scholarly journals AN INTELLIGENT SCHEDULER APPROACH TO MULTIPROCESSOR SCHEDULING OF APERIODIC TASKS

2012 ◽  
pp. 42-46
Author(s):  
INDURAJ. P. R
Keyword(s):  
Real Time ◽  
Prior Knowledge ◽  
Resource Availability ◽  
Execution Time ◽  
Arrival Time ◽  
Multiprocessor Scheduling ◽  
Multiprocessor System ◽  
Aperiodic Tasks

This paper presents a new scheduler capable of scheduling aperiodic tasks at real time in multiprocessor system. The algorithm proposes a new way to determine dynamically tasks of high priority and low priority finding the elapsed execution time and remaining execution time, and the amount of resource availability and deadline of task, with no prior knowledge of task arrival time and also ensures that no processor remains ideal thus utilizing processors at all times.

scholarly journals Optimizing Distributed Real-Time Embedded System Handling Dependence and Several Strict Periodicity Constraints

2011 ◽  
Vol 2011 ◽  
pp. 1-19 ◽  
Author(s):  
Omar Kermia
Keyword(s):  
Embedded System ◽  
Real Time ◽  
Execution Time ◽  
Decision Problem ◽  
Schedulability Analysis ◽  
Multiprocessor Scheduling ◽  
Np Hard ◽  
Necessary And Sufficient

This paper focuses on real-time nonpreemptive multiprocessor scheduling with precedence and strict periodicity constraints. Since this problem is NP-hard, there exist several approaches to resolve it. In addition, because of periodicity constraints our problem stands for a decision problem which consists in determining if, a solution exists or not. Therefore, the first criterion on which the proposed heuristic is evaluated is its schedulability. Then, the second criterion on which the proposed heuristic is evaluated is its execution time. Hence, we performed a schedulability analysis which leads to a necessary and sufficient schedulability condition for determining whether a task satisfies its precedence and periodicity constraints on a processor where others tasks have already been scheduled. We also present two multiperiodic applications.

scholarly journals Online Slack-Stealing Scheduling with Modified laEDF in Real-Time Systems

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1286 ◽  
Author(s):  
Wonbo Jeon ◽  
Wonsop Kim ◽  
Heoncheol Lee ◽  
Cheol-Hoon Lee
Keyword(s):  
Response Time ◽  
Real Time ◽  
Execution Time ◽  
Computation Method ◽  
Periodic Tasks ◽  
Worst Case ◽  
Dynamic Priority ◽  
Look Ahead ◽  
Aperiodic Tasks ◽  
Hard Real Time

In hard real-time task systems where periodic and aperiodic tasks coexist, the object of task scheduling is to reduce the response time of the aperiodic tasks while meeting the deadline of periodic tasks. Total bandwidth server (TBS) and advanced TBS (ATBS) are used in dynamic priority systems. However, these methods are not optimal solutions because they use the worst-case execution time (WCET) or the estimation value of the actual execution time of the aperiodic tasks. This paper presents an online slack-stealing algorithm called SSML that can make significant response time reducing by modification of look-ahead earliest deadline first (laEDF) algorithm as the slack computation method. While the conventional slack-stealing method has a disadvantage that the slack amount of each frame must be calculated in advance, SSML calculates the slack when aperiodic tasks arrive. Our simulation results show that SSML outperforms the existing TBS based algorithms when the periodic task utilization is higher than 60%. Compared to ATBS with virtual release advancing (VRA), the proposed algorithm can reduce the response time up to about 75%. The performance advantage becomes much larger as the utilization increases. Moreover, it shows a small performance variation of response time for various task environments.

scholarly journals Indoor Path-Planning Algorithm for UAV-Based Contact Inspection

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 642
Author(s):  
Luis Miguel González de Santos ◽  
Ernesto Frías Nores ◽  
Joaquín Martínez Sánchez ◽  
Higinio González Jorge
Keyword(s):  
Path Planning ◽  
Real Time ◽  
Execution Time ◽  
Point Cloud ◽  
Indoor Environments ◽  
Calculation Algorithm ◽  
Time Restrictions ◽  
Planning Algorithm ◽  
Inspection Tasks ◽  
Path Planning Algorithm

Nowadays, unmanned aerial vehicles (UAVs) are extensively used for multiple purposes, such as infrastructure inspections or surveillance. This paper presents a real-time path planning algorithm in indoor environments designed to perform contact inspection tasks using UAVs. The only input used by this algorithm is the point cloud of the building where the UAV is going to navigate. The algorithm is divided into two main parts. The first one is the pre-processing algorithm that processes the point cloud, segmenting it into rooms and discretizing each room. The second part is the path planning algorithm that has to be executed in real time. In this way, all the computational load is in the first step, which is pre-processed, making the path calculation algorithm faster. The method has been tested in different buildings, measuring the execution time for different paths calculations. As can be seen in the results section, the developed algorithm is able to calculate a new path in 8–9 milliseconds. The developed algorithm fulfils the execution time restrictions, and it has proven to be reliable for route calculation.

Calculating the maximum execution time of real-time programs

1989 ◽  
Vol 1 (2) ◽  
pp. 159-176 ◽  
Author(s):  
P. Puschner ◽  
Ch. Koza
Keyword(s):  
Real Time ◽  
Execution Time
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