Applying Sensitivity Analysis in Real-Time Distributed Systems

Racu, Razvan; Jersak, Marek; Ernst, Rolf

doi:10.1109/rtas.2005.10

Cited by 46 publications

(38 citation statements)

References 14 publications

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“…As an extension of LL test, an utilization bound test for tasks with pre-period deadlines has been used Racu et al (2005), and some changes were made to find an approximate value for˛. We termed this the LLM test.…”

Section: Llm Approachmentioning

confidence: 99%

High performance dynamic voltage/frequency scaling algorithm for real-time dynamic load management

Coronel

Simó

2012

Journal of Systems and Software

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Modern cyber-physical systems assume a complex and dynamic interaction between the real world and the computing system in real-time. In this context, changes in the physical environment trigger changes in the computational load to execute. On the other hand, task migration services offered by networked control systems require also management of dynamic real-time computing load in nodes. In such systems it would be difficult, if not impossible, to analyse off-line all the possible combinations of processor loads. For this reason, it is worthwhile attempting to define new flexible architectures that enable computing systems to adapt to potential changes in the environment.We assume a system composed by three main components: the first one is responsible of the manage-ment of the requests arisen when new tasks require to be executed. This management component asks to the second component about the resources available to accept the new tasks. The second component performs a feasibility analysis to determine if the new tasks can be accepted coping with its real-time constraints. A new processor speed is also computed. A third component monitors the execution of tasks applying a fixed priority scheduling policy and additionally controlling the frequency of the processor. This paper focus on the second component providing a "correct" (a task never is accepted if it is not schedulable) and "near-exact" (a task is rarely rejected if it is schedulable) algorithm that can be appli-cable in practice because its low/medium and predictable computational cost. The algorithm analyses task admission in terms of processor frequency scaling. The paper presents the details of a novel algo-rithm to analyse tasks admission and processor frequency assignment. Additionally, we perform several simulations to evaluate the comparative performance of the proposed approach. This evaluation is made in terms of energy consumption, task rejection ratios, and real computing costs. The results of simula-tions show that from the cost, execution predictability, and task acceptance points of view, the proposed algorithm mostly outperforms other constant voltage scaling algorithms.

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Section: Llm Approachmentioning

confidence: 99%

High performance dynamic voltage/frequency scaling algorithm for real-time dynamic load management

Coronel

Simó

2012

Journal of Systems and Software

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“…Sensitivity analysis determines the boundaries between working and non-working systems for arbitrary properties. The one-dimensional sensitivity analyses approaches presented in [13,15], for instance, can capture the effects of single system property variations taking into account complex global timing effects. They are capable of calculating the maximum (or minimum) permissible values for large variety of system properties, including worst-case execution times, communication volumes, input data rates, processor, communication link performance, etc.…”

Section: Related Workmentioning

confidence: 99%

“…Sensitivity analyses [13,15] can capture the global effects of system property variations. They are capable of calculating the boundaries representing the transition between working and non-working systems with respect to a large variety of system properties, including worst-case execution times, communication volumes, input data rates, processor and communication link performance, etc.…”

Section: Sensitivity Analysismentioning

confidence: 99%

Methods for multi-dimensional robustness optimization in complex embedded systems

Hamann¹,

Racu²,

Ernst³

2007

Proceedings of the 7th ACM &Amp; IEEE International Conference on Embedded Software - EMSOFT '07

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Design space exploration of embedded systems typically focuses on classical design goals such as cost, timing, buffer sizes, and power consumption. Robustness criteria, i.e. sensitivity of the system to variations of properties like execution and transmission delays, input data rates, CPU clock rates, etc., has found less attention despite its practical relevance.In this paper we introduce multi-dimensional robustness metrics, expressing the static and dynamic design robustness of a given system, the former assuming a fixed parameter configuration, and the latter including parameter adaptations as response to property variations. Additionally, we propose a metric measuring the robustness gain that can be achieved through system reconfigurability.Since determining multi-dimensional robustness is computationally expensive we introduce efficient exploration methods based on a stochastic sensitivity analysis technique capable of deriving upper and lower robustness bounds for a given system with low computational effort. We demonstrate the robustness optimization methods by means of a small but realistic case study.

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“…In other words, they do not deal properly with the design of parametric systems. On the other hand, complementing the application of formal methods with a binary search on the parameter space [22] can be hardly a scalable solution when the number of parameters is considerable and it assumes a "monotonic" relation between parameters and feasibility, which is not necessarily true in the general case.…”

Section: Introductionmentioning

confidence: 99%