Preemption Overheads Research Articles

Cluster formation techniques for hierarchical real time tasks allocation on multiprocessor system

SummaryReal‐time systems are nowadays extensively used in most time‐critical embedded applications. The existing multiprocessor real‐time scheduling algorithms are based on partitioned and global scheduling approaches. The partitioned‐based algorithms suffer poor utilization bound, load balancing, not compatible for an open system environment, and the global scheduling approach faces problems like high scheduling, migration overhead. Cluster scheduling represents a hybrid scheduling approach which consists of a set of processors as clusters and tasks scheduled to each processor of clusters using a global scheduling approach. The different cluster formation heuristics are investigated for homogenous clusters. The main objective of this article is to propose task utilization‐based cluster formation and harmonic period aware task allocation for a hierarchical real‐time system on a multiprocessor platform. Tasks with high utilization, cluster size tune to a smaller value to achieve high utilization. Tasks with low utilization, the size of cluster tune to larger to reduce migration and scheduling overheads. Experimentation performed on multiprocessor real‐time simulator with a different set of tasks, multiprocessor system, different tasks utilization, and cluster size. Simulation results show that cluster base approach increases the number of tasks scheduled on a multiprocessor system, system utilization, and reduces response time, migration, and preemption overheads.

Cluster Based Real Time Scheduling for Distributed System

Real time tasks scheduling on a distributed system is a complex problem. The existing real time tasks scheduling techniques are primarily based on partitioned and global scheduling. In partitioned based scheduling the tasks are assigned on a dedicated processor. The advantages of partitioned based approach is existing uni-processor scheduling techniques can be used; no migration overheads but task assignment is NP hard problem and optimal utilization of processing nodes is not possible. In global scheduling all tasks are maintained in a single tasks queue and allocated to multiple processing nodes. The advantage of global scheduling is optimal utilization of processing nodes but suffer from high migration and preemption overheads. This paper proposed cluster based real time tasks scheduling on a distributed system which is a hybrid scheduling approach where processing nodes group into cluster and scheduling using global scheduling. The simulation result shows that the proposed scheduling increases the tasks acceptance ratio, resource utilization as compared to partitioned and global scheduling and reduces migration as well as preemption overheads.

Real Time Resource Scheduling Framework for Smart City

Smart City plays a vital role in social development. Real time scheduling of different tangible and intangible resource in distributed environment in smart is challenging problem. The different disaster management tasks smart city applications such as floods, earthquake, pandemic, fire, disaster relief, and control of hazardous area, major accidents, control of terrorism and other attacks require real time emergency resources scheduling. The existing techniques uses for smart city resource management are suffering from low resource utilization and high response time, migration and preemption overhead. This work paper presents cluster based real time resource scheduling framework for emergency situation in smart city. The edge computing resources are group into cluster. The proposed framework increases resources utilization and reduces response time, migration, preemption overheads. The emergency tasks are scheduled to these computing cluster are allow to migrate within the cluster to ensure to reduce migration, switching overhead, response time and increase resource utilization and success rate.

Real-Time Scheduling for Preventing Information Leakage with Preemption Overheads

Real-time systems (RTS) are characterized by tasks executing in a timely manner to meet its deadlines as a real-time constraint. Most studies of RTS have focused on these criteria as p ...

Research on run-time overhead of RM and improvement

The rate-monotonic (RM) algorithm is a classic fixed priority real-time scheduling algorithm. However, in most embedded real-time systems where the workload is composed of many tasks of high frequency and short execution time, the overheads from preemptions of the real-time operating system will lead to a low resource utilization rate if the RM algorithm is directly used. By studying the preemption relationship of the tasks scheduled by RM algorithm, a model of preemption overheads is established with task attributes, based on which the run-time preemption overheads of RM algorithm are reduced by optimizing the start time of the tasks in embedded real-time systems. Finally, the experimental results show the validity of the proposed strategy.

Perfecting preemption threshold scheduling for object-oriented real-time system design

In spite of the proliferation of object-oriented design methodologies in contemporary software development, their application to real-time embedded systems has been limited because of the practitioner's conservative attitude toward handling timing constraints. In fact, this conservative attitude is well-grounded because traditional priority-based scheduling techniques cannot be straightforwardly integrated into them. The automated implementation from the object-oriented real-time designs usually incurs a large number of tasks which, under traditional priority-based scheduling techniques, does not scale well due to excessive preemption overheads. Recently, preemption threshold scheduling was introduced to reduce run-time multi-tasking overhead while improving schedulability by exploiting non-preemptibility as much as possible. Unfortunately, the preemption threshold scheduling cannot be directly adopted into the object-oriented design methods due to the lack of real-time synchronization.In this paper, we present the essential basis of real-time synchronization for preemption threshold scheduling. Specifically, we integrate the priority inheritance protocol, the priority ceiling protocol, and the immediate inheritance protocol into preemption threshold scheduling. We also provide their schedulability analyses. Consequently, the integrated scheme, which minimizes worst-case context switches, is appropriate for the automated implementation of real-time object-oriented design models.