共查询到16条相似文献，搜索用时 904 毫秒
1.
何颖 《贵州教育学院学报》2013,(9):18-21
爆炸式增长的数据要求高效率地使用计算资源,Hadoop是解决大数据处理的一个方向,不过Ha-doop平台还处于发展中,很多地方还有待完善。对Hadoop自带的三种调度器的优缺点进行分析,针对希望区分和动态改变作业服务质量的情况提出了动态优先调度算法。实验结果表明动态优先调度算法能够在作业的运行中动态改变作业的优先级,在效率上也有所提升。 相似文献
2.
苏淑霞 《宁夏师范学院学报》2014,(6):66-70
减少调度过程中松弛度计算次数和任务切换次数,是改善实时系统周期性任务最低松弛度优先调度算法(LLF)性能的主要方法之一.基本的LLF算法只以任务松弛度为优先级来调度任务,使调度过程出现颠簸现象.根据LLF算法的基本思想,对其调度方法加以改进,通过减少任务切换次数来减少调度过程中的颠簸现象,从而提高了处理器的利用率,取得了较好的调度性能. 相似文献
3.
多媒体服务器需要一个实时磁盘调度算法来为实时流提供同步数据.传统的磁盘调度算法没有考虑磁盘请求的实时性,因此需要对传统的磁盘调度算法SCAN进行改进以使其能够应用于多媒体服务器的磁盘请求.本文提出一个新的实时磁盘调度DBA-SCAN(Dynamic-Bandwidth-Assignment-SCAN)算法,DBA-SCAN算法将实时流分为保证任务和可选任务.只有当一个流中的保证任务被满足时,接纳控制才会接纳这个流.DBA-SCAN采用一种积极策略在运行时动态回收未用的带宽.被回收的带宽被用于为可选任务或者更多的非实时任务服务.通过模拟实验对DBA-SCAN算法和SCAN算法进行对比,实验结果显示,DBA-SCAN明显为实时流提供了更好的质量,同时也大大缩短了非实时任务的响应时间. 相似文献
4.
洪艳伟 《乐山师范学院学报》2007,22(5):105-106
RTLinux是一个具有实时内核的Linux操作系统.很适合在其上实现各种实时调度算法,文章分析了RTLinux的工作原理和已实现的调度算法,分析了其不足,提出了用EFDF对其进行改进.并介绍了在RTLiux上如何实现可达截止期最早的调度算法.通过在RTLinux系统中的实现,证实了该算法的有效性. 相似文献
5.
在带空间限制的实时多处理器系统模型上,针对文献[8]提出的DDS并行模型算法的不足提出一种新的基于EDF的优先级驱动全局调度算法,该算法保证了重要任务的优先调度。对文献[8]及该文的算法进行了对比研究,从调度成功率以及资源利用率方面对比,此算法均优于文献[8]提出的算法。 相似文献
6.
调度算法是指根据系统的资源分配策略所规定的资源分配算法。本文从实现方法和实例验证两方面，对先来先服务调度算法、短作业优先调度算法、高优先级优先调度算法和高响应比优先调度算法四种作业调度算法进行比较和分析后得出，为什么批处理系统常采用的作业调度算法是先来先服务调度算法。 相似文献
7.
刘成斌 《忻州师范学院学报》2007,23(5):46-48
对于实时混合型任务调度,基于NP问题的分析研究,在分层中采用基于阈值的双优先级调度算法,该算法结合了抢占式与非抢占式调度算法的优点,可以提高任务集的调度成功率,并减少由于任务切换引起的系统开销。对阈值的分配是调度算法的核心。在基本优先级已知的条件下,基于回溯技术的阈值分配算法利用低端任务阈值单向影响高端任务最大响应时间的特性,可以在有限的时间内为任务集找出一组具有极大值特征的阈值。该组阈值可以将任务切换次数降至最低,使各队列能够将任务的分配达到一个利用率很好的程度。 相似文献
8.
王得利 《唐山师范学院学报》2011,33(2):55-57
控制系统中任务的调度不仅影响系统的资源利用率,而且影响系统的控制性能。首先分析了周期性实时任务,并给出了任务模型。基于此,采用了EDF调度算法。根据系统的性能指标与任务的采样周期的关系,采用粒子群算法对系统性能进行优化。仿真结果表明,这种算法是有效的。 相似文献
9.
调度算法是指根据系统的资源分配策略所规定的资源分配算法．本文详细地讨论了先来先服务调度算法、短作业优先调度算法、高优先级优先调度算法和高响应比优先调度算法等四种常用作业调度算法的基本思想,并结合实例对其进行了分析和评价． 相似文献
10.
