• Title, Summary, Keyword: Deadline Monotonic

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Performance Evaluation of ISA100.11a Superframe Using Deadline Monotonic Scheduling (마감 단조 스케줄링을 사용한 ISA100.11a 슈퍼프레임 성능평가)

  • Saputra, Oka Danil;Shin, Soo Young
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39C no.12
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    • pp.1338-1345
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    • 2014
  • Recently, wireless technology gains attention for industrial networks due to low cost, flexibility, relatively easy installation and most importantly, solving the rouring issue. ISA100.11a is one of promising standard for wireless industrial networks (WINs). Data traffic in industrial networks are known to be periodic and must satisfy the real-time property namely deadline. Therefore, in this paper, we proposed to apply deadline monotonic scheduling to periodic tasks in ISA100.11a networks and to evaluate the performance of ISA100.11a by checking the schedulability and beacon frame overhead. Simulation results showns, that our proposed scheme can reduces the network overhead while maintaining schedulability as compared to the previous algorithm. In addition, by reducing the network overhead, our proposed scheme can send more data without degrading the overall performance of WINs.

Development of an Extended EDS Algorithm for CAN-based Real-Time System (CAN기반 실시간 시스템을 위한 확장된 EDS 알고리즘 개발)

  • Lee, Byong-Hoon;Kim, Dae-Won;Kim, Hong-Ryeol
    • Proceedings of the KIEE Conference
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    • pp.2369-2373
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    • 2001
  • Usually the static scheduling algorithms such as DMS (Deadline Monotonic Scheduling) or RMS(Rate Monotonic Scheduling) are used for CAN scheduling due to its ease with implementation. However, due to their inherently low utilization of network media, some dynamic scheduling approaches have been studied to enhance the utilization. In case of dynamic scheduling algorithms, two considerations are needed. The one is a priority inversion due to rough deadline encoding into stricted arbitration fields of CAN. The other is an arbitration delay due to the non-preemptive feature of CAN. In this paper, an extended algorithm is proposed from an existing EDS(Earliest Deadline Scheduling) approach of CAN scheduling algorithm haying a solution to the priority inversion. In the proposed algorithm, the available bandwidth of network media can be checked dynamically by all nodes. Through the algorithm, arbitration delay causing the miss of their deadline can be avoided in advance. Also non real-time messages can be processed with their bandwidth allocation. The proposed algorithm can achieve full network utilization and enhance aperiodic responsiveness, still guaranteeing the transmission of periodic messages.

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Development of an Extended EDS Algorithm for CAN-based Real-Time System

  • Lee, Byong-Hoon;Kim, Dae-Won;Kim, Hong-Ryeol
    • 제어로봇시스템학회:학술대회논문집
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    • pp.60.3-60
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    • 2001
  • Usually the static scheduling algorithms such as DMS(Deadline Monotonic Scheduling) or RMS(Rate Monotonic Scheduling) are used for CAN scheduling due to its ease with implementation. However, due to their inherently low utilization of network media, some dynamic scheduling approaches have been studied to enhance the utilization. In case of dynamic scheduling algorithms, two considerations are needed. The one is a priority inversion due to rough deadline encoding into stricted arbitration fields of CAN. The other is an arbitration delay due to the non-preemptive feature of CAN. In this paper, an extended algorithm is proposed from an existing EDS(Earliest Deadline Scheduling) approach of CAN scheduling algorithm having a solution to the priority inverstion ....

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An Exact Stochastic Analysis Method for Priority-driven Real-time Systems (우선순위 스케줄링을 사용하는 실시간 시스템을 위한 정확한 확률적 분석 방법)

  • 김강희
    • Journal of KIISE:Computer Systems and Theory
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    • v.31 no.3_4
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    • pp.170-186
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    • 2004
  • Recently, for real-time applications such as multimedia and signal processing, it becomes increasingly important to provide a probabilistic guarantee that each task in the application meets its deadline with a given probability. To provide the probabilistic guarantee, an analysis method is needed that can accurately predict the deadline miss probability for each task in a given system. This paper proposes a stochastic analysis method for real-time systems that use priority-driven scheduling, such as Rate Monotonic and Earliest Deadline First, in order to accurately compute the deadline miss probability of each task in the system. The proposed method accurately computes the response time distributions for tasks with arbitrary execution time distributions, and thus makes it possible to determine the deadline miss probability of individual tasks. In the paper. through experiments, we show that the proposed method is highly accurate and outperforms exisiting methods proposed in the literature.

A Message Schedulability Analysis using an Improved EDF Scheduling for Distributed Real-Time Systems (분산 실시간 시스템에서 개선된 EDF 정책을 사용한 메시지 스케줄가능성 분석)

  • Lee, Eun-Mi;Heu, Shin
    • Journal of KIISE:Computer Systems and Theory
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    • v.29 no.9
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    • pp.520-529
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    • 2002
  • This paper presents an approach for scheduling network messages with real-time dynamic algorithms. We present the method that calculates an intermediate relative deadline of the message based on the EDF(Earliest Deadline First) scheduling policy. We adjust the slack of message by using this intermediate relative deadline to allocate a priority of message. The priority of the message can be determined accurately by using the slack that calculates in our approach, which increases the schedulability efficiency of the message. As a result, we reduce the worst-case response time and improve the guarantee ratio of real-time messages. Also, we describe the analysis method to check the schedulability on message sets, and show the efficiency of our approach by comparing the results of the DM(Deadline Monotonic) approach and the existing EDF approach with that of the improved EDF in our approach through the simulation.

