• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.499-502
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• 2010

프로그램의 복잡화와 대규모프로그램의 등장으로 다중작업을 분할하여 소규모 단위의 Task로 나누고 각각의 Task를 우선순위에 따라 스케쥴링을 수행해야하는 요구가 점점 확대되고 있다. 또한, 프로그램 개발환경의 다양화로 인하여 프로그램을 구현하다 보면 다양한 환경 조건에 맞춰서 개발하게 된다. 예를 들어 Embedded 환경인지 Windows 환경인지에 따라 다르고 운용체제의 사용에 따라서도 제약사항을 가져오는 경우가 많다. 이에 개발환경과 운용체제에 의존적이지 않도록 다중작업 분할처리를 수행할 수 있는 적응형 스케쥴링 기법을 소개한다. 본 논문에서는 적응형 스케쥴링 기법에 적용된 알고리즘에 대한 설명과 구현 후 적용한 사례를 기반으로 한 내용을 다룬다.

• 정보처리학회논문지A
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• 제11A권7호
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• pp.521-528
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• 2004

본 논문에서는 버스 기반의 클러스터 구조에 적합한 새로운 태스크 스케줄링 기법을 소개하고, PC 클러스터에 구현하여 스케줄링 기법의 성능을 분석한다. 구현된 스케줄링 기법은 태스크 그래프를 입력으로 받아 PC 클러스터로 스케줄링하며, 휴리스틱을 사용하여 태스크를 선택적으로 중복함으로써 병렬연산시간을 단축한다. PC 클러스터는 리눅스 OS가 설치된 6대의 PC가 Gigabit Ethernet으로 연결되어 있다. 통신을 위해 TCP/IP 프로토콜을 사용하며, 메시지 교환을 위해 표준화된 병렬 프로그래밍 도구로 MPI를 사용한다. 실험을 한 결과 본 논문에서 소개한 스케줄링 기법이 비교 기법보다 병렬연산시간 측면에서 성능이 우수함을 확인하였다.

• 한국멀티미디어학회논문지
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• 제8권12호
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• pp.1589-1596
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• 2005

The imprecise real-time system provides flexibility in scheduling time-critical tasks. Most scheduling problems of satisfying both 0/1 constraint and timing constraints, while the total error is minimized, are NP complete when the optional tasks have arbitrary processing times. Liu suggested a reasonable strategy of scheduling tasks with the 0/1 constraint on uniprocessors for minimizing the total error. Song et al suggested a reasonable strategy of scheduling tasks with the 0/1 constraint on multiprocessors for minimizing the total error. But, these algorithms are all off-line algorithms. On the other hand, in the case of on line scheduling, Shih and Liu proposed the NORA algorithm which can find a schedule with the minimum total error for a task system consisting solely of on-line tasks that are ready upon arrival. But, for the task system with 0/1 constraint, it has not been known whether the NORA algorithm can be optimal or not in the sense that it guarantees all mandatory tasks are completed by their deadlines and the total error is minimized. So, this paper suggests an optimal algorithm to search minimum total error for the imprecise on-line real-time task system with 0/1 constraint. Furthermore, the proposed algorithm has the same complexity, O(N log N), as the NORA algorithm, where N is the number of tasks.

• Journal of Information Processing Systems
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• 제7권4호
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• pp.707-716
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• 2011

It is important that desktop grids should be able to aggressively deal with the dynamic properties that arise from the volatility and heterogeneity of resources. Therefore, it is required that task scheduling be able to positively consider the execution behavior that is characterized by an individual resource. In this paper, we implement a log analysis system with REST web services, which can analyze the execution behavior by utilizing the actual log data of desktop grid systems. To verify the log analysis system, we conducted simulations and showed that the resource group-based task scheduling, based on the analysis of the execution behavior, offers a faster turnaround time than the existing one even if few resources are used.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권9호
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• pp.4103-4121
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• 2018

Quality of Service (QoS) awareness is recognized as a key point for the success of Internet of Things (IOT).Realizing the full potential of the Internet of Things requires, a real-time task scheduling algorithm must be designed to meet the QoS need. In order to schedule tasks with diverse QoS requirements in cloud environment efficiently, we propose a task scheduling strategy based on dynamic priority and load balancing (DPLB) in this paper. The dynamic priority consisted of task value density and the urgency of the task execution, the priority is increased over time to insure that each task can be implemented in time. The scheduling decision variable is composed of time attractiveness considered earliest completion time (ECT) and load brightness considered load status information which by obtain from each virtual machine by topic-based publish/subscribe mechanism. Then sorting tasks by priority and first schedule the task with highest priority to the virtual machine in feasible VMs group which satisfy the QoS requirements of task with maximal. Finally, after this patch tasks are scheduled over, the task migration manager will start work to reduce the load balancing degree.The experimental results show that, compared with the Min-Min, Max-Min, WRR, GAs, and HBB-LB algorithm, the DPLB is more effective, it reduces the Makespan, balances the load of VMs, augments the success completed ratio of tasks before deadline and raises the profit of cloud service per second.

