Feasibility intervals for homogeneous multicores, asynchronous periodic tasks, and FJP schedulers

Nélis, Vincent; Yomsi, Patrick Meumeu; Goossens, Joël

doi:10.1145/2516821.2516848

Cited by 7 publications

(4 citation statements)

References 17 publications

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“…The same interval is used and tuned for fixed-job priority schedulers and independent tasks in [26].…”

Section: Multiprocessor Resultsmentioning

confidence: 99%

“…Uniform multiprocessor Unrelated multiprocessor FTP [23] FJP [15] FJP [16] Consv [2,8] Any [26] Any [4] gFTP [11] gFTP [10] gFTP [12] Any Comparison with other existing bounds In Table 1, the main results concerning periodicity are summarized. All the results assume a deterministic and memoryless scheduling algorithm.…”

Section: Uniprocessor Identical Multiprocessormentioning

confidence: 99%

See 1 more Smart Citation

Periodicity of real-time schedules for dependent periodic tasks on identical multiprocessor platforms

Goossens¹,

Grolleau²,

Cucu-Grosjean³

2016

Real-Time Syst

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This paper gives and proves correct a simulation interval for any schedule generated by a deterministic and memoryless scheduler (i.e., one where the scheduling decision is the same and unique for any two identical system states) for identical multiprocessor platforms. We first consider independent periodic tasks, then generalize the simulation interval to tasks sharing critical resources, and subject to precedence constraints or self-suspension. The simulation interval is based only on the periods, release times and deadlines, and is independent from any other parameters. It is proved large enough to cover any feasible schedule produced by any deterministic and memoryless scheduler on multiprocessor platforms, including non conservative schedulers. To the best of our knowledge, this simulation interval covers the largest class of tasks systems and scheduling algorithms on identical multiprocessor platforms ever studied. This simulation interval is used to derive a simulation algorithm using a linear space complexity. Finally, a generic exact schedulability test based on simulation is presented. This test can be applied only when sustainability is consistent with online variability of the tasks' parameters.

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“…The same interval is used and tuned for fixed-job priority schedulers and independent tasks in [26].…”

Section: Multiprocessor Resultsmentioning

confidence: 99%

Section: Uniprocessor Identical Multiprocessormentioning

confidence: 99%

Periodicity of real-time schedules for dependent periodic tasks on identical multiprocessor platforms

Goossens¹,

Grolleau²,

Cucu-Grosjean³

2016

Real-Time Syst

Self Cite

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“…A result is given in the case of offline schedulers for systems with precedence constraints in [4]. It is generalized to edf and to independent tasks in [30]: [0, 𝑂 max + 𝐻 𝑛 𝑖=1 (𝐶 𝑖 + 1)). Finally, a very general result for any deterministic and memoryless scheduler is given in [19] and is [0, 𝐻 𝑛 𝑖=1 ((𝑂 𝑖 +𝐷 𝑖 −𝑇 𝑖 ) 0 + 1)).…”

Section: Simulation Intervalsmentioning

confidence: 99%

Simulation intervals for uniprocessor real-time schedulers with preemption delay

Goossens

Masson

2022

Proceedings of the 30th International Conference on Real-Time Networks and Systems

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In the framework of embedded and time-critical systems we consider the scheduling of preemptive real-time periodic tasks upon uniprocessor. We consider the notion of simulation interval, a finite time interval such that the schedule starts to repeat in a cycle. The interest is to design a time interval which includes all possible (reachable) schedule states. Our study focuses on a model where preemption costs are explicitly considered, i.e., the time required by the real-time operating system (rtos) or the hardware to load the context of execution of preempted jobs. We present and prove correct a simulation interval for asynchronous arbitrary deadline tasks with preemption delays and that holds for any deterministic and memoryless scheduler upon uniprocessor. This first contribution is valid for all schedulers one can imagine (but deterministic and memoryless), including non-preemptive schedulers, not work-conserving, not necessarily popular "real-time" ones. We then consider a particular case, regarding the preemption delays, for edf scheduling for which we extend the work of Leung and Merril [25] showing that [0, 𝑂 max + 2 • 𝐻 ) is a simulation interval (significantly shorter than the general result). We also show that [0, 𝑆 𝑛 + 𝐻 ) from [17] remains a simulation interval for fixed task priority (ftp) schedulers. Before concluding we open a discussion on the scope of the results, paths for reducing pessimism as well as other potential results opened by this work. CCS CONCEPTS• Computer systems organization → Real-time operating systems.

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“…For more general task sets, we have less tight results. Baro et al (2012) provide an upper bound for the scheduling window for off-line scheduling: Grolleau et al (2013) give an upper bound until the schedule of deterministic "memoryless" schedulers becomes cyclic: Nélis et al (2013) give the following upper bound for the feasibility window of fixed job-level priority schedulers:…”

Section: Schedule Lengthmentioning

confidence: 99%

Off-line mapping of multi-rate dependent task sets to many-core platforms

2015

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This paper presents an approach to execute safety-critical applications on multi-and many-core processors in a predictable manner. We investigate three concrete platforms: the Intel Single-chip Cloud Computer, the Texas Instruments TMS320C6678 and the Tilera TILEmpower-Gx36. We define an execution model to safely execute dependent periodic task sets on these platforms. The four rules of the execution model entail that an off-line mapping of the application to the platform must be computed. The paper details our approach to automatically compute a valid mapping. Furthermore, we evaluate our approach, which is based on constraint programming, by applying it to several task sets that are derived from industrial applications.

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Feasibility intervals for homogeneous multicores, asynchronous periodic tasks, and FJP schedulers

Cited by 7 publications

References 17 publications

Periodicity of real-time schedules for dependent periodic tasks on identical multiprocessor platforms

Periodicity of real-time schedules for dependent periodic tasks on identical multiprocessor platforms

Simulation intervals for uniprocessor real-time schedulers with preemption delay

Off-line mapping of multi-rate dependent task sets to many-core platforms

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