• Title, Summary, Keyword: Deadline

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A Heuristic for Fleet Size and Mix Vehicle Routing Problem with Time Deadline (고객의 납기마감시간이 존재하는 이기종 차량경로문제의 발견적 해법)

  • Kang Chung-Sang;Lee Jun-Su
    • Journal of the Society of Korea Industrial and Systems Engineering
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    • v.28 no.2
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    • pp.8-17
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    • 2005
  • This paper dealt with a kind of heterogeneous vehicle routing problem with known demand and time deadline of customers. The customers are supposed to have one of tight deadline and loose deadline. The demand of customers with tight deadline must be fulfilled in the deadline. However, the late delivery is allowed to customers with loose deadline. That is, the paper suggests a model to minimize total acquisition cost, total travel distance and total violation time for a fleet size and mix vehicle routing problem with time deadline, and proposes a heuristic algorithm for the model. The proposed algorithm consists of two phases, i.e. generation of an initial solution and improvement of the current solution. An initial solution is generated based on a modified insertion heuristic and iterative Improvement procedure is accomplished using neighborhood generation methods such as swap and reallocation. The proposed algorithm is evaluated using a well known numerical example.

A Real-Time Scheduling Algorithm for Tasks with Shared Resources on Multiprocessor Systems (다중프로세서 시스템상의 공유 자원을 포함하는 태스크를 위한 실시간 스케줄링 알고리즘)

  • Lee, Sang-Tae;Kim, Young-Seok
    • The KIPS Transactions:PartA
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    • v.17A no.6
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    • pp.259-264
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    • 2010
  • In case of scheduling tasks with shared resources in multiprocessor systems, Global Earliest Deadline First (GEDF) algorithm, equally applied Earliest Deadline First (EDF) which runs scheduling with deadline criterion, makes schedulability decline because GEDF typically does not have a specific process in order to handle tasks with shared resources. In this paper, we propose Earliest Deadline First with Partitioning (EDFP) for tasks with shared resources which partitions a task into two kinds of subtasks that include critical sections to access to shared resources, gives their own deadline respectively and manages them. As a result of simulations, EDFP shows better performance than GEDF for tasks with shared resources since system load goes up and the number of processor increases.

A Priority Scheme for IEEE 802.11 Wireless LAN

  • Jang, Yeong-Min
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.12B
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    • pp.1996-2002
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    • 2000
  • This paper investigates a priority scheme for IEEE 802.11 Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol in order to provide short access times for priority frames (e.g. time-deadline traffic) even when the overall traffic on the wireless channel is heavy. Under the compatibility constraint for the IEEE 802.11 wireless LANs, two priority systems are simulated: no priority (current IEEE 802.11 standard) for time-deadline traffics and dynamic time-deadline priority. We evaluate algorithms to improve the time-deadline traffic performance using discrete event simulation (DES)

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Managing Deadline-constrained Bag-of-Tasks Jobs on Hybrid Clouds with Closest Deadline First Scheduling

  • Wang, Bo;Song, Ying;Sun, Yuzhong;Liu, Jun
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.7
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    • pp.2952-2971
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    • 2016
  • Outsourcing jobs to a public cloud is a cost-effective way to address the problem of satisfying the peak resource demand when the local cloud has insufficient resources. In this paper, we studied the management of deadline-constrained bag-of-tasks jobs on hybrid clouds. We presented a binary nonlinear programming (BNP) problem to model the hybrid cloud management which minimizes rent cost from the public cloud while completes the jobs within their respective deadlines. To solve this BNP problem in polynomial time, we proposed a heuristic algorithm. The main idea is assigning the task closest to its deadline to current core until the core cannot finish any task within its deadline. When there is no available core, the algorithm adds an available physical machine (PM) with most capacity or rents a new virtual machine (VM) with highest cost-performance ratio. As there may be a workload imbalance between/among cores on a PM/VM after task assigning, we propose a task reassigning algorithm to balance them. Extensive experimental results show that our heuristic algorithm saves 16.2%-76% rent cost and improves 47.3%-182.8% resource utilizations satisfying deadline constraints, compared with first fit decreasing algorithm, and that our task reassigning algorithm improves the makespan of tasks up to 47.6%.

