DROPS

Issue

DARTS, Volume 7, Issue 1

Special Issue of the 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021)

Editors: Alessandro Biondi and Angeliki Kritikakou

Issue

DARTS, Volume 6, Issue 1

Special Issue of the 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)

Editors: Alessandro V. Papadopoulos and Alessandro Biondi

Document

Invited Paper

DOI: 10.4230/OASIcs.WCET.2024.5

Invited Paper: On the Granularity of Bandwidth Regulation in FPGA-Based Heterogeneous Systems on Chip

Authors: Gianluca Brilli, Giacomo Valente, Alessandro Capotondi, Tania Di Mascio, and Andrea Marongiu

Published in: OASIcs, Volume 121, 22nd International Workshop on Worst-Case Execution Time Analysis (WCET 2024)

Abstract

Main memory sharing in commercial, FPGA-based Heterogeneous System on Chips (HeSoCs) can cause significant interference, and ultimately severe slowdown of the executing workload, which bars the adoption of such systems in the context of time-critical applications. Bandwidth regulation approaches based on monitoring and throttling are widely adopted also in commercial hardware to improve the system quality of service (QoS), and previous work has shown that the finer the granularity of the mechanism, the more effective the QoS control. Different mechanisms, however, might exploit more or less effectively the available residual memory bandwidth, provided that the QoS requirement is satisfied. In this paper we present an exhaustive experimental evaluation of how three bandwidth regulation mechanisms with coarse, fine and ultra-fine granularity compare in terms of exploitation of the system memory bandwidth. Our results show that a very fine-grained regulation mechanism might experience worse system-level memory bandwidth exploitation compared to a coarser-grained approach.

Cite as

Gianluca Brilli, Giacomo Valente, Alessandro Capotondi, Tania Di Mascio, and Andrea Marongiu. Invited Paper: On the Granularity of Bandwidth Regulation in FPGA-Based Heterogeneous Systems on Chip. In 22nd International Workshop on Worst-Case Execution Time Analysis (WCET 2024). Open Access Series in Informatics (OASIcs), Volume 121, pp. 5:1-5:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{brilli_et_al:OASIcs.WCET.2024.5,
  author =	{Brilli, Gianluca and Valente, Giacomo and Capotondi, Alessandro and Di Mascio, Tania and Marongiu, Andrea},
  title =	{{Invited Paper: On the Granularity of Bandwidth Regulation in FPGA-Based Heterogeneous Systems on Chip}},
  booktitle =	{22nd International Workshop on Worst-Case Execution Time Analysis (WCET 2024)},
  pages =	{5:1--5:11},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-346-1},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{121},
  editor =	{Carle, Thomas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2024.5},
  URN =		{urn:nbn:de:0030-drops-204732},
  doi =		{10.4230/OASIcs.WCET.2024.5},
  annote =	{Keywords: Bandwidth Regulation, System-on-Chip, FPGA}
}

Document

DOI: 10.4230/LIPIcs.ECRTS.2024.3

Reachability-Based Response-Time Analysis of Preemptive Tasks Under Global Scheduling

Authors: Pourya Gohari, Jeroen Voeten, and Mitra Nasri

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)

Abstract

Global scheduling reduces the average response times as it can use the available computing cores more efficiently for scheduling ready tasks. However, this flexibility poses challenges in accurately quantifying interference scenarios, often resulting in either conservative response-time analyses or scalability issues. In this paper, we present a new response-time analysis for preemptive periodic tasks (or job sets) subject to release jitter under global job-level fixed-priority (JLFP) scheduling. Our analysis relies on the notion of schedule-abstraction graph (SAG), a reachability-based response-time analysis known for its potential accuracy and efficiency. Up to this point, SAG was limited to non-preemptive tasks due to the complexity of handling preemption when the number of preemptions and the moments they occur are not known beforehand. In this paper, we introduce the concept of time partitions and demonstrate how it facilitates the extension of SAG for preemptive tasks. Moreover, our paper provides the first response-time analysis for the global EDF(k) policy - a JLFP scheduling policy introduced in 2003 to address the Dhall’s effect. Our experiments show that our analysis is significantly more accurate compared to the state-of-the-art analyses. For example, we identify 12 times more schedulable task sets than existing tests for the global EDF policy (e.g., for systems with 6 to 16 tasks, 70% utilization, and 4 cores) with an average runtime of 30 minutes. We show that EDF(k) outperforms global RM and EDF by scheduling on average 24.9% more task sets (e.g., for systems with 2 to 10 cores and 70% utilization). Moreover, for the first time, we show that global JLFP scheduling policies (particularly, global EDF(k)) are able to schedule task sets that are not schedulable using well-known partitioning heuristics.

