共查询到18条相似文献,搜索用时 156 毫秒
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目前研究单机实时系统的调度算法文章大多只能调度单一类型的任务。本文在PKSA算法的基础上,建立了一种混合型实时容错模型,提出一种调度算法不仅可以调度有容错需求的周期任务,同时也能够调度无容错需求的周期任务和非周期非实时任务,实现了调度混合型任务的目的。 相似文献
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目前研究单机实时系统的调度算法文章大多只能调度单一类型的任务。本文在PKSA算法的基础上,建立了一种混合型实时容错模型,提出一种调度算法不仅可以调度有容错需求的周期任务,同时也能够调度无容错需求的周期任务和非周期非实时任务,实现了调度混合型任务的目的。 相似文献
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实时系统的多任务调度 总被引:13,自引:2,他引:13
讨论了实时系统多任务的调度,对速率单调调度算法进行了改进,以便其能应用于具有非周期任务的实时系统,同时对系统的瞬时过载有一定的适应性。最后,给出了系统中任务可调度的条件。 相似文献
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在研究基于窗口约束(m,k)模型的实时系统的基础上,提出一种基于非重叠组合窗口约束的实时系统.通过对该实时系统的可调度性条件的研究,提出一种新的组合窗口约束(m,k)^的调度算法,该算法充分利用组合约束的特点,考虑本次调度对该窗口的可调度的影响来确定任务的优先级,并以此来提高任务的可调度性、减少组合窗口限制违例.仿真试验表明该算法在组合窗口约束的调度上,优于传统的独立比较两个约束确定优先级的调度算法. 相似文献
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讨论了在准实时环境下,包括准实时周期任务和准实时非周期任务在内的混合任务调度算法HTSF.HTSF算法是在满足周期任务(m,k)-firm 约束规范的前提下提高非周期任务可调度性,同时合理利用可用空闲时间,提高整个系统的服务质量.HTSF算法给出了非周期任务的可调度性分析方法,同时采用静态调度与动态调度相结合的方法调度周期任务和非周期任务.模拟测试结果显示,系统对非周期任务的接收率比同类相关算法的接收率高. 相似文献
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实时系统中传统调度方式的一种改进方法 总被引:2,自引:0,他引:2
介绍了在实时操作系统(RTOS)中两种典型的调度算法,速率单调调度(RMS)算法和最早死线优先(EDF)调度算法。指出了传统实时系统中调度机制的不足之处,给出一个通用调度框架模型(GSF)。该模型将调度器分成事务分派器和事务调度器两个部分,事务分派器根据任务的需求设置相应的属性,而事务调度器则根据任务的属性决定采用哪种调度算法。该模型使得调度更加灵活、有效。 相似文献
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This paper addresses the problem of scheduling aperiodic tasks in real-time systems. The proposed scheme combines the Earliest-Deadline-First algorithm for scheduling periodic tasks with the Deferrable Server approach for servicing aperiodic tasks. Necessary and sufficient conditions are derived for guaranteeing feasibility of a given periodic task set when a deferrable server is present. An analytic model is proposed for selecting the best feasible period and computation time of the server to minimize the mean response time of aperiodic tasks. An evaluation of the proposed model using a simulator indicates that the server parameters selected by the model result in mean response times that are close to the best mean response time determined by the simulator. 相似文献
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强实时环境下调度非周期任务的时限寻优方法 总被引:1,自引:0,他引:1
文章提出了强实时环境下调度弱时限非周期任务的时限寻优方法(DOA),该方法在保证周期任务和偶发性任务满足时限要求的前提下,使非周期任务的响应时间达到最优。它还可根据实时应用的需要对算法的执行性能和计算复杂度进行折衷调整。仿真实验表明,DOA与现有的动态调度算法相比,使非周期任务响应时间更短,同时它收敛快,额外开销小,计算复杂度低,实现方便,因此是强实时环境下对周期任务与非周期任务进行混合调度的一种较好的方法。 相似文献
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提高软非周期任务响应性能的调度算法 总被引:9,自引:0,他引:9
实时环境中常常既包含硬周期任务,又包含软非周期任务,引入一种改进软非周期实时任务响应时间的算法.已有的解决混合任务调度问题的方法都是基于速率单调(Rate Monotonic)策略的,其中从周期任务“挪用时间”的算法被证明优于其他所有算法.但是,速率单调算法限制了处理器的使用率,从而使周期任务的可“挪用”时间受到限制.最后期限驱动(Deadline Driven)策略DD可使潜在的处理器利用率达到100%.新算法正是在周期任务的调度中适当加入了DD策略,从而使非周期任务的响应时间得以缩短.仿真实验的结果表明,这种算法的性能优于已有的所有算法,而由它所带来的额外开销却不算很高. 相似文献
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Aperiodic task scheduling for Hard-Real-Time systems 总被引:22,自引:5,他引:17
A real-time system consists of both aperiodic and periodic tasks. Periodic tasks have regular arrival times and hard deadlines.
Aperiodic tasks have irregular arrival times and either soft or hard deadlines. In this article, we present a new algorithm,
the Sporadic Server algorithm, which greatly improves response times for soft deadline aperiodic tasks and can guarantee hard
deadlines for both periodic and aperiodic tasks. The operation of the Sporadic Server algorithm, its performance, and schedulability
analysis are discussed and compared with previously published aperiodic service algorithms. 相似文献
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Many industrial applications with real-time demands are composed of mixed sets of tasks with a variety of requirements. These
can be in the form of standard timing constraints, such as period and deadline, or complex, e.g., to express application specific
or nontemporal constraints, reliability, performance, etc. As many algorithms focus on specific sets of task types and constraints
only, system design has to focus on those supported by a particular algorithm, at the expense of the rest.
In this paper, we present a method to deal with a combination of mixed sets of tasks and constraints: periodic tasks with
complex and simple constraints, soft and firm aperiodic, and sporadic tasks. We propose the use of an offline scheduler to
manage complex timing and resource constraints of periodic tasks and transform these into a simple EDF model with start-times
and deadlines. At run-time, the execution of the offline scheduled tasks is flexibly shifted in order to allow for feasible
inclusion of dynamically arriving sporadic and aperiodic tasks. Sporadic tasks are guaranteed offline based on their worst-case
activation frequencies. At run-time, this pessimism is reduced by the online algorithm which uses the exact knowledge about
sporadic arrivals to reclaim resources and improve response times and acceptance of firm aperiodic tasks. 相似文献
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沈卓炜 《计算机工程与应用》2007,43(5):3-6
针对混合任务实时调度的需求和MUF算法的局限性,提出了一种长释放时间间隔优先的混合任务实时调度算法LRIF,该算法除了可对周期性硬实时任务提供调度保证外,同时还可确保非周期性软实时任务的可调度率。论文还提出了LRIF调度算法的可调度性分析方法,并讨论了LRIF调度算法的实现方法。 相似文献