Timing Optimization of Real-Time System Design for Embedded Systems (Embedded System Design을 위한 Real-Time System의 최적화된 Timing효과의 구현)

  • Park, Eun-Jung;Jeong, Tai-Kyeong
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.3
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    • pp.564-570
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    • 2006
  • This paper presents a new real-time system design methodology for embedded system as well as event-driven real time application. It is required to implement a deadline handling mechanism in order to satisfy a large-scale distributed real time application. When we design real time system, it has handled a deadline and is important to measure / control a timing issue. These timing constraints usually associated with an interface between model and system. There are many case tools that supporting a real time application, for example, UML, graphic language for designing real time system, but they cannot provide efficient way to handle deadline miss. Therefore, users have to design deadline handler manually when they need to use it. This paper contributes solving the problems of user-level deadline handling for an embedded system. Also, it also discusses an efficient deadline handler design mechanism using on RoseRT, which is a graphical CASE tool supporting from UML.

Two-level Scheduling for Soft Real-Time Systems (소프트 실시간 시스템을 위한 두 단계 스케쥴링 알고리즘)

  • Kim, Jae-Hun
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.2
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    • pp.467-475
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    • 1999
  • This paper presents an algorithm for scheduling jobs in soft real-time systems. To simplify the scheduling for soft real-time systems, we introduce two-level deadline scheme. Each job in the system has two deadlines, which we call first-level and second-level deadlines, respectively. The first-level deadline is the same as the deadline in traditional real-time systems. The second-level deadline is later than the first-level deadline, and defines the latest point in time when the result is still acceptable. Partial-credit is given for jobs meeting the second-level deadline but missing the first-level deadline, whereas jobs meeting the latter are given full credit. We heuristically compute priorities of jobs in a dynamic way by combining the first-level adn second-level deadlines with the partial-credit. Simulation results indicate that our two-level scheduling algorithm is a viable approach for dealing with both soft real-time systems and temporary overloaded hard real-time systems.

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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.

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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A Guaranteed Real-time Scheduling Algorithm for (m,k)-firm Deadlines Constrained Tasks on Multiprocessors (멀티프로세서에서 (m, k)-firm Deadline 을 가지는 태스크를 위한 실시간 스케줄링 알고리즘)

  • Kong, Yeonhwa;Cho, Hyeonjoong
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.1529-1532
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    • 2010
  • 본 논문은 동종의 멀티코어에서 (m,k)-firm Deadline 을 가지는 태스크를 위한 실시간 시스템의 스케줄링 기법을 제안한다. 본 논문에서 제안된 알고리즘의 목적은 (m, k)-firm Deadline 을 만족시키는 확률을 증가시켜 최대의 Quality of Service 를 제공하는 것이다. 본 논문에서는 제안된 알고리즘이 QoS 를 보장함을 분석적으로 보이고 실험을 통해 알고리즘의 효율성을 검증한다.

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Development of an Extended EDS(Earliest Deadline Scheduling) Algorithm for the CAN-Based Real-Time System (CAN기반 실시간 시스템을 위한 확장된 EDS 알고리즘 개발)

  • Lee, Byong-Hoon;Kim, Hong-Ryeol;Kim , Dae-Won
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.51 no.7
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    • pp.294-301
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    • 2002
  • A new dynamic scheduling algorithm is proposed for CAN-based real-time system in this paper. The proposed algorithm is extended from an existing EDS(Earliest Deadline Scheduling) approach having a solution to the priority inversion. Using the proposed algorithm, the available bandwidth of network media can be checked dynamically, and consequently arbitration delay causing the miss of deadline can be avoided. Also, non-real time messages can be processed with their bandwidth allocation. Full network utilization and real-time transmission feasibility can be achieved through the algorithm. To evaluate the performance of algorithm, two simulation tests are performed. The first one is transmission data measurement per minute for periodic messages and the second one is feasibility in the system with both periodic messages and non-real time message.