不断增大的数据规模给Hadoop集群处理能力带来了挑战,而合理的作业调度方式与策略能够提高集群的运行效率。通过对Hadoop MapReduce的任务调度机制进行研究,设计了节点负载能力与动态优先级的计算方式,提出了一种动态优先级的负载均衡调度算法,并搭建小型Hadoop平台进行了实验分析。结果表明,该算法在集群负载均衡方面的效果要优于传统调度算法。 相似文献
11.
In this paper, a novel scheduling mechanism is proposed to handle the real-time overload problem by maximizing the cumulative values of three types of tasks: the soft, the hard and the imprecise tasks. The simulation results show that the performance of our presented mechanism in this paper is greatly improved, much better than that of the other three mechanisms: earliest deadline first (EDF), highest value first (HVF) and highest density first (HDF), under the same conditions of all nominal loads and task type proportions. 相似文献
12.
INTRODUCTION Traditionally, in real-time schedule theory,real-time requirements are classified into two types,hard real-time (HRT) and soft real-time (SRT)(Giorgio, 1997). HRT requirement is mainly util-ized in temporal safety-critical applications on thetemporal aspect of processing a task. For applica-tions with HRT requirement, such as process con-trol or manufacture automation, deadline miss isnot tolerated, i.e., each task of an HRT applicationmust meet its deadline, and ot… 相似文献
13.
(m,k)-firm real-time or weakly hard real-time(WHRT)guarantee is becoming attractive as it closes the gap between hard and soft(or probabilistic)real-time guarantee,and enables finer granularity of real-time QoS through adjusting m and k.For multiple streams with(m,k)-firm constraint sharing a single server,an on-line priority assignment policy based on the most recent k-length history of each stream called distance based priority(DBP)has been proposed to assign priority.In case of priority equality among these head-of-queue instances,Earliest Deadline First(EDF)is used.Under the context of WHRT schedule theory,DBP is the most popular,gets much attention and has many applications due to its straightforward priority assignment policy and easy implementation.However,DBP combined with EDF cannot always provide good performance,mainly because the initial DBP does not underline the rich information on deadline met/missed distribution,specially streams in various failure states which will travel different distances to restore success states.Considering how to effectively restore the success state of each individual stream from a failure state,an integrated DBP utilizing deadline met/missed distribution is proposed in this paper.Simulation results validated the performance improvement of this proposal. 相似文献
14.
An integrated DBP for streams with (<Emphasis Type="Italic">m,k</Emphasis>)-firm real-time guarantee
(m,k)-firm real-time or weakly hard real-time (WHRT) guarantee is becoming attractive as it closes the gap between hard and soft
(or probabilistic) real-time guarantee, and enables finer granularity of real-time QoS through adjustingm andk. For multiple streams with (m, k)-firm constraint sharing a single server, an, on-line priority assignment policy based on the most recentk-length history of each stream called distance based priority (DBP) has been proposed to assign priority. In case of priority
equality among these head-of-queue instances, Earliest Deadline First (EDF) is used. Under the context of WHRT schedule theory,
DBP is the most popular, gets much attention and has many applications due to its straightforward priority assignment policy
and easy implementation. However, DBP combined with EDF cannot always provide good performance, mainly because the initial,
DBP does not underline the rich information on deadline met/missed distribution, specially streams in various failure states
which will travel different distances to restore success states. Considering how to effectively restore the success state
of each individual stream from a failure state, an integrated DBP utilizing deadline met/missed distribution is proposed in
this paper. Simulation results validated the performance improvement of this proposal.
Project supported by the National Natural Science Foundation of China (No.60203030) and Advanced Research Program of France-China
(Nos. PRA S101-04, PRA S103-02) 相似文献
15.
In hard real-time systems, schedulability analysis is not only one of the important means of guaranteeing the timelines of embedded software but also one of the fundamental theories of applying other new techniques, such as energy savings and fault tolerance. However, most of the existing schedulability analysis methods assume that schedulers use preemptive scheduling or non-preemptive scheduling. In this paper, we present a schedulability analysis method, i.e., the worst-case hybrid scheduling （WCHS） algorithm, which considers the influence of release jitters of transactions and extends schedulability analysis theory to timing analysis of linear transactions under fixed priority hybrid scheduling. To the best of our knowledge, this method is the first one on timing analysis of linear transactions under hybrid scheduling. An example is employed to demonstrate the use of this method. Experiments show that this method has lower computational complexity while keeping correctness, and that hybrid scheduling has little influence on the average worst-case response time （WCRT）, but a negative impact on the schedulability of systems. 相似文献
16.
互联网技术的发展，硬件技术和通信技术的进步 共同加快了计算机领域前进的步伐。20世纪80年代 出现了并行计算，支持同步的算法、程序和体系结构相 继被开发。随后出现了分布计算，它要求各个处理机 之间能够协同计算，通过处理机间的通信共同解决问 题。网格计算技术的发展适 相似文献