• IEIE Transactions on Smart Processing and Computing
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• 제2권6호
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• pp.367-372
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• 2013

Cloud computing technology has been developing at an increasing expansion rate. Today most of firms are using this technology, making improving the quality of service one of the most important issues. To achieve this, the system must operate efficiently with less idle time and without deteriorating the customer satisfaction. This paper focuses on enhancing the efficiency of a conventional Genetic Algorithm (GA) for task scheduling in cloud computing using Fuzzy Logic (FL). This study collected a group of task schedules and assessed the quality of each task schedule with the user expectation. The work iterates the best scheduling order genetic operations to make the optimal task schedule. General GA takes considerable time to find the correct scheduling order when all the fitness function parameters are the same. GA is an intuitive approach for solving problems because it covers all possible aspects of the problem. When this approach is combined with fuzzy logic (FL), it behaves like a human brain as a problem solver from an existing database (Memory). The present scheme compares GA with and without FL. Using FL, the proposed system at a 100, 400 and 1000 sample size*5 gave 70%, 57% and 47% better improvement in the task time compared to GA.

• ETRI Journal
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• 제44권5호
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• pp.746-758
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• 2022

This paper focuses on a mobile edge-computing-enabled heterogeneous network. A battery level-aware task-scheduling framework is proposed to improve the energy efficiency and prolong the operating hours of battery-powered mobile devices. The formulated optimization problem is a typical mixed-integer nonlinear programming problem. To solve this nondeterministic polynomial (NP)-hard problem, a decomposition-based task-scheduling algorithm is proposed. Using an alternating optimization technology, the original problem is divided into three subproblems. In the outer loop, task offloading decisions are yielded using a pruning search algorithm for the task offloading subproblem. In the inner loop, closed-form solutions for computational resource allocation subproblems are derived using the Lagrangian multiplier method. Then, it is proven that the transmitted power-allocation subproblem is a unimodal problem; this subproblem is solved using a gradient-based bisection search algorithm. The simulation results demonstrate that the proposed framework achieves better energy efficiency than other frameworks. Additionally, the impact of the battery level-aware scheme on the operating hours of battery-powered mobile devices is also investigated.

• Journal of Computing Science and Engineering
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• 제2권1호
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• pp.74-97
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• 2008

A scheduling policy or a schedulability test is defined to be sustainable if any task system determined to be schedulable remains so if it behaves "better" than mandated by its system specifications. We provide a formal definition of sustainability, and subject the concept to systematic analysis in the context of the uniprocessor scheduling of periodic and sporadic task systems. We argue that it is, in general, preferable engineering practice to use sustainable tests if possible, and classify common uniprocessor schedulability tests according to whether they are sustainable or not.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.324-329
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• 2000

Object of a real-time system, that performs exact information based on the real-time constraint. is required for an improvement of high reliability. The fault-tolerant task scheduling strategy of multiprocessor as using a distributed memory based on a hardware redundancy can be improved into a high reliability of the real-time system. Therefore, this paper is shown to analyze the reliability of the system by using the transfer parameter and make the modeling in reference to a minimization of the fault-tolerant task scheduling strategy which uses a percentage of task missing and deadline parameter based on optimization task size.

• 한국멀티미디어학회논문지
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• 제13권10호
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• pp.1423-1435
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• 2010

무선 센서 네트워크를 구성하는 센서 노드는 배터리 기반의 제한된 전원과 낮은 연산 능력의 초경량 마이크로프로세서, 그리고 제한된 크기의 메모리 자원 등과 같은 하드웨어 사양을 가지고 있다. 이와 같은 제약 사항에도 불구하고 무선 센서 노드는 센싱 데이터의 실시간 처리 및 데이터 송수신 작업을 동시에 병행할 수 있어야 한다. 이에 본 논문에서는 배터리 작동식의 무선 센서 노드를 위한 에너지 효율적인 실시간 태스크 스케줄링 기법을 제안하였다. 제안한 에너지 효율적인 실시간 스케줄링 가법은 태스크의 실제 실행시간이 최악 실행시간보다 작을 경우에 발생되는 태스크의 실행 여유시간을 이용하여, 마이크로프로세서의 동작 주파수를 조절하고 무선 센서 노드의 전력 소비를 줄인다. 제안한 기법의 동작을 시험한 결과, 효율적인 전력 소비를 제공함과 동시에 실시간 태스크의 마감시한이 보장됨을 확인하였다.