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1.
王涛  刘大昕 《计算机应用》2006,26(9):2217-2221
通过对单调速率任务分配算法调度策略和可调度条件的分析,在多处理器周期任务抢占调度模型基础上,细致刻画了任务分配算法如何分配任务的行为。依据Liu和Layland定理,给出多处理器下任务分配算法的最小RM利用率界的定理。仿真结果表明,分配算法的利用率界是不同特征任务集选择不同分配算法进行任务划分的关键,通过对任务集总利用率与算法利用率界的比较,判断使用该算法对任务集是否可以产生可行分配。  相似文献   

2.
针对时空众包任务分配研究中单一考虑任务分配总效用或任务等待时间,导致总体分配效果不佳的问题,提出一种基于分配时间因子的动态阈值算法。首先,基于预估等待分配时间和已等待分配时间计算任务的分配时间因子;其次,综合考虑任务的回报值和分配时间因子进行任务分配排序;然后,在初始值的基础上增加动态调整项为每一项任务设置阈值;最后,根据阈值条件为每一项任务设置候选匹配集,并从候选匹配集中选择匹配系数最大的候选匹配对加入结果集,完成任务分配。通过实验证明,该算法在任务分配率达到95.8%的情况下,与贪心算法相比,在分配总效用方面提升20.4%;与随机阈值算法相比,在分配总效用方面提升17.8%,在任务平均等待时间方面缩短13.2%;与基于两阶段框架模型的在线微任务分配改进(TGOA-Greedy)算法相比,在分配总效用方面提升13.9%。实验结果表明,该算法能够在提升任务分配总效用的同时缩短任务的平均等待时间,实现分配总效用与任务等待时间两者间的均衡。  相似文献   

3.
多Agent层次任务分配方法   总被引:2,自引:0,他引:2  
提出了一种层次任务分配方法,用于解决动态环境中的任务分配问题.利用全局分配方法为Agent分配合适的任务,当环境发生变换时,通过局部调整来解决任务和Agent之间的匹配问题,使得每个Agent能够根据局部信息选择理想的任务来执行,提高了分配算法的鲁棒性和多Agent整体效用.仿真实验结果表明,该方法是可行且有效的,能够解决动态环境中的任务分配问题.  相似文献   

4.
感知任务的合理分配是影响无人机目标区域覆盖的重要因素,针对任务需求差异并考虑无人机局部观测性和环境不确定性,提出一种面向目标区域协同覆盖的感知任务分配方法.将目标区域进行差异划分,构建基于分布式马尔可夫覆盖模型的任务分配控制框架;利用目标线路集和任务扩散调度序列集对目标区域进行差异化计算,并提出基于强化学习的任务差异化分配方法,实现动态目标区域的最优覆盖策略.仿真实验结果表明:在满足航向速率和空速的条件下,任意两台无人机之间可以合理地扩散调度任务,同时通过差异化学习方法使覆盖线路代价和目标函数适应值收敛稳定且覆盖率达到90%以上,实现对任务分配的有效控制.  相似文献   

5.
传感器网络能源有效任务分配算法   总被引:3,自引:0,他引:3  
为了延长网络生命期,传感器网络在设计过程中,通常利用节点本身的处理能力,进行网内处理,以减少通信量,节省能量.在传感器网络内引入处理或计算后,应用可以描述为一个任务集及任务之间的数据依赖关系.不同的任务分配方案导致应用执行所需的通信量和计算量不同,从而影响应用执行的能量消耗.在使用任务图对传感器网络应用描述的基础上,提出了传感器网络任务分配模型.由于应用的任务可划分为感知任务集和处理任务集,因而传感器网络中的任务分配可分成感知任务分配和处理任务分配两个阶段.针对处理任务分配,将其建模为二次0-1规划问题,并提出了分布式逐层优化分配算法OALL.仿真实验验证了分布式算法OALL的有效性.  相似文献   

