journal":{"name":"Proceedings of the 24th International Conference on Real-Time Networks and Systems","volume":"21 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":"133825207","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

Time-sensitive Software-defined Network (TSSDN) for Real-time Applications 实时应用的时间敏感软件定义网络(TSSDN)

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997487

N. Nayak, Frank Dürr, K. Rothermel

{"title":"Time-sensitive Software-defined Network (TSSDN) for Real-time Applications","authors":"N. Nayak, Frank Dürr, K. Rothermel","doi":"10.1145/2997465.2997487","DOIUrl":"https://doi.org/10.1145/2997465.2997487","url":null,"abstract":"Cyber-physical systems (CPS), like the ones used in industrial automation systems, are highly time-sensitive applications demanding zero packet losses along with stringent real-time guarantees like bounded latency and jitter from the underlying network for communication. With the proliferation of IEEE 802.3 and IP networks, there is a desire to use these networks instead of the currently used field-buses for time-sensitive applications. However, these networking technologies, which originally were designed to provide best effort communication services, lack mechanisms for providing real-time guarantees. In this paper, we present Time-Sensitive Software-Defined Networks (TSSDN), which provide real-time guarantees for the time-triggered traffic in time-sensitive systems while also transporting non-time-sensitive traffic. TSSDN provides these guarantees by bounding the non-deterministic queuing delays for time-sensitive traffic. To this end, it exploits the logical centralization paradigm of software-defined networking to compute a transmission schedule for time-sensitive traffic initiated by the end systems based on a global view. In particular, we present various Integer Linear Program (ILP) formulations that solve the combined problem of routing and scheduling time-triggered traffic. Moreover, we show that end systems can comply with a given schedule with high precision using user-space packet processing frameworks. Our evaluations show that TSSDN has deterministic end-to-end delays (≤ 14 μs on our benchmark topology) with low and bounded jitter (≤ 7 μs).","PeriodicalId":245345,"journal":{"name":"Proceedings of the 24th International Conference on Real-Time Networks and Systems","volume":"10 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":"132198716","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: 103

State-based Communication on Time-predictable Multicore Processors 时间可预测多核处理器中基于状态的通信

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997480

R. B. Sorensen, Martin Schoeberl, J. Sparsø

引用次数: 0

No-wait Packet Scheduling for IEEE Time-sensitive Networks (TSN) IEEE时间敏感网络(TSN)的无等待分组调度

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997494

Frank Dürr, N. Nayak

{"title":"No-wait Packet Scheduling for IEEE Time-sensitive Networks (TSN)","authors":"Frank Dürr, N. Nayak","doi":"10.1145/2997465.2997494","DOIUrl":"https://doi.org/10.1145/2997465.2997494","url":null,"abstract":"The IEEE Time-sensitive Networking (TSN) Task Group has recently standardized enhancements for IEEE 802.3 networks for enabling it to transport time-triggered traffic (aka scheduled traffic) providing them with stringent bounds on network delay and jitter while also transporting best-effort traffic. These enhancements primarily include dedicating one queue per port of the switch for scheduled traffic along with a programmable gating mechanism that dictates which of the queues are to be considered for transmission. While the IEEE 802.1Qbv standards define these mechanisms to handle scheduled traffic, it stops short of specifying algorithms to compute fine-grained link schedules for the streams of scheduled traffic. Further, the mechanisms in TSN require creation of so-called guard bands to isolate scheduled traffic from the best-effort traffic. These guard bands may potentially result in bandwidth wastage, and hence schedules with lower number of guard bands are preferred. In this paper, we introduce the No-wait Packet Scheduling Problem (NW-PSP) for modelling the scheduling in IEEE Time-sensitive Networks and map it to the No-wait Job-shop Scheduling Problem (NW-JSP), a well-known problem from the field of operational research. In particular, we present a Tabu search algorithm for efficient computing of schedules and a schedule compression technique to reduce number of guard bands in schedule. Our evaluations show that our Tabu search algorithm can compute near-optimal schedules for over 1500 flows and the subsequent schedule compression reduces the number of guard bands on an average by 24%.","PeriodicalId":245345,"journal":{"name":"Proceedings of the 24th International Conference on Real-Time Networks and Systems","volume":"50 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":"123484113","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: 203

