Hints to improve automatic load balancing with LeWI for hybrid applications

The DLB (Dynamic Load Balancing) library and LeWI (LEnd When Idle) algorithm provide a runtime solution to deal with the load imbalance of parallel applications independently of the source of imbalance. DLB relies on the usage of hybrid programming models and exploits the malleability of the second level of parallelism to redistribute computation power across processes.     

Distributed algorithms for QoS load balancing

We consider a dynamic load balancing scenario in which users allocate resources in a non-cooperative and selfish fashion. The perceived performance of a resource for a user decreases with the number of users that allocate the resource. In our dynamic, concurrent model, users may reallocate resources in a round-based fashion. As opposed to various settings analyzed in the literature, we assume that users have quality of service demands. A user has zero utility when falling short of a certain minimum performance threshold and having positive utility otherwise. Whereas various load-balancing protocols have been proposed for the setting without quality of service requirements, we consider protocols that satisfy an additional locality constraint: The behavior of a user depends merely on the state of the resource it currently allocates. This property is particularly useful in scenarios where the state of other resources is not readily accessible. For instance, if resources represent channels in a mobile network, then accessing channel information may require time-intensive measurements. We consider several variants of the model, where the quality of service demands may depend on the user, the resource, or both. For all cases we present protocols for which the dynamics converge to a state in which all users are satisfied. More importantly, the time to reach such a state scales nicely. It is only logarithmic in the number of users, which makes our protocols applicable in large-scale systems.     

LTE网络中具备QoS保障的动态负载均衡算法

研究了3GPPLTE网络中考虑不同服务质量(quality-of-service,QoS)要求的动态负载均衡算法.小区间的负载不均衡对于不同QoS要求用户有不同负面影响.对于有保障速率要求的用户,负载不均衡会导致较高的新呼叫阻塞率;而对于那些没有速率要求的用户,负载不均衡会导致繁忙小区中边缘用户过于恶化的吞吐量.全网中这两类用户的负载均衡问题紧密耦合,难以用一个统一的目标函数来分析研究.因此提出一个相应的多目标优化问题,其目标函数分别是针对全网内有QoS要求用户的负载均衡指示函数和针对全网内没有QoS要求用户的总效用函数,限制条件为实际小区物理资源和用户QoS要求.对该问题的复杂度进行了分析后,提出了一个实时的低复杂度低开销的分布式负载均衡算法结构,包括QoS保障的混合调度,QoS感知的负载均衡切换和呼叫准入控制.最后,系统级仿真结果显示提出的全新的负载均衡算法结构达到了较好的负载均衡效果,可以显著降低有QoS要求用户的新呼叫阻塞率,同时以略微损失全网无QoS要求用户总吞吐量的代价大幅提升繁忙小区中边缘用户的实际吞吐量.     

负载均衡算法在智慧矿山软件平台中的应用

针对现有负载均衡算法在处理智慧矿山系统数据时存在处理速度慢、无法合理利用现有资源完成任务调度等问题,提出一种基于布谷鸟搜索的加权最小连接数(CS-WLC)算法,并将其应用于智慧矿山软件平台解决负载均衡问题。该算法综合考虑后端服务器处理速率、内存容量、磁盘IO速率、网络吞吐量、进程数指标,通过对指标赋予权值计算各后端服务器利用率;根据计算结果,采用布谷鸟搜索算法对后端服务器进行全局寻优,得到一组较优解;考虑连接数及使用频率对后端服务器赋予权值,采用加权最小连接数(WLC)算法在较优解中选取负载较轻的后端服务器处理实时数据存取和用户访问请求。采用分布式融合性监控系统软件平台进行负载均衡测试,结果表明在数据量不断增多的情况下,与WLC算法相比,CS-WLC算法应答时延小、响应连接数多,从而验证了CS-WLC算法具有更好的负载均衡效果。     

A load index and load balancing algorithm for heterogeneous clusters

This paper presents a load balancing algorithm specifically designed for heterogeneous clusters, composed of nodes with different computational capabilities. The method is based on a new index, which takes into consideration two levels of processors heterogeneity: the number of cores per node and the computational power of each core. The experimental results show that this index allows achieving balanced workload distributions even on those clusters where heterogeneity can not be neglected.     

