real-time task system

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Schedulability Test for Soft Real Time Systems under Multi processor Environment by using an Earliest Dead line First Scheduling Algorithm

Schedulability Test for Soft Real Time Systems under Multi processor Environment by using an Earliest Dead line First Scheduling Algorithm

guaranteeing a lower tardiness bound than Feasible EDF, we have so far not been able to derive a non-trivial bound under it. In fact, we conjecture that a severe restriction on total utilization may be necessary, in addition to per-task utilization restrictions, to guarantee a non-trivial tardiness bound under unrestricted EDF. We believe that such studies should be conducted regularly by collecting data continuously so that skill demand patterns can be understood properly. This understanding can lead to informed curricula design that can prepare graduates equipped with necessary skills for employment. Once such studies are carried out, students can use the findings to select courses that focus on those skills which are in demand. Academic institutions can use the findings so that those skills in demand can be taken into account during curriculum design. As an advance to our work, in future, we have desire to work on different deployment approaches by developing more strong and innovative algorithms to solve the time complexity of Earliest Deadline First. Moreover, as our proposed algorithm is a generalized one, we have planned to expand our idea in the field of Real Time System existing Rate Monotonic Algorithm for calculating minimum Time Complexity. Moreover, we have aim to explore some more methodologies to implement the concept of this paper in real world and also explore for Fault Tolerance Task Scheduling Algorithms to finding the Task Dependency in single processor or multiprocessor system for reducing the time for fault also reduce the risk for fault and damage.
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A Collaborative Real Time Drawing System  “Multi User Virtual Drawing Board”

A Collaborative Real Time Drawing System “Multi User Virtual Drawing Board”

Multi User Virtual Drawing Board is a collaborative real time system that allows users to perform collaborative task of drawing effectively and efficiently. The design of such a system uses many concepts of distributed system like message passing, synchronization, sending updates to other users. Synchronization is handled in this system in such a way that the various threads used to represent various processes occurring in the system allows the events to occur in a step by step manner. Resources are efficiently shared amongst all the users and no user finds problem while gaining access to any resource. It provides many other features apart from drawing like sending instant messages to other users, sending text to other users, allows to see users information currently logged in. Therefore, this type of a system is an integration of both chatting as well as drawing system. Thus, solving many purposes and finds application in wide variety of fields like cooperate offices, banks, chatting purposes or to share some important information to group of users.
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Direct real time neural evidence for task set inertia

Direct real time neural evidence for task set inertia

mastoids. Recording locations were based on the interna- tional 10-20 system (Jasper, 1958, appendix) and included midline (Fz, Cz, Pz), fronto-polar (Fp1/Fp2), frontal (F7/ F8, F5/F6, F3/F4), central (C7/C8, C5/C6, C3/C4), poste- rior (P7/P8, P5/P6, P3/P4), and occipital (O1/O2) sites. Vertical and horizontal eye movements were recorded from additional electrode pairs. EEG data were recorded at 167 Hz and referenced off-line to the average of the signal at the two mastoids. EEG and electrooculogram (EOG) data were recorded with a bandwidth from 0.03 to 40 Hz (−3 dB). Trials containing large EOG artifacts were rejected, as were trials containing analog-to-digital satu- ration or baseline drift exceeding ±80  µV. Other EOG blink artifacts were corrected using a linear regression estimate (Semlitsch, Anderer, Schuster, & Presslich, 1986). The researcher was blind to trial identity when process- ing EEG data. Procedures for the rejection of trials were set a priori and were based on standards we have adopted in previous work (e.g., Evans et al., 2010). Less than 5% of all trials were rejected because of EEG artifacts. The total epoch length was 1,536 ms with a 102-ms prestimu- lus baseline, relative to which all mean amplitude mea- sures were taken. A seven-point binomially weighted smoothing filter (~22 Hz) was applied prior to analysis.
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Scheduling in Real Time System