Uniprocessor Scheduling Strategies for Self-Suspending Task Systems 自挂起任务系统的单处理器调度策略

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997497

G. V. D. Brüggen, Wen-Hung Huang, Jian-Jia Chen, Cong Liu

{"title":"Uniprocessor Scheduling Strategies for Self-Suspending Task Systems","authors":"G. V. D. Brüggen, Wen-Hung Huang, Jian-Jia Chen, Cong Liu","doi":"10.1145/2997465.2997497","DOIUrl":"https://doi.org/10.1145/2997465.2997497","url":null,"abstract":"We study uniprocessor scheduling for hard real-time self-suspending task systems where each task may contain a single self-suspension interval. We focus on improving state-of-the-art fixed-relative-deadline (FRD) scheduling approaches, where an FRD scheduler assigns a separate relative deadline to each computation segment of a task. Then, FRD schedules different computation segments by using the earliest-deadline first (EDF) scheduling policy, based on the assigned deadlines for the computation segments. Our proposed algorithm, Shortest Execution Interval First Deadline Assignment (SEIFDA), greedily assigns the relative deadlines of the computation segments, starting with the task with the smallest execution interval length, i.e., the period minus the self-suspension time. We show that any reasonable deadline assignment under this strategy has a speedup factor of 3. Moreover, we present how to approximate the schedulability test and a generalized mixed integer linear programming (MILP) that can be formulated based on the tolerable loss in the schedulability test defined by the users. We show by both analysis and experiments that through designing smarter relative deadline assignment policies, the resulting FRD scheduling algorithms yield significantly better performance than existing schedulers for such task systems.","PeriodicalId":245345,"journal":{"name":"Proceedings of the 24th International Conference on Real-Time Networks and Systems","volume":"55 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":"125020445","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: 19

Preemptive scheduling of dependent periodic tasks modeled by synchronous dataflow graphs 基于同步数据流图的依赖周期任务抢占调度

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997474

Enagnon Cédric Klikpo, Alix Munier Kordon

{"title":"Preemptive scheduling of dependent periodic tasks modeled by synchronous dataflow graphs","authors":"Enagnon Cédric Klikpo, Alix Munier Kordon","doi":"10.1145/2997465.2997474","DOIUrl":"https://doi.org/10.1145/2997465.2997474","url":null,"abstract":"Advanced features in modern cars have increased the criticality level of embedded applications in automotive. These applications are generally composed of several communicating functions, for which a deterministic data exchanges is crucial. In the industry, applications are designed with high level models such as Matlab/Simulink. They are implemented on an AUTOSAR platform, where they are scheduled with a fixed-priority based Operating System (OS). However, AUTOSAR OS does not directly provide support for deterministic dataflow implementation. In this paper, we present an approach to implement a deterministic dataflow of dependent periodic tasks on preemptive fixed-priority based uniprocessor. We consider a multi-periodic system consisting in several dependent realtime tasks modeled by a Synchronous Dataflow Graph. We use the scheduling of the graph to make the dependent tasks set independent. This permits to insure a deterministic dataflow without requiring synchronization mechanisms. In addition, it allows to use the existing scheduling policies for independent tasks. We propose several heuristics which find a scheduling solution in 76 percent of cases and provide a fast method to deal with dependencies in multi-periodic systems.","PeriodicalId":245345,"journal":{"name":"Proceedings of the 24th International Conference on Real-Time Networks and Systems","volume":"14 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":"127725851","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: 7

Adaptive Fair Scheduler: Fairness in Presence of Disturbances 自适应公平调度:存在干扰的公平性

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997468

Enrico Bini

引用次数: 3

Quantifying Energy Consumption for Practical Fork-Join Parallelism on an Embedded Real-Time Operating System 嵌入式实时操作系统中实用Fork-Join并行性的能耗量化

