Sufficient Temporal Independence and Improved Interrupt Latencies in a Real-Time Hypervisor

Beckert, Matthias; Neukirchner, Moritz; Ernst, Rolf; Petters, Stefan M.

doi:10.1145/2593069.2593222

Cited by 13 publications

(20 citation statements)

References 13 publications

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“…Becker et al present a promising technique [12] to allow interrupts in time partitioned systems to be handled at any time by monitoring interrupt interarrival and execution time and delaying the interrupt when configured budgets are exceeded. Their idea fits very well to AUTOSAR's optional timing protection facility [3], which, if employed, requires developers to specify exactly these properties (budget and inter-arrival time) for every interrupt in the system configuration.…”

Section: Discussionmentioning

confidence: 99%

AUTOBEST: a united AUTOSAR-OS and ARINC 653 kernel

Zuepke

Bommert

Lohmann

2015

21st IEEE Real-Time and Embedded Technology and Applications Symposium

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Abstract-This paper presents AUTOBEST, a united AUTOSAR-OS and ARINC 653 RTOS kernel that addresses the requirements of both automotive and avionics domains. We show that their domain-specific requirements have a common basis and can be implemented with a small partitioning microkernel-based design on embedded microcontrollers with memory protection (MPU) support. While both, AUTOSAR and ARINC 653, use a unified task model in the kernel, we address their differences in dedicated user space libraries. Based on the kernel abstractions of futexes and lazy priority switching, these libraries provide domain specific synchronization mechanisms. Our results show that thereby it is possible to get the best of both worlds: AUTOBEST combines avionics safety with the resource-efficiency known from automotive systems.

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Section: Discussionmentioning

confidence: 99%

AUTOBEST: a united AUTOSAR-OS and ARINC 653 kernel

Zuepke

Bommert

Lohmann

2015

21st IEEE Real-Time and Embedded Technology and Applications Symposium

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“…In [7] the authors considered the interrupt request (IRQ) handling in systems, where the execution of user-level IRQ handler is bounded to the TDMA scheduling scheme. As the TDMA based blocking time is dominating, high IRQ response times might be the result.…”

Section: Related Workmentioning

confidence: 99%

“…However, the described IRQ shaping from [7] only shows how to improve IRQ response times, but it does not consider how to design a partition setup that can use this method. Also, the known methods for time partition optimization are designed for systems with RMS inside partitions.…”

Section: Contributionmentioning

confidence: 99%

“…Also, the known methods for time partition optimization are designed for systems with RMS inside partitions. In this paper we propose an algorithm to generate an optimal TDMA cycle for sufficient temporal independence as presented in [7]. The algorithm is designed to calculate a possible set of time partitions with a maximum amount of slack within the TDMA cycle, based on task activation patterns.…”

Section: Contributionmentioning

confidence: 99%

“…This section will give a short introduction into monitoring based IRQ shaping, that was presented in [7]. The referenced paper also includes a much more detailed description of the architecture and a formal worst-case response time analysis for IRQ handling in such hypervisor systems.…”

Section: Monitoring Based Irq Shapingmentioning

confidence: 99%

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Designing time partitions for real-time hypervisor with sufficient temporal independence

Beckert

Ernst

2015

Proceedings of the 52nd Annual Design Automation Conference

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Virtualization techniques for embedded real-time systems, as known from the Integrated Modular Avionics (IMA) architecture of the ARINC653 standard, typically employ a TDMA scheduling to achieve temporal isolation among different virtualized partitions. Due to the fixed TDMA schedule, the worst case interrupt response times are significantly increased. An already proposed technique to mitigate this problem is to allow interrupts within an TDMA schedule, in order to achieve better interrupt response times while maintaining a sufficient degree of temporal independence via monitoring. In this paper we propose a novel approach that optimizes the TDMA schedule based on the partitions internal timing behavior and tasks parameters. The developed optimization algorithm generates a maximum amount of slack within the TDMA cycle. This slack is later used to interpose interrupts, while maintaining the interference with a monitor. We show correctness of the approach and evaluate it in a hypervisor implementation.

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Clock Synchronization in Virtualized Distributed Real-Time Systems Using IEEE 802.1AS and ACRN

Ruh¹,

Steiner

Fohler

2021

IEEE Access

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The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 764785, FORA -Fog Computing for Robotics and Industrial Automation ABSTRACT Virtualization of distributed real-time systems enables the consolidation of mixed-criticality functions on a shared hardware platform, easing system integration. Time-triggered communication and computation can act as an enabler of safe hard real-time systems. A time-triggered hypervisor that activates virtual CPUs according to a global schedule can provide the means to allow for a resource-efficient implementation of the time-triggered paradigm in virtualized distributed real-time systems. A prerequisite of time-triggered virtualization for hard real-time systems is providing access to a global time base to VMs and the hypervisor. A global time base results from clock synchronization with an upper bound on the clock synchronization precision. We present a formalization of the notion of time in virtualized distributed real-time systems. We use this formalization to propose a virtual clock condition that enables us to test the suitability of a virtual clock for the design of virtualized time-triggered real-time systems focusing on clock synchronization. We discuss and model how virtualization, particularly resource consolidation versus resource partitioning, degrades clock synchronization precision. Finally, we apply our insights to model the IEEE 802.1AS clock synchronization protocol and derive an upper bound on the clock synchronization precision of IEEE 802.1AS in a virtualized distributed real-time system. We present our implementation of a dependent clock for ACRN that can be synchronized to a grandmaster clock. The results of our experiments illustrate that a type-1 hypervisor like ACRN implementing the dependent clock paradigm yields native clock synchronization precision. Furthermore, we show that the upper bound of clock synchronization precision derived from our model holds for a series of experiments featuring native and virtualized setups.

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Sufficient Temporal Independence and Improved Interrupt Latencies in a Real-Time Hypervisor

Cited by 13 publications

References 13 publications

AUTOBEST: a united AUTOSAR-OS and ARINC 653 kernel

AUTOBEST: a united AUTOSAR-OS and ARINC 653 kernel

Designing time partitions for real-time hypervisor with sufficient temporal independence

Clock Synchronization in Virtualized Distributed Real-Time Systems Using IEEE 802.1AS and ACRN

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