Cite as

Pourya Gohari, Jeroen Voeten, and Mitra Nasri. Reachability-Based Response-Time Analysis of Preemptive Tasks Under Global Scheduling. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 3:1-3:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{gohari_et_al:LIPIcs.ECRTS.2024.3,
  author =	{Gohari, Pourya and Voeten, Jeroen and Nasri, Mitra},
  title =	{{Reachability-Based Response-Time Analysis of Preemptive Tasks Under Global Scheduling}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{3:1--3:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.3},
  URN =		{urn:nbn:de:0030-drops-203064},
  doi =		{10.4230/LIPIcs.ECRTS.2024.3},
  annote =	{Keywords: Response-time analysis, global scheduling, preemptive, job-level fixed-priority scheduling policy, multicore, schedule-abstraction graph}
}

Document

DOI: 10.4230/LIPIcs.ECRTS.2024.4

Tighter Worst-Case Response Time Bounds for Jitter-Based Self-Suspension Analysis

Authors: Mario Günzel, Georg von der Brüggen, and Jian-Jia Chen

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)

Abstract

Tasks are called self-suspending if they can yield their ready state (specifically, releasing the processor while having highest priority) despite being incomplete, for instance, to offload computation to an external device or when waiting on access rights for shared resources or data. This self-suspending behavior requires special treatment when applying analytical results to compute worst-case response time bounds. One typical treatment is modeling self-suspension as release jitter in a so-called jitter-based analysis. The state of the art, when considering task-level fixed-priority scheduling, individually quantifies the jitter term of each higher-priority task by its worst-case response time minus its worst-case execution time. This work tightens the jitter term by taking the execution behavior of the other higher-priority tasks into account. Our improved jitter-based analysis analytically dominates the previous jitter-based analysis. Moreover, an evaluation for synthetically generated sporadic tasks demonstrates that this jitter term results in tighter worst-case response time bounds for self-suspending tasks. We observe an improvement for up to 55.89 % of the tasksets compared to the previous jitter-based analysis.

Cite as

Mario Günzel, Georg von der Brüggen, and Jian-Jia Chen. Tighter Worst-Case Response Time Bounds for Jitter-Based Self-Suspension Analysis. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 4:1-4:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{gunzel_et_al:LIPIcs.ECRTS.2024.4,
  author =	{G\"{u}nzel, Mario and von der Br\"{u}ggen, Georg and Chen, Jian-Jia},
  title =	{{Tighter Worst-Case Response Time Bounds for Jitter-Based Self-Suspension Analysis}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{4:1--4:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.4},
  URN =		{urn:nbn:de:0030-drops-203074},
  doi =		{10.4230/LIPIcs.ECRTS.2024.4},
  annote =	{Keywords: Worst-Case Response Time, WCRT, Jitter, Self-Suspension, Analysis}
}

Document

DOI: 10.4230/LIPIcs.ECRTS.2024.5

Shared Resource Contention in MCUs: A Reality Check and the Quest for Timeliness

Authors: Daniel Oliveira, Weifan Chen, Sandro Pinto, and Renato Mancuso

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)

