一种自适应的分布式调度策略

针对集群系统中集中调度存在的单一失效和性能瓶颈问题，本文提出了一种具有自适应特性的分布式集群网络服务器，采用一种新的自适应分布式调度策略，完成对客户请求的动态调度．该策略引入了一种与负载相关的竞争延迟机制，能够根据负载的变化自动选择服务节点，具有很好的自适应性，而且无需节点间通讯，调度的开销小，成本低．另外．该系统通过内核模块实现，做到对客户端和服务端程序透明，其管理配置也相当简单．测试数据表明，该策略具有较好的可扩展性和负载均衡性，实用性强．     

基于同构多核处理器的任务调度

随着现代应用对计算机性能要求的提高,计算机主频不断提升。由于功耗和半导体工艺的限制,仅靠提高单核主频难以继续维持“摩尔定律”,同构多核处理器（Homogeneous Multi-core）应运而生。在同构多核处理器的支持下,一个芯片汇集多个地位对等、结构相同的通用处理器核,以最小的代价满足了提高系统性能、负载均衡、处理器容错的需要。并行体系结构需要结合与之适应的软件实现性能效益的倍增。本文从操作系统层面,针对处理器结构的变化,研究并实现多核任务调度。系统采用混合调度策略,簇间独立调度,簇内统一调度。从调度模式、调度算法、分配算法、调度时机等方面详细分析了多核调度的原理和实现机制。最后通过模拟实验证明功能正确性及算法可调度性。     

Comparison of OpenMP 3.0 and Other Task Parallel Frameworks on Unbalanced Task Graphs

The UTS benchmark is used to evaluate the expression and performance of task parallelism in OpenMP 3.0 as implemented in a number of recently released compilers and run-time systems. UTS performs parallel search of an irregular and unpredictable search space, as arises, e.g., in combinatorial optimization problems. As such UTS presents a highly unbalanced task graph that challenges scheduling, load balancing, termination detection, and task coarsening strategies. Expressiveness and scalability are compared for OpenMP 3.0, Cilk, Cilk++, Intel Thread Building Blocks, as well as an OpenMP implementation of the benchmark without tasks that performs all scheduling, load balancing, and termination detection explicitly. Current OpenMP 3.0 run time implementations generally exhibit poor behavior on the UTS benchmark. We identify inadequate load balancing strategies and overhead costs as primary factors contributing to poor performance and scalability.     

基于随机模型的云平台资源调度策略设计

针对云计算资源管理的实际需求,提出一种基于随机模型的云平台调度策略,设计合理高效的资源调度算法,解决传统代数模型请求丢失率高以及其他随机模型负载均衡指标性能较差的问题,从而在服务性能和执行效率的基础上保证服务器的资源负载,使云平台处于相对稳定的状态。在实验环境中的验证结果表明,该调度策略能够优化虚拟资源的使用效率和服务响应时间,同时能够达到较好的负载均衡并降低运营成本。     

基于移动Agent的分布式测控系统任务调度研究

动态任务调度是分布式测控系统中的一项关键技术。基于移动Agent提出了一种新的分布式测控系统动态任务调度算法。算法采用IBM Aglets系统设计和执行移动Agent,利用移动Agent-Aglet在系统运行过程中动态迁移任务,从而有效地提高了系统效率,实现了负载均衡的目标。详细介绍了任务迁移的实现及Aglet通信机制。     

Application‐specific thread schedulers for distributed applications

This paper describes our work to improve the performance of distributed applications. We aim at certain application characteristics such as balancing load, allowing separately written applications to work better together, allowing a distributed application to adapt its behavior in more flexible ways, and so on. Our approach is to write application‐specific schedulers, which can access the global state of the application in making scheduling decisions. To achieve this goal, we extended our earlier work on CATAPULTS ( C reating A nd T esting AP plication‐specific U ser L evel T hread S chedulers), a domain‐specific language for creating and testing application‐specific user‐level thread schedulers, to distributed applications by adding ‘master schedulers’ for dealing with the distributed parts of applications. This paper presents our design of, experimentation with, and implementation of distributed CATAPULTS. This paper presents several realistic examples to measure the feasibility of this approach, specifically: a website application, an embedded application, and load balancing. Each example has a scheduling goal for which we developed a customized scheduler. We measured the performance with and without the customized scheduler. The customized scheduler for each example was fairly straightforward to develop and each achieved its scheduling goal. Copyright © 2011 John Wiley & Sons, Ltd.     