6.
基于改进PSO算法的机动通信保障任务分配方法   总被引:1,自引:0,他引:1  
滑楠  赵延龙  于振华 《控制与决策》2018,33(9):1575-1583
针对机动通信保障问题建立任务分配模型,结合梯度下降法提出一种基于改进粒子群算法(TSPSO)的任务分配模型求解方法.在TSPSO算法中增加判断极值陷阱、粒子二次搜索、设定禁忌区域、粒子淘汰与生成4个部分,并将TSPSO算法与其他4种改进PSO算法应用于四种典型测试函数的优化.结果表明,TSPSO算法收敛精度更高、收敛速度更快.在基于TSPSO算法的任务分配模型求解方法中,基于各机动通信保障单元到不同通信地点分配概率的思想对粒子群进行编码和解码,提高模型求解效率.仿真结果表明,TSPSO算法能够快速寻找到机动通信保障任务最优分配方案.  相似文献   

7.
针对动态环境中的任务和Agent的动态变化问题,提出一种基于能力及任务需求的层次任务分配方法.利用全局分配方法为Agent分配合适的任务,当环境发生变换时,通过局部调整来解决任务和Agent之间的不适应问题,每个Agent能够根据局部信息选择理想的任务执行,提高了分配算法的鲁棒性.仿真实验表明该方法是可行及有效的,能够解决动态环境中的任务分配问题.  相似文献   

8.
如何以提高系统吞吐率为目标,高效地实现报文处理任务集在NP处理引擎组上的映射与分配,是基于NP的网络应用系统设计的关键问题之一。在NP应用初期,任务分配主要以人工方式完成,易出错且开发效率低。经过深入分析,认识到NP任务分配问题具有多极值搜索特性,进而提出一种基于改进遗传算法的自动分配方法。实验证明该方法能较快得到接近最优的分配结果,可有效提高此类系统的开发效率。  相似文献   

9.
作战任务的分解与分配是指挥决策中的重要过程,随着战场环境复杂度的增加,确定环境下的任务分配方法已不能适应作战需求。针对不确定性任务分配问题,分析作战任务分解、分配和执行过程中的多种不确定性因素,给出相应的形式化描述。在此基础上,提出一种基于概率推理的适应度计算方法,具体分析各种不确定性任务成功执行概率的计算过程,并给出算例进行验证。仿真结果表明,该方法能有效解决任务分配问题,并对任务分配方案进行定量评价。  相似文献   

10.
在多智体社会网络中,传统的任务分配模型一般采用直接面向任务执行者的分配机制.它们不考虑社会网络组织结构对任务分配性能的巨大影响,也很少透彻地研究不可靠社会中的任务分配.针对这些问题,本文开创性地研究了软硬件合一系统的任务分配,即按递阶、分层的思想设计了协作组织模型,并基于此提出了面向社区基于社会协调“软件人”的任务分配模型.模型研究过程中,提出了基于直接信任度和社区声誉的社区信任度评估机制、基于社区信任度和社区物理能力的节点选择机制、基于负载均衡的社区内任务分配机制和基于上下文资源的任务再分配策略.实验结果表明:与常见的直接面向任务执行者和基于资源的任务分配模型相比,所提出的模型具有更优的任务分配性能,且对社会任务环境变化具有更好的鲁棒性;社区内基于负载均衡的分配机制和基于上下文资源的再分配策略也有效提高了分配性能,降低了网络中的通信密度.  相似文献   

11.
The current trends in the robotics field have led to the development of large-scale multiple robot systems, and they are deployed for complex missions. The robots in the system can communicate and interact with each other for resource sharing and task processing. Many of such systems fail despite the availability of necessary resources. The major reason for this is their poor coordination mechanism. Task planning, which involves task decomposition and task allocation, is paramount in the design of coordination and cooperation strategies of multiple robot systems. Task allocation mechanism allocates the task in a mission to the robots by maximizing the overall expected performance, and thereby reducing the total allocation cost for the team. In this paper, we formulate a heuristic search-based task allocation algorithm for the task processing in heterogeneous multiple robot system, by maximizing the efficiency in terms of both communication and processing cost. We assume a set of decomposed tasks of a mission, which needs to be allocated to the robots. The near-optimal allocation schemes are found using the proposed peer structure algorithm for the given problem, where the number of the tasks is more than the robots present in the system. The cost function is the summation of static overhead cost of robots, assignment cost, and the communication cost between the dependent tasks, if they are assigned to different robots. Experiments are performed to verify the effectiveness of the algorithm by comparing it with the existing methods in terms of computational time and quality of solution. The experimental results show that the proposed algorithm performs the best under different problem scales. This proves that the algorithm can be scaled for larger system and it can work for dynamic multiple robot system.  相似文献   