Abstract

Microcontrollers (MCUs) are steadily embracing multi-core technology to meet growing performance demands. This trend marks a shift from their traditionally simple, deterministic designs to more complex and inherently less predictable architectures. While shared resource contention is well-studied in mid to high-end embedded systems, the emergence of multi-core architectures in MCUs introduces unique challenges and characteristics that existing research has not fully explored. In this paper, we conduct an in-depth investigation of both mainstream and next-generation MCU-based platforms, aiming to identify the sources of contention on systems typically lacking these problems. We empirically demonstrate substantial contention effects across different MCU architectures (i.e., from single- to multi-core configurations), highlighting significant application slowdowns. Notably, we observe that slowdowns can reach several orders of magnitude, with the most extreme cases showing up to a 3800x (times, not percent) increase in execution time. To address these issues, we propose and evaluate muTPArtc, a novel mechanism designed for Timely Progress Assessment (TPA) and TPA-based runtime control specifically tailored to MCUs. muTPArtc is an MCU-specialized TPA-based mechanism that leverages hardware facilities widely available in commercial off-the-shelf MCUs (i.e., hardware breakpoints and cycle counters) to successfully monitor applications' progress, detect, and mitigate timing violations. Our results demonstrate that muTPArtc effectively manages performance degradation due to interference, requiring only minimal modifications to the build pipeline and no changes to the source code of the target application, while incurring minor overheads.

Cite as

Daniel Oliveira, Weifan Chen, Sandro Pinto, and Renato Mancuso. Shared Resource Contention in MCUs: A Reality Check and the Quest for Timeliness. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 5:1-5:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{oliveira_et_al:LIPIcs.ECRTS.2024.5,
  author =	{Oliveira, Daniel and Chen, Weifan and Pinto, Sandro and Mancuso, Renato},
  title =	{{Shared Resource Contention in MCUs: A Reality Check and the Quest for Timeliness}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{5:1--5:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.5},
  URN =		{urn:nbn:de:0030-drops-203088},
  doi =		{10.4230/LIPIcs.ECRTS.2024.5},
  annote =	{Keywords: multi-core microcontrollers, shared resources contention, progress-aware regulation}
}

Document

DOI: 10.4230/LIPIcs.ECRTS.2024.6

Optimizing Per-Core Priorities to Minimize End-To-End Latencies

Authors: Francesco Paladino, Alessandro Biondi, Enrico Bini, and Paolo Pazzaglia

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)

Abstract

Logical Execution Time (LET) allows decoupling the schedule of real-time periodic tasks from their communication, with the advantage of isolating the communication pattern from the variability of the schedule. However, when such tasks are organized in chains, the usage of LET at the task level does not necessarily transfer the same LET properties to the chain level. In this paper, we extend a LET-like model from tasks to chains spanning over multiple cores. We leverage the designed constant latency chains to optimize per-core priority assignment. Finally, we also provide a set of heuristic algorithms, that are compared in a large-scale experimental evaluation.

Cite as

Francesco Paladino, Alessandro Biondi, Enrico Bini, and Paolo Pazzaglia. Optimizing Per-Core Priorities to Minimize End-To-End Latencies. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 6:1-6:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{paladino_et_al:LIPIcs.ECRTS.2024.6,
  author =	{Paladino, Francesco and Biondi, Alessandro and Bini, Enrico and Pazzaglia, Paolo},
  title =	{{Optimizing Per-Core Priorities to Minimize End-To-End Latencies}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{6:1--6:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.6},
  URN =		{urn:nbn:de:0030-drops-203094},
  doi =		{10.4230/LIPIcs.ECRTS.2024.6},
  annote =	{Keywords: Cause-Effect Chains, Logical Execution Time, End-to-End Latency, Design Optimization, Task Priorities, Data Age, Reaction Time}
}

Document

DOI: 10.4230/LIPIcs.ECRTS.2024.7

The Omnivisor: A Real-Time Static Partitioning Hypervisor Extension for Heterogeneous Core Virtualization over MPSoCs

Authors: Daniele Ottaviano, Francesco Ciraolo, Renato Mancuso, and Marcello Cinque

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)

