Causes, Effects, and Consequences of Priority Inversion in Transaction Processing

2020 ◽  
pp. 1-13 ◽  
Author(s):  
Sarvesh Pandey ◽  
Udai Shanker
Keyword(s):  
Real Time ◽  
Transaction Processing ◽  
Priority Inversion ◽  
High Priority Task ◽  
Research Areas ◽  
Priority Task ◽  
Wide Range ◽  
System Resource ◽  
Research Questions ◽  
Time Systems

The problem of priority inversion occurs when a high priority task is required to wait for completion of some other task with low priority as a result of conflict in accessing the shared system resource(s). This problem is discussed by many researchers covering a wide range of research areas. Some of the key research areas are real-time operating systems, real-time systems, real-time databases, and distributed real-time databases. Irrespective of the application area, however, the problem lies with the fact that priority inversion can only be controlled with no method available to eliminate it entirely. In this chapter, the priority inversion-related scheduling issues and research efforts in this direction are discussed. Different approaches and their effectiveness to resolve this problem are analytically compared. Finally, major research accomplishments to date have been summarized and several unanswered research questions have also been listed.

System Resource Management for Distributed Real-Time Systems.

1995 ◽  
Author(s):  
Michael Davis ◽  
Elin L. Klaseen ◽  
Louis C. Schreier ◽  
Alan R. Downing ◽  
Jon Peha
Keyword(s):  
Resource Management ◽  
Real Time ◽  
Real Time Systems ◽  
System Resource ◽  
Time Systems

Synchronization Analysis for Hard Real-Time Multicore Systems

2012 ◽  
Vol 241-244 ◽  
pp. 2246-2252
Author(s):  
Mao Lin Yang ◽  
Hang Lei ◽  
Yong Liao ◽  
Lin Hui Hu
Keyword(s):  
Real Time ◽  
Multicore Processors ◽  
Real Time Systems ◽  
Response Time Analysis ◽  
Time Analysis ◽  
Priority Inversion ◽  
Simulation Results ◽  
Hard Real Time ◽  
Local Interference ◽  
Time Systems

Multicore processors are increasingly used in real-time embedded systems. Better utilization of hard real-time systems requires accurate scheduling and synchronization analysis. In this paper, we characterize the major synchronization penalties arising from partitioned fixed priority scheduling for hard real-time tasks on multicore platform, including transitive remote preemption, multiple remote blocking, and multiple priority inversions. Subsequently, we propose a new response time analysis by improving the approach to bound task blocking time. The key idea of this approach is to classify the total blocking time into (i) direct blocking, including local and remote blocking, and transitive remote preemption; and (ii) multiple local interference which is incurred by multiple priority inversion. Simulation results indicate that the proposed approach produces less pessimistic results in task blocking time, and better schedulability performance.

scholarly journals Facilitating Preemptive Hardware System Design Using Partial Reconfiguration Techniques

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Julio Dondo Gazzano ◽  
Fernando Rincon ◽  
Carlos Vaderrama ◽  
Felix Villanueva ◽  
Julian Caba ◽  
...  
Keyword(s):  
System Design ◽  
System Integration ◽  
Partial Reconfiguration ◽  
Real Time Systems ◽  
High Priority Task ◽  
Dynamically Reconfigurable ◽  
Hardware System ◽  
Priority Task ◽  
Time Systems ◽  
Remote Invocation

In FPGA-based control system design, partial reconfiguration is especially well suited to implement preemptive systems. In real-time systems, the deadline for critical task can compel the preemption of noncritical one. Besides, an asynchronous event can demand immediate attention and, then, force launching a reconfiguration process for high-priority task implementation. If the asynchronous event is previously scheduled, an explicit activation of the reconfiguration process is performed. If the event cannot be previously programmed, such as in dynamically scheduled systems, an implicit activation to the reconfiguration process is demanded. This paper provides a hardware-based approach to explicit and implicit activation of the partial reconfiguration process in dynamically reconfigurable SoCs and includes all the necessary tasks to cope with this issue. Furthermore, the reconfiguration service introduced in this work allows remote invocation of the reconfiguration process and then the remote integration of off-chip components. A model that offers component location transparency is also presented to enhance and facilitate system integration.

scholarly journals Performance analysis of real-time and general-purpose operating systems for path planning of the multi-robot systems

2022 ◽  
Vol 12 (1) ◽  
pp. 285
Author(s):  
Seçkin Canbaz ◽  
Gökhan Erdemir
Keyword(s):  
Path Planning ◽  
Real Time ◽  
Operating Systems ◽  
General Purpose ◽  
High Priority Task ◽  
Tracking Tasks ◽  
Priority Task ◽  
Robot Systems ◽  
Robotic Applications ◽  
Multi Robot