12.
We present empirical results of an auction-based algorithm for dynamic allocation of tasks to robots. The results have been obtained both in simulation and using real robots. A distinctive feature of our algorithm is its robustness to uncertainties and to robot malfunctions that happen during task execution, when unexpected obstacles, loss of communication, and other delays may prevent a robot from completing its allocated tasks. Therefore tasks not yet achieved are resubmitted for bids every time a task has been completed. This provides an opportunity to improve the allocation of the remaining tasks, enabling the robots to recover from failures and reducing the overall time for task completion.  相似文献   

13.
In this paper, a processor allocation mechanism for NoC-based chip multiprocessors is presented. Processor allocation is a well-known problem in parallel computer systems and aims to allocate the processing nodes of a multiprocessor to different tasks of an input application at run time. The proposed mechanism targets optimizing the on-chip communication power/latency and relies on two procedures: processor allocation and task migration. Allocation is done by a fast heuristic algorithm to allocate the free processors to the tasks of an incoming application when a new application begins execution. The task-migration algorithm is activated when some application completes execution and frees up the allocated resources. Task migration uses the recently deallocated processors and tries to rearrange the current tasks in order to find a better mapping for them. The proposed method can also capture the dynamic traffic pattern of the network and perform task migration based on the current communication demands of the tasks. Consequently, task migration adapts the task mapping to the current network status. We adopt a non-contiguous processor allocation strategy in which the tasks of the input application are allowed to be mapped onto disjoint regions (groups of processors) of the network. We then use virtual point-to-point circuits, a state-of-the-art fast on-chip connection designed for network-on-chips, to virtually connect the disjoint regions and make the communication latency/power closer to the values offered by contiguous allocation schemes. The experimental results show considerable improvement over existing allocation mechanisms.  相似文献   

14.
This paper investigates the problem of allocating parallel application tasks to processors in heterogeneous distributed computing systems with the goal of maximizing the system reliability. The problem of finding an optimal task allocation for more than three processors is known to be NP-hard in the strong sense. To deal with this challenging problem, we propose a simple and effective iterative greedy algorithm to find the best possible solution within a reasonable amount of computation time. The algorithm first uses a constructive heuristic to obtain an initial assignment and iteratively improves it in a greedy way. We study the performance of the proposed algorithm over a wide range of parameters including problem size, the ratio of average communication time to average computation time, and task interaction density. The viability and effectiveness of our algorithm is demonstrated by comparing it with recently proposed task allocation algorithms for maximizing system reliability available in the literature.  相似文献   

15.
徐力  史少波 《计算机工程》2014,(1):83-87,97
针对软件无线电(SDR)应用同步数据流的特点,提出一种非对称多核SDR的任务调度和分配算法。该算法综合考虑任务之间的通信时间和任务固定流水,保证任务调度和分配的通用性和并行性。利用整数线性规划(ILP)方法对任务调度和分配进行建模,采用任务拆分方法优化调度和分配的结果,进一步提高任务调度和分配的执行效率。在目标SDR平台上实现IEEE 802.11a频偏估计处理的任务调度和分配,实验结果表明,该算法能提高5.97%的软件无线电平台吞吐量和3.03%的处理器核平均利用率,并减少34.31%的处理器核最长空闲等待时间。  相似文献   