Scheduling in Real Time System

In 2017, R. Devaraj, A. Sarkar and S. Biswas, reported that in same year research was done on modeling of decision system. [10] In 2017 Fan, Ming, Qiushi Han, and Xiaokun Yang. reported that there is increase in transistors density on single processing chip due to increasing development of semiconductor technology. [29] In 2018 Chen, Huangke, et al. reported a research was on shedulability of tasks that are fault tolerant to increase reliability in clouds fault tolerance is too much important issue.[6] In 2018, Guo, Pengze, et al. reported that Existing scheduling approaches for dynamic workflow in cloud environment is inadequate that’s why a research on RT task in cloud environment was also done in same year[8].
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Fault Tolerant Energy Aware Task Scheduling on Multiprocessor System for Fixed Priority Real Time Tasks

Fault Tolerant Energy Aware Task Scheduling on Multiprocessor System for Fixed Priority Real Time Tasks

Abstract: Energy-aware real-time scheduling is gaining attention in recent years owing to environmental concerns and applications in numerous fields. System reliability also gets affected adversely with increasing energy dissipations posing serious challenges before the researchers. Keeping these in view, in recent times researchers have diverted to combining issues of fault-tolerance and energy efficiency. In literature, DVFS and DPM, most commonly used techniques for power management in task scheduling, are often combined with Primary/Backup technique to achieve fault tolerance against transient and permanent faults. Optimal algorithms, Earliest deadline first (EDF) and Rate-Monotonic (RM), meant for scheduling dynamic and fixed priority tasks respectively, have mainly been analyzed using a dual-processor approach for fault-tolerance and energy efficiency. In this paper, to handle higher workload of fixed-priority real-time tasks, energy-aware fault-tolerant scheduling algorithms are proposed for multiprocessor systems with balanced and unbalanced number of main and auxiliary processors. Simulations over extensive task-sets indicate that balanced approach is more energy-efficient than the unbalanced one.
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 EFFECT OF FATIGUE ON SSVEP DURING VIRTUAL WHEELCHAIR NAVIGATION

 EFFECT OF FATIGUE ON SSVEP DURING VIRTUAL WHEELCHAIR NAVIGATION

A. M. Franklin Richard and S. Sudheer Sukumaran Implemented an embedded platform for industrial automated system designed with multiple tasks. In order to manage the various tasks evaluated Priority based Preemptive Task Scheduling algorithm in µC/OS-II Real Time Operating System is used. In his paper Motor task is controlled by PI algorithm. When an interrupt is created, the corresponding task is executed and thus response is obtained in few microseconds the corresponding task output are displayed on the LCD. Consequently, with the sensor value, processing speed and timing constraints of the task scheduled, the automated system is functioning with rapid task execution context under multitasking environment [4].
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The multiprocessor real-time scheduling of general task systems

The multiprocessor real-time scheduling of general task systems

Real-time systems are designed to satisfy notions of temporal correctness and pre- dictability. In a real-time system, computations must occur by specified times. In our daily lives, we rely on systems that have underlying temporal constraints including avionic control systems, medical devices, network processors, digital video recording devices, and many other systems and devices. In each of these systems there is a po- tential penalty or consequence associated with the violation of a temporal constraint. For example, in a safety-critical system, a temporal violation can be life-threatening: a patient wearing an Implantable Cardioverter Defibrillator (ICD) is at risk of car- diac arrest if the device does not administer shocks to the heart in a timely fashion. In other (less critical) applications, violations of temporal constraints may result in a degradation in the quality-of-service experienced by the application user: a user listening to an MP3 file may experience audio jitter if the frames of the file are not decoded at a consistent rate. Regardless of the application, a well-designed real-time system should eliminate or minimize temporal constraint violations.
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Performance Analysis of Real Time Task Scheduling Algorithm

Performance Analysis of Real Time Task Scheduling Algorithm

Normally the systems in which periodic activities are take place schedule by fixed priority algorithm such as RM (Rate Monotonic) algorithm. In this algorithm the priority of the task is decided by the rate (period) of the task. The system in which the activities are usually changing used dynamic priority scheduling algorithm EDF (Earliest Deadline First). In this priority of the task is depends on its deadline. The RM scheduling algorithm is easy to implement, efficient and less complex. But sometimes it is not optimal for successful execution of entire tasks in Real Time system. In addition EDF algorithm is very successful in scheduling Real Time task without missing its deadline.
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Ego depletion in real-time: an examination of the sequential-task paradigm

