scholarly journals An optimal energy aware aperiodic task server for autonomous IoT sensors

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Rola El Osta ◽  
Maryline Chetto ◽  
Hussein El Ghor
Keyword(s):  
Real Time ◽  
Response Times ◽  
Periodic Tasks ◽  
Energy Aware ◽  
Storage Unit ◽  
Arrival Times ◽  
Energy Storage Unit ◽  
Aperiodic Tasks ◽  
Energy Harvesting System ◽  
Aperiodic Task

A real-time applicative software consists of both aperiodic and periodic tasks. The periodic tasks have regular arrival times and strict deadlines. The aperiodic tasks have irregular arrival times and no deadline. The objective of an optimal aperiodic task server is to guarantee minimal response times for the aperiodic tasks and no violation of hard deadlines for periodic tasks. We consider a real-time energy harvesting system composed of energy harvester, energy storage unit, uniprocessing unit and the real-time tasks. We introduce a novel periodic task scheduler, namely SSP which is an extension of the slack stealing server so as to cope with fluctuations in energy availability. Experimental results show that the proposed algorithm achieves better performance in terms of aperiodic responsiveness. Simulations have been conducted for various settings of workloads and harvested energy profiles.

Scheduling of Aperiodic Tasks on Multicore Systems

2020 ◽  
pp. 14-35
Author(s):  
Shruti Jadon ◽  
Rama Shankar Yadav
Keyword(s):  
Response Time ◽  
Real Time ◽  
Multicore Systems ◽  
Multicore Processor ◽  
Periodic Tasks ◽  
Aperiodic Tasks ◽  
Multicore System ◽  
Hard Real Time ◽  
Work Done ◽  
Aperiodic Task

For a hard real-time multicore system, the two important issues that are required to be addressed are feasibility of a task set and balancing of load amongst the cores of the multicore systems. Most of the previous work done considers the scheduling of periodic tasks on a multicore system. This chapter deals with scheduling of aperiodic tasks on a multicore system in a hard real-time environment. In this regard, a multicore total bandwidth server (MTBS) is proposed which schedules the aperiodic tasks with already guaranteed periodic tasks amongst the cores of the multicore processor. The proposed MTBS algorithm works by computing a virtual deadline for every aperiodic task that is arriving to the system. Apart from schedulability of aperiodic tasks, the MTBS approach also focuses on reducing the response time of aperiodic tasks. The simulation studies of MTBS were carried out to find the effectiveness of the proposed approach, and it is also compared with the existing strategies.

Optimal Slack Stealing Servicing for Real-Time Energy Harvesting Systems

2020 ◽  
Vol 63 (10) ◽  
pp. 1537-1546
Author(s):  
Rola El Osta ◽  
Maryline Chetto ◽  
Hussein El Ghor
Keyword(s):  
Real Time ◽  
Response Times ◽  
Periodic Tasks ◽  
Real Time Scheduling ◽  
Energy Harvesters ◽  
Aperiodic Tasks ◽  
Harvesting Systems ◽  
Time Scheduling ◽  
Hard Deadline ◽  
Time And Energy

Abstract We consider the problem of real-time scheduling in uniprocessor devices powered by energy harvesters. In particular, we focus on mixed sets of tasks with time and energy constraints: hard deadline periodic tasks and soft aperiodic tasks without deadlines. We present an optimal aperiodic servicing algorithm that minimizes the response times of aperiodic tasks without compromising the schedulability of hard deadline periodic tasks. The server, called Slack Stealing with energy Preserving (SSP), is designed based on a slack stealing mechanism that profits whenever possible from available spare processing time and energy. We analytically establish the optimality of SSP. Our simulation results validate our theoretical analysis.

scholarly journals Ensuring the sustainability of real-time embedded system under both QoS and Energy Constraints

2019 ◽  
Vol 281 ◽  
pp. 04006
Author(s):  
Maissa Abdallah ◽  
Nadine Abdallah ◽  
Maryline Chetto
Keyword(s):  
Sensor Networks ◽  
Embedded System ◽  
Sensor Nodes ◽  
Electronic Systems ◽  
Periodic Tasks ◽  
Energy Aware ◽  
Power Sources ◽  
Energy Harvesters ◽  
Aperiodic Tasks ◽  
Energy Constraints