16.
Presents an optimal solution to the problem of allocating communicating periodic tasks to heterogeneous processing nodes (PNs) in a distributed real-time system. The solution is optimal in the sense of minimizing the maximum normalized task response time, called the system hazard, subject to the precedence constraints resulting from intercommunication among the tasks to be allocated. Minimization of the system hazard ensures that the solution algorithm allocates tasks so as to meet all task deadlines under an optimal schedule, whenever such an allocation exists. The task system is modeled with a task graph (TG), in which computation and communication modules, communication delays and intertask precedence constraints are clearly described. Tasks described by this TG are assigned to PNs by using a branch-and-bound (B&B) search algorithm. The algorithm traverses a search tree whose leaves correspond to potential solutions to the task allocation problem. We use a bounding method that prunes, in polynomial time, nonleaf vertices that cannot lead to an optimal solution, while ensuring that the search path leading to an optimal solution will never be pruned. For each generated leaf vertex, we compute the exact cost using the algorithm developed by Peng and Shin (1993). The lowest-cost leaf vertex (one with the least system hazard) represents an optimal task allocation. Computational experiences and examples are provided to demonstrate the concept, utility and power of the proposed approach  相似文献   

17.
树型网格计算环境下的独立任务调度   总被引:17,自引:1,他引:17  
任务调度是实现高性能网格计算的一个基本问题,然而,设计和实现高效的调度算法是非常具有挑战性的.讨论了在网格资源计算能力和网络通信速度异构的树型计算网格环境下,独立任务的调度问题.与实现最小化任务总的执行时间不同(该问题已被证明是NP难题),为该任务调度问题建立了整数线性规划模型,并从该线性规划模型中得到最优任务分配方案??各计算节点最优任务分配数.然后,基于最优任务分配方案,构造了两种动态的需求驱动的任务分配启发式算法:OPCHATA(optimization-based priority-computation heuristic algorithm for task allocation)和OPBHATA(optimization-basedpriority-bandwidth heuristic algorithm for task allocation).实验结果表明:在异构的树型计算网格环境下实现大量独立任务调度时,该算法的性能明显优于其他算法.  相似文献   

18.
针对无线传感器网络的任务如何在最短时间内完成且充分利用网络资源的问题,提出了一种基于可分负载理论的无线传感器网络任务调度算法(WDTA).该算法根据网络中各个节点的处理能力和节点间的通信能力,将总任务从SINK节点下发至网络中.通过去除节点间的通信干扰来提高资源利用率和减少总任务完成时间.算法在两种分群结构的异构网络环境下进行了分析,得到了在各个节点上最合理的任务分配方案,以及最短的任务完成所需时间.理论分析了基于可分负载理论的无线传感器网络任务调度的极限情况.实验结果表明WDTA算法能够通过合理分配任务,而减少任务完成时间及节点能耗.该方案可以作为设计大规模无线传感器网络的原则.  相似文献   

19.
一种基于QoS的自适应网格失效检测器   总被引:2,自引:0,他引:2  
董剑  左德承  刘宏伟  杨孝宗 《软件学报》2006,17(11):2362-2372
失效检测器是构建可靠的网格计算环境所必需的基础组件之一.由于网格中存在大量对失效检测有着不同QoS需求的分布式应用,对于一个网格失效检测器来说,为保持其有效性和可扩展性,应该既能够准确提供应用程序所需的失效检测QoS,又能够避免为满足不同QoS而设计多套失效检测器所产生的多余负载.基于QoS基本评价指标,采用PULL模式主动检测策略实现了一种新的失效检测器--GA-FD(adaptive failure detector for grid),可以同时支持多个应用程序定量描述的QoS需求,不需要关于消息行为和时钟同步的任何假设.同时,证明了GA-FD在部分同步模型下可实现一个◇P类的失效检测器,并给出了相应的实验及数据.  相似文献   

20.
The problem of distributing tasks to processors in a distributed computing system is addressed. A task should be assigned to a processor whose capabilities are most appropriate for the execution of that task and excessive interprocessor communication is avoided. A simple algorithm for task allocation is presented. The execution costs and communication costs of the tasks are represented by arrays. A task is either assigned to a processor or fused with another task using a simple criterion. The execution and communication costs are then modified suitably. The process continues until all the tasks are assigned to processors. This algorithm also facilitates incorporation of various system constraints. It is applicable to random program structures and to a system containing any number of processors.  相似文献   

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