Advanced networking services for distributed multimedia streaming applications

Increased network speeds coupled with new services delivered via the Internet have increased the demand for intelligence and flexibility in network systems. This paper argues that both can be provided by new hardware platforms comprised of heterogeneous multi-core systems with specialized communication support. We present and evaluate an experimental network service platform that uses an emergent class of devices—network processors—as its communication support, coupled via a dedicated interconnect to a host processor acting as a computational core. A software infrastructure spanning both enables the dynamic creation of application-specific services on the network processor, mediated by middleware and controlled by kernel-level communication support. Experimental evaluations use a Pentium IV-based computational core coupled with an IXP 2400 network processor. The sample application services run on both include an image manipulation application and application-level multicasting.

一种动态的入侵检测系统负载均衡算法

目前的入侵检测不仅需要模式匹配,而且需要协议异常检测,提出了一种新动态的负载均衡算法,采用两层结构,对网络流量按照服务类型进行初步划分之后分别对每部分流量进行二次分配,并对每种类型的流量进行相应的协议异常检测。该算法能在不牺牲系统性能的前提下有效提高网络入侵检测系统的检测效率,降低误检率,并可有效地适应网络流量的变化,降低漏检率。     

A load balancing framework for adaptive and asynchronous applications

We describe the design of a flexible load balancing framework and runtime software system for supporting the development of adaptive applications on distributed-memory parallel computers. The runtime system supports a global namespace, transparent object migration, automatic message forwarding and routing, and automatic load balancing. These features can be used at the discretion of the application developer in order to simplify program development and to eliminate complex bookkeeping associated with mobile data objects. An evaluation of this system in the context of a three-dimensional tetrahedral advancing front parallel mesh generator shows that overall runtime improvements of 15 percent compared to common stop-and-repartition load balancing methods, 30 percent compared to explicit intrusive load balancing methods, and 42 percent compared to no load balancing are possible on large processor configurations. At the same time, the overheads attributable to the runtime system are a fraction of 1 percent of the total runtime. The parallel advancing front method is a coarse-grained and highly adaptive application and therefore exercises all of the features of the runtime system.     

Ant-based routing for wireless multimedia sensor networks using multiple QoS metrics

In wireless sensor networks, most routing protocols consider energy savings as the main objective and assume data traffic with unconstrained delivery requirements to be a given. However, the introduction of video and imaging sensors unveils additional challenges. The transmission of video and imaging data requires both energy efficiency and QoS assurance (end-to-end delay and packet loss requirements), in order to ensure the efficient use of sensor resources as well as the integrity of the information collected. This paper presents a QoS routing model for Wireless Multimedia Sensor Networks (WMSN). Moreover, based on the traditional ant-based algorithm, an ant-based multi-QoS routing metric (AntSensNet) is proposed. The AntSensNet protocol builds a hierarchical structure on the network before choosing suitable paths to meet various QoS requirements from different kinds of traffic, thus maximizing network utilization, while improving its performance. In addition, AntSensNet is able to use a efficient multi-path video packet scheduling in order to get minimum video distortion transmission. Finally, extensive simulations are conducted to assess the effectiveness of this novel solution and a detailed discussion regarding the effects of different system parameters is provided. Compared to typical routing algorithms in sensor networks and the traditional ant-based algorithm, this new algorithm has better convergence and provides significantly better QoS for multiple types of services in wireless multimedia sensor networks.     

无线多媒体传感器网络QoS路由算法研究

由于廉价的CMOS摄像头、麦克风的出现,以及对含有丰富信息的图像,视频和音频信息需求导致了无线多媒体传感器网络-(WMSN)的出现.WMSN具有资源有限、可变的信道容量、数据高度冗余等特点,使得WMSN的QoS路由具有极大的挑战性.提出了一种基于Mesh结构的WMSN,并在该结构体系下,提出了一种基于蚁群算法的QoS路由算法.实验研究表明,蚁群算法具有不依赖全局信息的优点,具有应用于WMSN的前景.实验同时表明,决定蚁群算法收敛速度以及会影响传感器网络性能的一些关键参数较难确定,需要进一步研究.     