Ego depletion in real-time: an examination of the sequential-task paradigm

In Study 5, we address these issues by first introducing an individual differences approach to explore performance on the letter-e task, and then adopt a similar methodology to explore carry-over effects. Here we adopt a distinction made by Healey et al. (2011) regarding extrinsic and intrinsic influences on task performance. Extrinsic factors are those that are external to the cognitive system under consideration, whereas intrinsic factors reflect internal changes to the cognitive system itself. Thus, comparing performance of participants who have to respond or not respond on a Letter-e task under a complex set of requirements, to participants who simply have to identify any letter e that they encounter, would reflect, external factors. However, the strength model assumes that performing the letter- e task produces internal intrinsic changes to the self-regulatory system, in that self-control resources become depleted. Moreover, as Healey et al. (2011) argue, even within a group that has been exposed to a demanding task there is going to be individual variation in some fundamental aspect of the relevant system, such that participants perform the task better than others, perhaps due to a better ability to control or regulate self-control resources. Thus, an individual difference approach to intrinsic depletion effects appears to be an alternative, and perhaps more appropriate, methodology for examining ego-depletion than the typical extrinsic control group vs. experimental group methodology that dominates current practice.
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ACO Based on EDF for Real Time Task Scheduling

ACO Based on EDF for Real Time Task Scheduling

In Kotecha’s algorithm, the switching criterion is depend on the result of executed jobs, in this theory during underload condition, EDF algorithm is used for reducing execution time and during overloaded condition ACO based scheduling algorithm is used for achieving better performance. However, the switching criterion is not clear and it is difficult to identify system’s condition. Moreover, when a task-set has a large numbers of tasks, the switching criterion will occur frequent switching bring unnecessary overhead of computation.

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ASSOCIATION RULE MINING BASED VIDEO CLASSIFIER WITH LATE ACCEPTANCE HILL 
CLIMBING APPROACH

ASSOCIATION RULE MINING BASED VIDEO CLASSIFIER WITH LATE ACCEPTANCE HILL CLIMBING APPROACH

Jaehwan Lee et al. put forward the concept of hardware real-time operating system (HRTOS) from the 1980s, and proposed to use specific hardware IP-kernel to realize RTOS scheduler after analysis and comparison of RTOS scheduler based on hardware and software implementation [2]. Task scheduling is the key of RTOS, communications among the tasks, external events processing and interrupt handling are all dependent on task scheduling. And with the improvement and enhancement of system functions, the relationship among tasks becomes more complex, and more peripherals need to be dealt with, all these require task scheduling continuously to participate in, causing the system performance and real-time response ability to decline sharply [3]. If task scheduling is implemented partly by hardware, it is no doubt that its performance can be improved greatly, thus the performance of the whole RTOS is improved accordingly [4].
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Static task partitioning for locked caches in multi-core real-time systems

Static task partitioning for locked caches in multi-core real-time systems

In this section, we describe our system architecture and assumptions to WCET analysis for this study. The objective of this work is to best utilize a private cache architecture. This corresponds to the current trend in potentially mesh or tile- based multi-core designs. Tile-based architectures consist of a large number tile processors (cores). Each tile consists of an in-order processor, a private L1, a private L2 cache and a router (see Figure 1). Each tile acts as a node on a mesh interconnect. Recent work has added Quality-of-Service (QoS) policies to mesh-interconnects [13]. We have identified these trends as the driving force for the simplification of our system. We assume an architecture that has private caches and has a QoS-based interconnect. We assume that the first level of cache allows a certain number of ways of the associative cache to be locked as shown in Figure 2. We also assume that the L2 caches are large enough with high associativity so that the address space of allocated hard real-time tasks on a core fit within the L2 cache. Thus, we assume that the off-chip references occur only
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Reducing the cost of real-time software through a cyclic task abstraction for Ada

Reducing the cost of real-time software through a cyclic task abstraction for Ada