Abstract

Following the needs of industrial applications, virtualization has emerged as one of the most effective approaches for the consolidation of mixed-criticality systems while meeting tight constraints in terms of space, weight, power, and cost (SWaP-C). In embedded platforms with homogeneous processors, a wealth of works have proposed designs and techniques to enforce spatio-temporal isolation by leveraging well-understood virtualization support. Unfortunately, achieving the same goal on heterogeneous MultiProcessor Systems-on-Chip (MPSoCs) has been largely overlooked. Modern hypervisors are designed to operate exclusively on main cores, with little or no consideration given to other co-processors within the system, such as small microcontroller-level CPUs or soft-cores deployed on programmable logic (FPGA). Typically, hypervisors consider co-processors as I/O devices allocated to virtual machines that run on primary cores, yielding full control and responsibility over them. Nevertheless, inadequate management of these resources can lead to spatio-temporal isolation issues within the system. In this paper, we propose the Omnivisor model as a paradigm for the holistic management of heterogeneous platforms. The model generalizes the features of real-time static partitioning hypervisors to enable the execution of virtual machines on processors with different Instruction Set Architectures (ISAs) within the same MPSoC. Moreover, the Omnivisor ensures temporal and spatial isolation between virtual machines by integrating and leveraging a variety of hardware and software protection mechanisms. The presented approach not only expands the scope of virtualization in MPSoCs but also enhances the overall system reliability and real-time performance for mixed-criticality applications. A full open-source reference implementation of the Omnivisor based on the Jailhouse hypervisor is provided, targeting ARM real-time processing units and RISC-V soft-cores on FPGA. Experimental results on real hardware show the benefits of the solution, including enabling the seamless launch of virtual machines on different ISAs and extending spatial/temporal isolation to heterogenous cores with enhanced regulation policies.

Cite as

Daniele Ottaviano, Francesco Ciraolo, Renato Mancuso, and Marcello Cinque. The Omnivisor: A Real-Time Static Partitioning Hypervisor Extension for Heterogeneous Core Virtualization over MPSoCs. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 7:1-7:27, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{ottaviano_et_al:LIPIcs.ECRTS.2024.7,
  author =	{Ottaviano, Daniele and Ciraolo, Francesco and Mancuso, Renato and Cinque, Marcello},
  title =	{{The Omnivisor: A Real-Time Static Partitioning Hypervisor Extension for Heterogeneous Core Virtualization over MPSoCs}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{7:1--7:27},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.7},
  URN =		{urn:nbn:de:0030-drops-203107},
  doi =		{10.4230/LIPIcs.ECRTS.2024.7},
  annote =	{Keywords: Mixed-Criticality, Embedded Virtualization, Real-Time Systems, MPSoCs}
}

Document

DOI: 10.4230/LIPIcs.ECRTS.2024.15

Predictable GPU Sharing in Component-Based Real-Time Systems

Authors: Syed W. Ali, Zelin Tong, Joseph Goh, and James H. Anderson

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)

Abstract

This paper presents a real-time locking protocol whose design was motivated by the goal of enabling safe GPU sharing in time-sliced component-based systems. This locking protocol enables a GPU to be shared concurrently across, and utilized within, isolated components with predictable execution times. It relies on a novel resizing technique where GPU work is dimensioned on-the-fly to run on partitions of an NVIDIA GPU. This technique can be applied to any component that internally utilizes global CPU scheduling. The proposed locking protocol enables increased GPU parallelism and reduces GPU capacity loss with analytically provable benefits.

Cite as

Syed W. Ali, Zelin Tong, Joseph Goh, and James H. Anderson. Predictable GPU Sharing in Component-Based Real-Time Systems. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 15:1-15:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{ali_et_al:LIPIcs.ECRTS.2024.15,
  author =	{Ali, Syed W. and Tong, Zelin and Goh, Joseph and Anderson, James H.},
  title =	{{Predictable GPU Sharing in Component-Based Real-Time Systems}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{15:1--15:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.15},
  URN =		{urn:nbn:de:0030-drops-203183},
  doi =		{10.4230/LIPIcs.ECRTS.2024.15},
  annote =	{Keywords: GPU locking protocols, real-time locking protocols, priority-inversion blocking, component-based systems}
}

Document

DOI: 10.4230/LIPIcs.ECRTS.2023.9

Bounding the Data-Delivery Latency of DDS Messages in Real-Time Applications

Authors: Gerlando Sciangula, Daniel Casini, Alessandro Biondi, Claudio Scordino, and Marco Di Natale

Published in: LIPIcs, Volume 262, 35th Euromicro Conference on Real-Time Systems (ECRTS 2023)