Optimal Checkpoint Placement for Real-Time Systems with Multi-Tasks Having Deadlines Longer Than Periods (데드라인이 주기보다 긴 멀티 태스크를 가진 실시간 시스템을 위한 최적 체크포인트 배치)

  • Kwak, Seong-Woo;Yang, Jung-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.1
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    • pp.148-154
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    • 2012
  • For a successful checkpointing strategy, we should place checkpoints so as to optimize fault-tolerance capability of real-time systems. This paper presents a novel scheme of checkpoint placement for real-time systems with periodic multi-tasks. Under the influence of transient faults, multi-tasks are scheduled by the Rate Monotonic (RM) algorithm. The optimal checkpoint intervals are derived to maximize the probability of task completion. In particular, this paper is concerned about the general case that the deadline of a task is longer than the period. Compared with the special condition that the deadline is equal to or less than the period, this general case causes a more complicate test procedure for schedulability of the RM algorithm with respect to a given set of checkpoint re-execution vectors. The probability of task completion is also derived in a more complex form. A case study is given to show the applicability of the proposed scheme.

Schedulability Test using task utilization in Real-Time system (실시간 시스템에서 태스크 이용율을 이용한 스케줄링 가능성 검사)

  • Lim Kyung-Hyun;Seo Jae-Hyeon;Park Kyung-Woo
    • Journal of Internet Computing and Services
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    • v.6 no.2
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    • pp.25-35
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    • 2005
  • The Rate Monotonic(RM) scheduling algorithm and Earliest Deadline First(EDF) scheduling algorithm are normally used in Real-Time scheduling algorithm. In those scheduling algorithm, we could predict the performance possibility with total utilization value of task group. But. it had problems with prediction of the boundedness in individual task when the utilization value was over in temporary task. In this paper, the suggested scheduling algorithm can predict task when the utilization value was over and it suggested the method of predicting scheduling possibility based on the utilization value of individual task as well. it predicted the boundedness of scheduling possibility test through simulation In Real-Time scheduling algorithm and analyzed the result.

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Rate-Monotonic Scheduler with Extended Schedulability Inspection for Hard Real-Time Tesk (경성 실시간 태스크를 위한 확장된 스케줄 가능성 검사를 갖는 비율단조 스케줄러)

  • 신동헌;조수현;김영학;김태형
    • The Journal of the Korea Contents Association
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    • v.4 no.2
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    • pp.50-60
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    • 2004
  • Recently, most of the embedded system is required not only many functions but also real-time characteristics in purpose. In the hard real-time system, especially, strict deadline of periodic task can affect the performance of the system. In this paper, we design and implement the scheduler based on RM(Rate-Monotonic) rule. This scheduler makes feasible patterns based on EDF(Earliest deadline first) rule with extended schedulability inspection before execution, for periodic task-set that has high CPU utilization and then, execute periodic task-set depended on feasible patterns. The feasible pattern formed into EDF rule is capable of the efficiency of CPU up to 100 percentage and by the referenced execution of the feasible pattern is possible of removing the red-time scheduling overhead that is the defect of the order of dynamic assignment rule.

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The Scheduling Technique Based on Rate-Monotonic with Extended Schedulability Inspection for Periodic Task in Hard Real-Time System (경성 실시간 태스크를 위한 확장된 가능성 검사를 통한 비율단조 기반 스케줄링 기법)

  • 신동헌;이준택;조수현;김영학
    • Proceedings of the Korean Information Science Society Conference
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    • pp.202-204
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    • 2003
  • 경성 실시간 시스템(Hard Real-Time System)어서는 주기 태스크들의 엄격한 마감시간(Deadline) 보장이 시스템의 성능을 좌우한다. 본 논문에서는 CPU의 이용률(Utilization)이 높아 비율단조 정책으로는 마감시간을 보장 할 수 없는 주기 태스크들을 위해 확장된 스케줄 가능성 검사를 통해 수행할 태스크들의 공통 주기(L.C.M : Least Common Multiple)내에서 EDF(Earliest-Deadline First) 정책을 기반으로 마감시간 보장 수행패턴(Feasible Pattern)을 찾고, 이를 참조하여 우선순위를 고려하지 않고 태스크들을 강제 수행할 수 있게 하는 비율단조 기반의 스케쥴링 기법을 제안한다. EDF를 기반으로 생성된 패턴은 EDF 정책의 특성에 따라 CPU의 이용률을 100% 까지 가능하게 하며 패턴을 참조하여 강제 수행함으로써 EDF 정책이 갖는 실행시간 스케쥴링 오버헤드를 없앨 수 있다.

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Peformance Analysis of Scheduler Selection based Real-time Linux Systems (스케줄러 선택기반의 실시간 리눅스의 성능분석)

  • Kang, Min-Goo
    • Journal of Internet Computing and Services
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    • v.8 no.1
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    • pp.71-78
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    • 2007
  • In this paper, an effective task scheduling scheme was proposed for the flexible real time LINUX systems with the selection between EDF(earliest deadline first) and RMS(rate monotonic scheduling). It was known that many task scheduling schemes were analyzed according to the characteristics of scheduling schemes and the guarantee of an earliest deadline scheduler for process utilities.

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