A gap exists between the design and specification of tasks in a real-time system and their implementation in Ada. Predominately, these tasks are inherently cyclic in nature, yet Ada does not provide a simple way to express cyclic tasks and their properties. Furthermore, microcontroller-based real-time systems lack a suitable Ada executive or run-time with the capability to enforce cyclic task properties online, nor fully support the needs of real-time users. These observations resulted from experiences gained at the beginning of the doctorate, when the dissertation began as a study into the reliability of auton- omous scale helicopters. At the time a suitable autonomous platform was not readily or affordably available, necessitating its development for the thesis. While abandoned because of hardware issues, the software of the autonomous helicopter project inflicted a desire to address the observed weaknesses of cyclic tasks in Ada. Ada was chosen because, unlike other languages, Ada marks itself as a language aiding software engineering practises: facilitating the develop- ment of reliable and maintainable software by promoting the writing of clear, unambiguous and modular code, enforced to a specification (Moralee, 1981). Consequently, Ada minimises the life-cycle cost of software (Whitaker, 1993) and naturally befits a project where the software must be correct or people get hurt: a scale helicopter has all the inherent safety of an upside-down flying lawnmower.
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Java Based Real Time Programming - Free Computer, Programming, Mathematics, Technical Books, Lecture Notes and Tutorials

Java Based Real Time Programming - Free Computer, Programming, Mathematics, Technical Books, Lecture Notes and Tutorials

4. Do not use synchronized blocks , which are contradictory to proper object- oriented design of concurrent software and to the monitor concept as such. The reason for rule A is that the actions of a thread is defined via a method (run) which from a purely object-oriented point of view is a method like any other, with access to all attributes of the object. Mutual exclusion between the internal thread (executing the run method) and the external threads (calling the moni- tor methods) would require the run method to be synchronized as well. Another alternative could be to only access the attributes of the object via synchronized methods. However, the concurrency correctness would then heavily depend on programming discipline; neither the compiler nor the run-time system can com- plain about the run method accessing the attributes (run is nothing special from a language point of view). The public, protected, and private, keywords have to do with visibility between ordinary objects; they have nothing to do with concur- rency. In case of mixing threads and monitors we get no help from the compiler as when we use synchronized methods to access protected attributes. The lack of support for the Task abstraction could be considered as a deficiency of Java, but as will be argued later, the task is not a suitable abstraction for the design of object oriented concurrent (or real-time) systems anyway.
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Real-Time Big Data Analytics using Hadoop

Real-Time Big Data Analytics using Hadoop

Abstract-- Recent Technology have led to a large volume of data from different areas(ex. medical, aircraft, internet and banking transactions) from last few years. Big Data is the collection of this field’s information. Big Data contains high volume, velocity and high variety of data. For example Data in GB or PB which are in different form i.e. structured, unstructured and semi-structured data and its requires more fast processing or real-time processing. Such Real time data processing is not easy task to do, Because Big Data is large dataset of various kind of data and Hadoop system can only handle the volume and variety of data but for real-time analysis we need to handle volume, variety and the velocity of data. To solve or to achieve the high velocity of data we are using two popular technologies i.e. Apache Kafka, which is message broker system and Apache Storm, which is stream processing engine.
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Stochastic Analysis of a resource reservation system

Stochastic Analysis of a resource reservation system

Once interrupt handlers have been transformed into schedulable entities, the problem remains open of identifying the best scheduling algorithm that can be used to serve the newly introduced threads. For example, Manica et al. [54, 55] have provided a clear evidence that using resource reservations [5] to schedule the interrupt han- dlers (IRQ threads, in Preempt-RT) allows the designer to find ap- propriate trade-offs between the response time of real-time tasks and the device throughput (this is important when the device is used by real-time tasks). However, to the best of our knowledge, most ex- periments and tests with advanced scheduling solutions have been performed only using prototypical schedulers or experimental Oper- ating Systems [56, 43]. Only recently has a Linux scheduler based on resource-reservation has been proposed to the kernel community [57]. Such a scheduler exports an API that can be easily used to schedule kernel threads implementing the device drivers. Additionally, most of the previous work has focused on network devices [47, 48, 44, 51, 55] paying little or no attention to other types of devices (e.g., disks). Fi- nally, another limitation of previous results is that they are mostly collected on artificial task sets.
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Predictable Task Migration Support and Static Task Partitioning for
Scalable Multicore Real-Time Systems.