Abstract

Many modern applications need to run on massively interconnected sets of heterogeneous nodes, ranging from IoT devices to edge nodes up to the Cloud. In this scenario, communication is often implemented using the publish-subscribe paradigm. The Data Distribution Service (DDS) is a popular middleware specification adopting such a paradigm. The DDS is becoming a key enabler for massively distributed real-time applications, with popular frameworks such as ROS 2 and AUTOSAR Adaptive building on it. However, no formal modeling and analysis of the timing properties of DDS has been provided to date. This paper fills this gap by providing an abstract model for DDS systems that can be generalized to any implementation compliant with the specification. A concrete instance of the generic DDS model is provided for the case of eProsima’s FastDDS, which is eventually used to provide a real-time analysis that bounds the data-delivery latency of DDS messages. Finally, this paper reports on an evaluation based on a representative automotive application from the WATERS 2019 challenge by Bosch.

Cite as

Gerlando Sciangula, Daniel Casini, Alessandro Biondi, Claudio Scordino, and Marco Di Natale. Bounding the Data-Delivery Latency of DDS Messages in Real-Time Applications. In 35th Euromicro Conference on Real-Time Systems (ECRTS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 262, pp. 9:1-9:26, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{sciangula_et_al:LIPIcs.ECRTS.2023.9,
  author =	{Sciangula, Gerlando and Casini, Daniel and Biondi, Alessandro and Scordino, Claudio and Di Natale, Marco},
  title =	{{Bounding the Data-Delivery Latency of DDS Messages in Real-Time Applications}},
  booktitle =	{35th Euromicro Conference on Real-Time Systems (ECRTS 2023)},
  pages =	{9:1--9:26},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-280-8},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{262},
  editor =	{Papadopoulos, Alessandro V.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2023.9},
  URN =		{urn:nbn:de:0030-drops-180381},
  doi =		{10.4230/LIPIcs.ECRTS.2023.9},
  annote =	{Keywords: DDS, real-time systems, response-time analysis, end-to-end latency, CPA}
}

Document

DOI: 10.4230/LIPIcs.ECRTS.2023.18

Replication-Based Scheduling of Parallel Real-Time Tasks

Authors: Federico Aromolo, Geoffrey Nelissen, and Alessandro Biondi

Published in: LIPIcs, Volume 262, 35th Euromicro Conference on Real-Time Systems (ECRTS 2023)

Abstract

Multiprocessors have become the standard computing platform for real-time embedded systems. To efficiently leverage the computational power of such platforms, software tasks are often characterized by an internal structure where concurrent subtasks can execute in parallel on different processors. Existing strategies for the scheduling of parallel real-time tasks on multiprocessor platforms, such as partitioned, global, and federated scheduling, were inspired by earlier techniques that were not conceived to explicitly support parallel tasks, thus carrying advantages but also well-known limitations. This paper introduces replication-based scheduling, a specialized scheduling paradigm for parallel real-time DAG tasks. Replication-based scheduling leverages the internal structure of the parallel tasks to assign replicas of the subtasks to different processors, while ensuring that exactly one replica of each subtask will be executed at runtime for every task instance. This approach aims at preserving the advantages of partitioned scheduling while simplifying the timing analysis. The replication-based scheduling framework is first defined, together with a strategy for implementing replication-based scheduling in real-time operating systems. Then, offline allocation strategies for subtask replicas and a response-time analysis are presented. In the provided experiments, the schedulability achieved with replication-based scheduling is compared with that of existing techniques for the scheduling of parallel real-time tasks on multiprocessors.