In general, modern operating systems can be divided into two essential parts, real-time operating systems (RTOS) and general-purpose operating systems (GPOS). The main difference between GPOS and RTOS is the system istime-critical or not. It means that; in GPOS, a high-priority thread cannot preempt a kernel call. But, in RTOS, a low-priority task is preempted by a high-priority task if necessary, even if it’s executing a kernel call. Most Linux distributions can be used as both GPOS and RTOS with kernel modifications. In this study, two Linux distributions, Ubuntu and Pardus, were analyzed and their performances were compared both as GPOS and RTOS for path planning of the multi-robot systems. Robot groups with different numbers of members were used to perform the path tracking tasks using both Ubuntu and Pardus as GPOS and RTOS. In this way, both the performance of two different Linux distributions in robotic applications were observed and compared in two forms, GPOS, and RTOS.

Synchronization-Aware Task Allocation Techniques for Preemption Control to Reduce Blocking Time in Multiprocessor Real-Time System

2020 ◽  
Vol 11 (4) ◽  
pp. 60-79
Author(s):  
Ajitesh Kumar ◽  
Sanjai Kumar Gupta
Keyword(s):  
Real Time ◽  
Task Completion ◽  
Real Time Systems ◽  
Time System ◽  
Real Time System ◽  
Priority Inversion ◽  
Context Switching ◽  
Optimal Approach ◽  
Result Analysis ◽  
Time Systems

Multiprocessor real-time systems receive a great deal of attention. For better utilization of multiprocessors in a real-time context, an optimal approach for scheduling, allocation, and synchronization is required. In this research, a novel heuristic synchronization-aware scheduling has been proposed to reduce the blocking delays in a critical section and also bound to minimize multiple priority inversion. The key idea of this technique is to assign the task set in the same processor that accesses a common shared resource and also access them for the longest period of time; thereby, the global sharing of resource transforms into local sharing. From simulation results, it was concluded that the duration of blocking overheads should be minimized up to 25% to 30% and context switching between processors also reduced up to 10% to 15%. On the basis of result analysis, schedulability, minimization of context switching, and reduced blocking time indicate that the proposed method outperforms the existing methods and does not affect the task completion time.

scholarly journals TEACHING DESIGN PATTERNS IN A REAL-TIME EMBEDDED SYSTEMS INTERFACING COURSE

2015 ◽  
Author(s):  
Witold Kinsner
Keyword(s):  
Embedded Systems ◽  
Real Time ◽  
Design Patterns ◽  
Wireless Systems ◽  
Real Time Systems ◽  
Wide Range ◽  
Teaching Design ◽  
Time Systems

This paper presents an overview of designpatterns for teaching an undergraduate course oninterfacing of microcontrollers, microprocessors andmicrocomputers for real-time systems. Such design patternsare useful because the course must cover a wide range oftopics for both wired and wireless systems, and is intendedfor a variety of microcontrollers. Without the patterns,teaching all the material from ground up might not befeasible.

Survey on Periodic Scheduling for Time-triggered Hard Real-time Systems

2021 ◽  
Vol 54 (1) ◽  
pp. 1-32
Author(s):  
Anna Minaeva ◽  
Zdeněk Hanzálek
Keyword(s):  
Real Time ◽  
Satisfiability Modulo Theories ◽  
Real Time Systems ◽  
Scheduling Problems ◽  
Periodic Tasks ◽  
Periodic Scheduling ◽  
Source Codes ◽  
Wide Range ◽  
Solution Methods ◽  
Time Systems

This survey covers the basic principles and related works addressing the time-triggered scheduling of periodic tasks with deadlines. The wide range of applications and the increasing complexity of modern real-time systems result in the continually growing interest in this topic. However, the articles in this field appear without systematic notation. To address it, we extend the three-field Graham notation to cover periodic scheduling. Moreover, we formally define three example periodic scheduling problems (PSPs) and provide straightforward implementations of these examples in the Satisfiability Modulo Theories formalism with source codes. Then, we present a summary of the complexity results containing existing polynomially solvable PSPs. We also provide an overview of simple state-of-the-art methods and tricks to solve the PSPs efficiently in terms of time. Next, we survey the existing works on PSP according to the resource environment: scheduling on a single resource, on parallel identical resources, and on dedicated resources. In the survey, we indicate which works propose solution methods for more general PSPs. Finally, we present related problems that are not periodic by nature to provide inspiration for the PSP solution.

Software Engineering for Real Time Systems

IEE Review ◽  
1992 ◽  
Vol 38 (3) ◽  
pp. 112
Author(s):  
Stuart Bennett
Keyword(s):  
Software Engineering ◽  
Real Time ◽  
Real Time Systems ◽  
Time Systems
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