A utilization bound for aperiodic tasks and priority driven scheduling

Abdelzaher, Tarek; Sharma, Vivek; Lu, Chenyang

doi:10.1109/tc.2004.1261839

Cited by 95 publications

(84 citation statements)

References 35 publications

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“…Then, W t is a discrete-time random variable representing the amount of workload entering a system during the t th sampling interval (that is, the workload trace) 1 . The mean intensity (or utilization) of the workload W t is defined as E[W t ]/T .…”

Section: Formal "On-off" Modelmentioning

confidence: 99%

“…The analysis described in this section is based on a recent schedulability test by [1] that basically requires the synthetic utilization, denoted as U (t), to be under a certain utilization bound B. Using this expression, we derive a new schedulability test, that is based on the pending computation at time t (C(t)).…”

Section: Schedulability Analysismentioning

confidence: 99%

“…The seminal work [24] established a bound for aperiodic tasks when deadline equals to their period. In a recent work [1], a bound for aperiodic tasks was derived using a utilization-like metric called synthetic utilization. The synthetic utilization is defined as the utilization contributed by the set of current task invocations at time t, given by the expression:…”

Section: Schedulability Analysismentioning

confidence: 99%

“…Such a set of tasks behaves statistically as a fractional Brownian motion (fBm). The analytical analysis of schedulability is based on applying the concept of synthetic utilization [1] to the previous "on-off" model. Results show the dependency of schedulability on the Hurst parameter.…”

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confidence: 99%

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On the nature and impact of self-similarity in real-time systems

Hernández-Orallo

Vila-Carbó

2012

Real-Time Syst

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On the nature and impact of self-similarity in real-time systems Enrique Hernández-Orallo and Joan Vila-Carbó the date of receipt and acceptance should be inserted later Abstract In real-time systems with highly variable task execution times simplistic task models are insufficient to accurately model and to analyze the system. Variability can be tackled using distributions rather than a single value, but the proper characterization depends on the degree of variability. Self-similarity is one of the deepest kinds of variability. It characterizes the fact that a workload is not only highly variable, but it is also bursty on many time-scales. This paper identifies in which situations this source of indeterminism can appear in a real-time system: the combination of variability in task inter-arrival times and execution times. Although self-similarity is not a claim for all systems with variable execution times, it is not unusual in some applications with real-time requirements, like video processing, networking and gaming.The paper shows how to properly model and to analyze self-similar task sets and how improper modeling can mask deadline misses. The paper derives an analytical expression for the dependence of the deadline miss ratio on the degree of self-similarity and proofs its negative impact on real-time systems performance through system's modeling and simulation. This study about the nature and impact of self-similarity on soft real-time systems can help to reduce its effects, to choose the proper scheduling policies, and to avoid its causes at system design time.

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Section: Formal "On-off" Modelmentioning

confidence: 99%

Section: Schedulability Analysismentioning

confidence: 99%

Section: Schedulability Analysismentioning

confidence: 99%

mentioning

confidence: 99%

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On the nature and impact of self-similarity in real-time systems

Hernández-Orallo

Vila-Carbó

2012

Real-Time Syst

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“…Utilization bounds of RMS/DMS in multiprocessor systems have also been derived in [12], [13], [14], [15], [16], [17]. Some important utilization bounds for nonperiodic systems are derived in [18], [19], [20], [21]. A more detailed summary of the literature will be provided in the next section.…”

Section: Introductionmentioning

confidence: 99%

A General Framework for Parameterized Schedulability Bound Analysis of Real-Time Systems

Liu

Zhao

2010

IEEE Trans. Comput.

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Abstract-In real-time systems, utilization-based schedulability test is a common approach to determine whether or not tasks can be admitted without violating deadline requirements. The test is extremely simple, since it only needs to compare the utilization of the tasks with a predetermined bound. As such, utilization-based schedulability tests are suitable for online use. The challenge is how to derive a reasonable utilization bound for a given system. Most existing results are obtained on a case-by-case basis because of their analytical complexity. In this paper, we develop a flexible and unified representation framework of real-time systems (i.e., tasks and schedulers) based on network calculus techniques. Our representation framework, together with the proposed bound derivation method, leads to a general bound result, which is applicable to a large family of real-time systems.

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