Cite as

Federico Aromolo, Geoffrey Nelissen, and Alessandro Biondi. Replication-Based Scheduling of Parallel Real-Time Tasks. In 35th Euromicro Conference on Real-Time Systems (ECRTS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 262, pp. 18:1-18:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{aromolo_et_al:LIPIcs.ECRTS.2023.18,
  author =	{Aromolo, Federico and Nelissen, Geoffrey and Biondi, Alessandro},
  title =	{{Replication-Based Scheduling of Parallel Real-Time Tasks}},
  booktitle =	{35th Euromicro Conference on Real-Time Systems (ECRTS 2023)},
  pages =	{18:1--18:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-280-8},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{262},
  editor =	{Papadopoulos, Alessandro V.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2023.18},
  URN =		{urn:nbn:de:0030-drops-180477},
  doi =		{10.4230/LIPIcs.ECRTS.2023.18},
  annote =	{Keywords: Real-Time Systems, Scheduling Algorithms, Schedulability Analysis, Parallel Tasks}
}

Document

Artifact

DOI: 10.4230/DARTS.8.1.5

Response-Time Analysis for Self-Suspending Tasks Under EDF Scheduling (Artifact)

Authors: Federico Aromolo, Alessandro Biondi, and Geoffrey Nelissen

Published in: DARTS, Volume 8, Issue 1, Special Issue of the 34th Euromicro Conference on Real-Time Systems (ECRTS 2022)

Abstract

This artifact provides the means to validate and reproduce the experimental results presented in the related paper "Response-Time Analysis for Self-Suspending Tasks Under EDF Scheduling". The paper introduces a response-time analysis for constrained-deadline self-suspending tasks scheduled under EDF on a uniprocessor system, based on a model transformation from self-suspending sporadic tasks to sporadic tasks with jitter. In the experimental evaluation presented in the paper, the performance of the proposed analysis approach for self-suspending tasks is compared with that of existing suspension-oblivious and suspension-aware analysis techniques.

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Federico Aromolo, Alessandro Biondi, and Geoffrey Nelissen. Response-Time Analysis for Self-Suspending Tasks Under EDF Scheduling (Artifact). In Special Issue of the 34th Euromicro Conference on Real-Time Systems (ECRTS 2022). Dagstuhl Artifacts Series (DARTS), Volume 8, Issue 1, pp. 5:1-5:2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@Article{aromolo_et_al:DARTS.8.1.5,
  author =	{Aromolo, Federico and Biondi, Alessandro and Nelissen, Geoffrey},
  title =	{{Response-Time Analysis for Self-Suspending Tasks Under EDF Scheduling (Artifact)}},
  pages =	{5:1--5:2},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2022},
  volume =	{8},
  number =	{1},
  editor =	{Aromolo, Federico and Biondi, Alessandro and Nelissen, Geoffrey},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.8.1.5},
  URN =		{urn:nbn:de:0030-drops-165012},
  doi =		{10.4230/DARTS.8.1.5},
  annote =	{Keywords: Real-Time Systems, Schedulability Analysis, Self-Suspending Tasks, EDF Scheduling}
}

Document

DOI: 10.4230/LIPIcs.ECRTS.2022.13

Response-Time Analysis for Self-Suspending Tasks Under EDF Scheduling

Authors: Federico Aromolo, Alessandro Biondi, and Geoffrey Nelissen

Published in: LIPIcs, Volume 231, 34th Euromicro Conference on Real-Time Systems (ECRTS 2022)

Abstract

The self-suspending task model proved to be particularly effective in capturing the timing behavior of real-time systems characterized by complex execution patterns, such as computation offloading to hardware accelerators, inter-core synchronization by means of multiprocessor locking protocols, and highly parallel computation. Most of the existing results for the timing analysis of self-suspending tasks do not support the widely adopted Earliest Deadline First (EDF) scheduling algorithm, being instead primarily focused on fixed-priority scheduling. This paper presents a response-time analysis for constrained-deadline self-suspending tasks scheduled under EDF on a uniprocessor system. The proposed analysis is based on a model transformation from self-suspending sporadic tasks to sporadic tasks with jitter, which can then be analyzed using a state-of-the-art analysis method for EDF scheduling. Experimental results are presented to compare the performance of the proposed technique in terms of schedulability ratio with that of the pessimistic suspension-oblivious approach and with a less general technique for task sets with implicit deadlines.