一种基于cookie会话保持的LVS集群系统

针对基于源IP会话保持的IPVS在高速代理上网环境中存在的会话失效和负载不均衡问题,研究了LVS系统的设计原理与实现方法,并结合Web应用中cookie会话保持机制,提出了基于cookie会话保持的改进方案。实验结果表明,改进的基于cookie会话保持的IPVS负载均衡集群系统能有效地解决高速代理上网环境中存在的会话失效和负载不均衡的问题,同时在相同的并发用户量的情况下响应时间更短、吞吐率更高,特别是在高并发情况下集群性能更优。     

基于退火策略的分布式资源负载均衡算法

针对分布式资源导致的访问热点等一系列问题,建立了一个用于分布式资源退火的处理模型.根据该模型,提出了基于退火策略的分布式资源负载均衡算法;该算法通过访问分类、定向扩散等方法提高了系统性能.性能及试验分析表明,该算法能够减少系统内部通信量,抑制资源扩散的抖动现象等.     

异构分布式环境下DNS动态负载均衡模型研究

DNS负载均衡是服务器群集负载均衡策略的典型应用方案之一。分析了目前DNS负载均衡的现状和异构分布式系统的特征,提出一种自适应生存期的动态调度负载均衡模型,并且描述了该模型的实现策略。     

一种用于PC存储集群的动态负载平衡策略

在大规模并行分布处理系统中,各节点间的负载平衡调度是最常见的关键性问题之一。该文首先简单介绍了负载平衡的目标和基本的集群任务调度算法,然后针对一种PC存储集群提出了一个分布式任务调度和动态负载平衡策略,对该策略进行了详细的介绍,并对其进行了性能分析。     

分层负载平衡调度系统的设计与实现

随着分布式系统的广泛应用,提高系统性能的负载平衡策略也日益为人们所重视。文章在分析负载平衡调度问题现有研究成果、提出基于规则的分层负载平衡调度模型[10]的基础之上,设计、实现了一个分层负载平衡调度系统。实验结果表明,与传统的动态调度与静态调度相比,分层负载平衡调度系统具有较好的问题求解效率和适用性。     

分布式文件系统中的负载平衡技术

I／O，特别是存储系统成为了计算机系统结构的核心，因而用于组织存储内容并提供使用接口的文件系统中的负载平衡研究也成为提高整个系统性能和可扩展性的重要组成部分。在分析现有文件系统负载平衡技术的优缺点的基础上，提出了一种动态的负载平衡技术，并给出此技术的实现方案和可行性分析。     

基于交易服务的一个动态负载平衡模型

CORBA是当前被广泛采用的分布式对象平台,它成功地解决了异种平台的互操作问题。为了提高整个基于CORBA的分布式系统的性能,负载平衡成为CORBA应当考虑的问题。本文给出了一个基于交易服务的通用动态负载平衡模型。它不仅实现了CORBA负载平衡,而且其对交易服务的扩展对用户透明,原有应用可以直接与之集成。文章最后给出了模型的性能的评价和分析。     

带输入队列并行交换的负载平衡分析

并行交换是新兴的交换技术,基于该技术能够利用小型交换模块来构建大容量的交换系统,例如太比特或更高容量的交换机.把带输入队列的并行交换称为带缓存并行交换(buffered parallel switch,简称BPS),重点研究其中并行且独立工作的交换模块之间的负载平衡问题.从不同角度出发,提出两种负载平衡的定义.基于两种定义,分别分析了BPS负载平衡的条件并提出分布式调度算法族.最后,提出一种简单而有效的调度算法,该算法能在无加速比BPS中同时满足两种定义,仿真实验结果表明了该算法的有效性和良好性能.另外,就算法的工程实现进行了讨论.     