Predictable Task Migration Support and Static Task Partitioning for Scalable Multicore Real-Time Systems.

3. In Chapter 4, we further the concept of locked caches on scalable multicore architectures by analyzing its impact on static task partitioning algorithms. In shared cache architec- tures, a single resource is shared among all the tasks. The objective of task partitioning on a shared cache architecture is to reduce response time of tasks. With scalable archi- tectures, there are abundant computing and cache resources and the focus shifts toward efficiently utilizing computing resources. Also, in scalable cache architectures with pri- vate caches, conflicts exist only among the tasks scheduled on one core. This calls for a cache-aware allocation of tasks onto cores. Here, we propose a novel variant of the cache-unaware First Fit Decreasing (FFD) algorithm called the Naive locked First Fit Decreasing (NFFD) policy. We propose two cache-aware static scheduling schemes: (1) Greedy First Fit Decreasing (GFFD) and (2) Colored First Fit Decreasing (CoFFD) for task sets where tasks do not have intra-task conflicts among locked regions (Scenario A) [75]. NFFD is capable of scheduling high utilization task sets that FFD cannot schedule. Experiments also show that CoFFD consistently outperforms GFFD resulting in a lower number of cores and lower system utilization. For a more generic case where tasks have intra-task conflicts, we split task partitioning into two phases: task selection and task allocation (Scenario B) [76]. Instead of resolving conflicts at a global level, these algo- rithms resolve conflicts among regions while allocating a task onto a core and perform unlocking at the region level instead of the task level. We show that a combination of our novel Dynamic Ordering (task selection) with Chaitin’s Coloring (task allocation) scheme reduces the number of cores required considerably over a basic scheme (combina- tion of Monotone Ordering and Regional FFD). Regional unlocking allows this scheme to outperform CoFFD for medium utilization (0.40 > locked task utilization ≥ 0.25) task sets from Scenario A. However, CoFFD performs better than any other scheme for high utilization (0.55 > locked task utilization ≥ 0.40) task sets from Scenario A.
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Fuzzy Based Real Time Task Scheduling for Multiprocessor System.

Fuzzy Based Real Time Task Scheduling for Multiprocessor System.

Scheduling real time systems involves allocation of resources and CPU-time to tasks in such a way that certain performance requirements are met. In real time systems scheduling plays a more critical role than non-real-time systems because in these systems having the right answer too late is as bad as not having it at all [1]. Such a system must react to the requests within a fixed amount of time which is called deadline. Real-time tasks can be classified as periodic or a periodic. A periodic task is a kind of task that occurs at regular intervals, and a periodic task occurs unpredictably. The length of the time interval between the arrivals of two consecutive requests in a periodic task is called period.
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K Mean Clustering based Task Allocation Model for Distributed Real Time System

K Mean Clustering based Task Allocation Model for Distributed Real Time System

In this section, a task allocation model has been developed to find the optimal system cost so that system performance could be enhanced. Effective allocation of parallel applications’ tasks may increase the performance of the distributed system. Execution cost, inter task communication cost, memory required by each task and the task accommodation capacity of processor should be known for the allocation of tasks. Obtaining all such information of tasks and processors / nodes is beyond the scope of this paper. The clustering has been done at two levels in the model, one at initial stage by using k- mean algorithm and the second at the time of allocation. TMSV (Task& Memory Status Vector) data structure and TMSV‘s Collection proposed in [5] are being used to solve the problem in this paper.
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Multiobjective GA for Real Time Task Scheduling

Multiobjective GA for Real Time Task Scheduling

A new task scheduling algorithm is proposed in this paper. This algorithm is designed for nonpreemptive tasks in soft real-time multiprocessor system with the communication time between processors and the precedence relationship between tasks. The objective of proposed scheduling algorithm is to minimize the total tardiness and total number of processors used simultaneously. For these conflicting objectives, this paper combines Adaptive Weight Approach (AWA). From the numerical results, the results of the proposed moGA are better than that of other algorithms.
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