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Federico Aromolo, Alessandro Biondi, and Geoffrey Nelissen. Response-Time Analysis for Self-Suspending Tasks Under EDF Scheduling. In 34th Euromicro Conference on Real-Time Systems (ECRTS 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 231, pp. 13:1-13:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@InProceedings{aromolo_et_al:LIPIcs.ECRTS.2022.13,
  author =	{Aromolo, Federico and Biondi, Alessandro and Nelissen, Geoffrey},
  title =	{{Response-Time Analysis for Self-Suspending Tasks Under EDF Scheduling}},
  booktitle =	{34th Euromicro Conference on Real-Time Systems (ECRTS 2022)},
  pages =	{13:1--13:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-239-6},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{231},
  editor =	{Maggio, Martina},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2022.13},
  URN =		{urn:nbn:de:0030-drops-163306},
  doi =		{10.4230/LIPIcs.ECRTS.2022.13},
  annote =	{Keywords: Real-Time Systems, Schedulability Analysis, Self-Suspending Tasks, EDF Scheduling}
}

Document

DOI: 10.4230/LIPIcs.ECRTS.2021.13

Scheduling Replica Voting in Fixed-Priority Real-Time Systems

Authors: Pietro Fara, Gabriele Serra, Alessandro Biondi, and Ciro Donnarumma

Published in: LIPIcs, Volume 196, 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021)

Abstract

Reliability and safety are mandatory requirements for safety-critical embedded systems. The design of a fault-tolerant system is required in many fields (e.g., railway, automotive, avionics) and redundancy helps in achieving this goal. Redundant systems typically leverage voting techniques applied to the outputs produced by tasks to detect and even tolerate failures. This paper studies the integration of distributed voting protocols in fixed-priority real-time systems from a scheduling perspective. It analyzes two scheduling strategies for implementing voting. One is attractive and friendly for software developers and based on suspending the task execution until the replica provides the data to be voted. The other one is inspired by the Logical Execution Time (LET) paradigm and requires introducing additional tasks in the system to accomplish voting-related activities. Queuing and delays introduced by inter-replica communication interfaces are also analyzed. Experimental results are finally presented to compare the two strategies, showing that LET-inspired voting is much more predictable and hence more suitable than the other strategy for fixed-priority real-time systems.

Cite as

Pietro Fara, Gabriele Serra, Alessandro Biondi, and Ciro Donnarumma. Scheduling Replica Voting in Fixed-Priority Real-Time Systems. In 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 196, pp. 13:1-13:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{fara_et_al:LIPIcs.ECRTS.2021.13,
  author =	{Fara, Pietro and Serra, Gabriele and Biondi, Alessandro and Donnarumma, Ciro},
  title =	{{Scheduling Replica Voting in Fixed-Priority Real-Time Systems}},
  booktitle =	{33rd Euromicro Conference on Real-Time Systems (ECRTS 2021)},
  pages =	{13:1--13:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-192-4},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{196},
  editor =	{Brandenburg, Bj\"{o}rn B.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2021.13},
  URN =		{urn:nbn:de:0030-drops-139449},
  doi =		{10.4230/LIPIcs.ECRTS.2021.13},
  annote =	{Keywords: Real-time systems, safety-critical systems, voting, redundancy, fault-tolerance, logical execution time}
}

Document

Front Matter

DOI: 10.4230/DARTS.7.1.0

Front Matter - ECRTS 2021 Artifacts, Table of Contents, Artifact Evaluation Committee

Authors: Alessandro Biondi and Angeliki Kritikakou

Published in: DARTS, Volume 7, Issue 1, Special Issue of the 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021)

Abstract

Front Matter, Table of Contents, Preface, Conference Organization

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Special Issue of the 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021). Dagstuhl Artifacts Series (DARTS), Volume 7, Issue 1, pp. 0:i-0:x, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@Article{biondi_et_al:DARTS.7.1.0,
  author =	{Biondi, Alessandro and Kritikakou, Angeliki},
  title =	{{Front Matter - ECRTS 2021 Artifacts, Table of Contents, Artifact Evaluation Committee}},
  pages =	{0:i--0:x},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2021},
  volume =	{7},
  number =	{1},
  editor =	{Biondi, Alessandro and Kritikakou, Angeliki},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.7.1.0},
  URN =		{urn:nbn:de:0030-drops-139794},
  doi =		{10.4230/DARTS.7.1.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}

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