Agent scheduling model for adaptive dynamic load balancing in agent-based distributed simulations

Agent-based distributed simulations are confronted with load imbalance problem, which significantly affects simulation performance. Dynamic load balancing can be effective in decreasing simulation execution time and improving simulation performance. The characteristics of multi-agent systems and time synchronization mechanisms make the traditional dynamic load balancing approaches not suitable for dynamic load balancing in agent-based distributed simulations. In this paper, an adaptive dynamic load balancing model in agent-based distributed simulations is proposed. Due to the complexity and huge time consuming for solving the model, a distributed approximate optimized scheduling algorithm with partial information (DAOSAPI) is proposed. It integrates the distributed mode, approximate optimization and agent set scheduling approach. Finally, experiments are conducted to verify the efficiency of the proposed algorithm and the simulation performance under dynamic agent scheduling. The experiments indicate that DAOSPI has the advantage of short execution time in large-scale agent scheduling, and the distributed simulation performance under this dynamic agent scheduling outperforms that under static random agent distribution.     

A Distributed Drafting Algorithm for Load Balancing

It is desirable for the load in a distributed system to be balanced evenly. A dynamic process migration protocol is needed in order to achieve load balancing in a user transparent manner. A distributed algorthim for load balancing which is network topology independent is proposed in this paper. Different network topologies and low-level communications protocols affect the choice of only some system design parameters. The "drafting" algorithm attempts to compromise two contradictory goals: maximize the processor utilization and minimize the communication overhead. The main objective of this paper is to describe the dynamic process migration protocol based on the proposed drafting algorithm. A sample distributed system is used to further illustrate the drafting algorithm and to show how to define system design parameters. The system performance is measured by simulation experiments based on the sample system.     

面向云环境的Flink负载均衡策略

作为新一代的大数据计算引擎,Flink得到了广泛应用。Flink在云环境下进行容器化部署时,其默认任务调度算法不能感知节点的资源信息,导致即时调整负载和自主均衡能力较差,而主流的容器编排工具虽然提供了管理容器的可能性,却也未能结合Flink特点解决平衡资源利用的同时降低容器组内的通信开销问题。针对以上问题开展研究,提出了一种面向云环境的Flink负载均衡策略FLBS,综合考虑了Flink集群中算子的分布特点和容器间通信机制,以节点间通信开销和均衡负载作为评估标准。实验结果表明,与Flink默认调度策略相比,FLBS能够有效提高计算效率,提升系统性能。     

Engineering and analysis of fixed priority schedulers

Scheduling theory holds great promise as a means to a priori validate timing correctness of real-time applications. However, there currently exists a wide gap between scheduling theory and its implementation in operating system kernels running on specific hardware platforms. The implementation of any particular scheduling algorithm introduces overhead and blocking components which must be accounted for in the timing correctness validation process. This paper presents a methodology for incorporating the costs of scheduler implementation within the context of fixed priority scheduling algorithms. Both event-driven and timer-driven scheduling implementations are analyzed. We show that for the timer-driven scheduling implementations the selection of the timer interrupt rate can dramatically affect the schedulability of a task set, and we present a method for determining the optimal timer rate. We analyzed both randomly generated and two well-defined task sets and found that their schedulability can be significantly degraded by the implementation costs. Task sets that have ideal breakdown utilization over 90% may not even be schedulable when the implementation costs are considered. This work provides a first step toward bridging the gap between real-time scheduling theory and implementation realities. This gap must be bridged for any meaningful validation of timing correctness properties of real-time applications     

IMPROVED RESOURCE UTILIZATION WITH BUFFERED COSCHEDULING

We present buffered coscheduling, a new methodology to multitask parallel jobs in a message-passing environment and to develop parallel programs that can pave the way to the efficient implementation of a distributed operating system. Buffered coscheduling is based on three innovative techniques: communication buffering, strobing, and non-blocking communication. By leveraging these techniques, we can perform effective optimizations based on the global status of the parallel machine rather than on the limited knowledge available locally to each processor

The advantages of buffered coscheduling include higher resource utilization, reduced communication overhead, efficient implementation of flow-control strategies and fault-tolerant protocols, accurate performance modeling, and a simplified yet ;.till expressive parallel programming model which offloads many resource-management tasks to the operating system. Preliminary experimental results show that buffered coscheduling is very effective in increasing the overall performance in the presence of load imbalance and communication-intensive workloads and is relatively insensitive to the local process scheduling strategy.     

基于覆盖网络的海上信息栅格无线传输系统研究

文章在通信资源的形式化描述基础上,设计了一种信息栅格的传输体系,为一体化信息系统提供透明的传输服务。针对多重网络传输服务与网络性能的多样性,提出了一种基于作战任务的层次覆盖网络模型,以及实现网络负载均衡的QoS路由算法。