Nowadays, wireless sensor networks (WSNs) are more and more used in applications such as environment monitoring, healthcare monitoring, etc...The challenge in sensor networks is to ensure the sustainability of the system by guaranteeing the required performance level. However, with the limited capacity of finite power sources and the need of guaranteeing a long lifetime of those systems, it is suitable to use energy harvesting which allows to supply low-power electronic systems by converting ambient energy into electric power. Hence, our study is concerned with the problem of soft periodic and aperiodic tasks scheduling in sensor nodes powered by energy harvesters. In this paper, we address this issue by proposing three energy-aware schedulers, namely BG-Green-RTO, BG-Green-BWP and Green-AWP which aim to improve the responsiveness of aperiodic tasks while still guaranteeing the execution of periodic tasks considering their timing and energy constraints. Such algorithms allow to gracefully cope with processing overload and energy starvation. Moreover, a simulation study permits to show their performance.

scholarly journals Hierarchical Scheduling for Real-Time Periodic Tasks in Symmetric Multiprocessing

2021 ◽  
Author(s):  
Tom Springer ◽  
Peiyi Zhao
Keyword(s):  
Real Time ◽  
Response Times ◽  
Periodic Tasks ◽  
Global Scheduling ◽  
Hierarchical Scheduling ◽  
Time Performance ◽  
Performance Guarantees ◽  
Partitioned Scheduling ◽  
Hard Real Time ◽  
Time Periodic

In this paper, we present a new hierarchical scheduling framework for periodic tasks in symmetric multiprocessor (SMP) platforms. Partitioned and global scheduling are the two main approaches used by SMP based systems where global scheduling is recommended for overall performance and partitioned scheduling is recommended for hard real-time performance. Our approach combines both the global and partitioned approaches of traditional SMP-based schedulers to provide hard real-time performance guarantees for critical tasks and improved response times for soft real-time tasks. Implemented as part of VxWorks, the results are confirmed using a real-time benchmark application, where response times were improved for soft real-time tasks while still providing hard real-time performance.

scholarly journals Scheduling an aperiodic flow within a real-time system using Fairness properties

2014 ◽  
Vol Volume 18, 2014 ◽  
Author(s):  
Annie Choquet-Geniet ◽  
Sadouanouan MALO
Keyword(s):  
Real Time ◽  
Acceptance Test ◽  
Periodic Tasks ◽  
Real Time System ◽  
Model Driven ◽  
Aperiodic Tasks ◽  
International Audience ◽  
Hard Real Time ◽  
Model Driven Approach ◽  
Time Systems

International audience We consider hard real-time systems composed of periodic tasks and of an aperiodic flow. Each task, either periodic or aperiodic, has a firm deadline. An aperiodic task is accepted within the system only if it can be completed before its deadline, without causing temporal failures for the periodic tasks or for the previously accepted aperiodic tasks. We propose an acceptance test, linear in the number of pending accepted aperiodic tasks. This protocol can be used provided the idle slots left by the periodic tasks are fairly distributed. We then propose a model-driven approach, based on Petri nets, to produce schedules with a fair distribution of the idle slots for systems of non independent periodic tasks. Nous considérons des systèmes temps-réel composés de tâches périodiques et d’un fluxapériodique. Toutes les tâches, périodiques comme apériodiques, sont soumises à des échéancesstrictes. Une tâche apériodique n’est acceptée que si elle ne remet pas en cause le respect deséchéances par les tâches périodiques et par les tâches apériodiques déjà acceptées. Nous proposonsun protocole d’acceptation des tâches apériodiques de complexité linéaire en le nombre de tâchesapériodiques acceptées présentes dans le système. Ce protocle est utilisable dès lors que les tempscreux sont répartis de manière équitable. Nous proposons donc une approche modèle, à base deréseaux de Petri, pour produire des séquences où les temps creux sont équitablement répartis, pourdes systèmes de tâches interdépendantes.

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