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997473

Antonio Paolillo, Paul Rodríguez, Nikita Veshchikov, J. Goossens, B. Rodriguez

引用次数: 17

Scheduling Constrained-Deadline Parallel Tasks on Two-type Heterogeneous Multiprocessors 两类异构多处理器上约束期限并行任务的调度

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997482

Björn Andersson, Gurulingesh Raravi

{"title":"Scheduling Constrained-Deadline Parallel Tasks on Two-type Heterogeneous Multiprocessors","authors":"Björn Andersson, Gurulingesh Raravi","doi":"10.1145/2997465.2997482","DOIUrl":"https://doi.org/10.1145/2997465.2997482","url":null,"abstract":"Consider the problem of scheduling a taskset on a multiprocessor to meet all deadlines. Assume constrained-deadline sporadic tasks and stage-parallelism (i.e., a task comprises one or more stages with a stage comprising one or more segments so that segments in the same stage are allowed to execute in parallel and a segment is allowed to execute only if all segments of the previous stage have finished). Also assume a two-type heterogeneous multiprocessor platform (i.e., there are processors of two types, type-1 and type-2, and for each task, there is a specification of its execution speed on a type-1 processor and on a type-2 processor) and intra-type migration (i.e., a job can migrate between processors of the same type but for a task, all jobs of this task must execute on the same processor type). We present an algorithm for this problem; it assigns each task to a processor type and then schedules tasks on processors of each type with global-Earliest-Deadline-First. It has pseudo-polynomial time complexity and speedup bound at most 5. We also present a variant of this algorithm; it has the same time complexity and same speedup bound but has better average-case performance. We evaluate both algorithms on randomly-generated systems with up to 256 tasks and 256 processors and find that for most systems the algorithms took at most 1 second and they never took more than 42 seconds to finish. Also, for almost 100% of the systems, the latter algorithm succeeds if given processors twice faster than the speed needed to satisfy a necessary feasibility test (hence the algorithm behaves almost as if the speedup bound is two). This is the first work on scheduling parallel real-time tasks on a heterogeneous multiprocessor with provably good performance.","PeriodicalId":245345,"journal":{"name":"Proceedings of the 24th International Conference on Real-Time Networks and Systems","volume":"29 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":"134185079","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: 5

Improving the Schedulability of Mixed Criticality Cyclic Executives via Limited Task Splitting 通过有限任务分割提高混合临界循环执行器的可调度性

Proceedings of the 24th International Conference on Real-Time Networks and Systems Pub Date : 2016-10-19 DOI: 10.1145/2997465.2997492

Tom Fleming, Sanjoy Baruah, A. Burns

{"title":"Improving the Schedulability of Mixed Criticality Cyclic Executives via Limited Task Splitting","authors":"Tom Fleming, Sanjoy Baruah, A. Burns","doi":"10.1145/2997465.2997492","DOIUrl":"https://doi.org/10.1145/2997465.2997492","url":null,"abstract":"Mixed Criticality workloads present a challenging paradigm which requires equal consideration of functional separation and efficient platform usage. As more powerful platforms become available the consolidation of previously federated functionality becomes highly desirable. Such platforms are becoming increasingly multi-core in nature bringing challenges in addition to those of isolation and utilisation. Cyclic Executives (CE) are used extensively in industry to schedule highly critical functionality in a manner which aids certification. The CE paradigm may be applied to the mixed criticality case making use of a number of features to ensure the sufficient separation of different levels of criticality. While previous work has considered the separation of criticality levels, this work focuses on providing high system utilisation. One of the significant challenges of such an implementation is the allocation of work (tasks) to minor cycles and cores. This work considers such an allocation problem and presents a means of testing schedulability using Linear Programming (LP) tools. Toward the aim of high system utilisation we consider how tasks of different criticality levels might be split, in some limited way, in order to increase the overall schedulability. We show that even minimal task splitting can drastically release slack previously unusable due to isolation requirements, which in turn provides a significant increase in schedulability.","PeriodicalId":245345,"journal":{"name":"Proceedings of the 24th International Conference on Real-Time Networks and Systems","volume":"31 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":"130172122","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: 8