A heuristic technique to improve energy efficiency with dynamic load balancing

The Journal of Supercomputing - Heterogeneous computers require a well-distributed workload to operate efficiently. When possible, this load balancing procedure should redistribute the workload...     

A self-routing load balancing algorithm in parallel computing: comparison to the central algorithm

Load balancing is an important stage of a system using parallel computing where the aim is the balance of workload among all processors of the system. In this paper, we introduce a new load balancing algorithm with new capabilities for parallel systems, among which is the independence of a separate route-finder algorithm between the load receiver and sender nodes. In addition to simulation of the new algorithm, due to similarity in behavior to the proposed algorithm, the central algorithm is simulated. Simulation results show that, the system performance increases with the increase of the degree of neighborhood between the processors. These results also indicate the algorithm’s high compatibility with environment changes.     

A topology-aware load balancing algorithm for clustered hierarchical multi-core machines

In this paper, we present a topology-aware load balancing algorithm for parallel multi-core machines and its proof of asymptotic convergence to an optimal solution. The algorithm, named HwTopoLB, aims to improve the application performance by reducing core idleness and communication delays. HwTopoLB was designed taking into account the properties of current parallel systems composed of multi-core compute nodes, namely their network interconnection, and their complex and hierarchical core topology. The latter comprises multiple levels of cache, and a memory subsystem with NUMA design. These systems provide high processing power at the expense of asymmetric communication costs, which can hamper the performance of parallel applications depending on their communication patterns if ignored. Our load balancing algorithm models asymmetries in terms of latencies and bandwidths, representing the distances and communication costs among hardware components. We have implemented HwTopoLB using the Charm++ Parallel Runtime System and evaluated its performance with two different benchmarks and one application. Our experimental results with HwTopoLB exhibit scalability over clustered multi-core compute nodes, and average performance improvements of 23% over execution without load balancers and 19% over the existing load balancing strategies on different multi-core systems.     

动态负载均衡算法在校园网格中的应用

校园网格能有效消除信息孤岛,实现我国高校的计算资源和信息资源的有效共享。一个亟待解决的问题是在校园网格环境下,服务器节点响应能力低下。目前已提出多种技术与方案以解决并提高校园网格的服务器节点的响应能力,负载均衡技术就是一种全新的技术。本文根据校园网格的特点和影响负载均衡的因素,对基于校园网格的负载均衡技术进行了分析和探讨,并提出一种动态负载均衡算法。     

A novel algorithm for routing and wavelength assignment considering the load balancing

For the problem of routing and wavelength assignment in Wavelength Division Multiplexing （WDM） optical transport network, an algorithm based on the state of links is proposed, which is named Tradeoff_LSDRAW, and which can select a path with the higher state level between a pair of nodes in a network. Finally, by an example network, we show that the algorithm has the stronger capability of selecting a better path between a pair of nodes, and can achieve the load balancing and reduce the congestion probability in WDM optical transport networks.     

An optimal migration algorithm for dynamic load balancing

The problem of redistributing the work load on parallel computers is considered. An optimal redistribution algorithm, which minimises the Euclidean norm of the migrating load, is derived. The relationship between this algorithm and some existing algorithms is discussed and the convergence of the new algorithm is studied. Finally, numerical results on randomly generated graphs as well as on graphs related to real meshes are given to demonstrate the effectiveness of the new algorithm. © 1998 John Wiley & Sons, Ltd.     

基于OpenFlow的数据中心网络负载均衡算法

现代数据中心网络(Date Center Network,DCN)经常会使用多路径(Multi Path,MP)拓扑结构,这样可以避免两节点间某条链路失效而导致的网络拥塞问题,而且增加了网络的带宽和容错率。传统的OSPF(Open Shortest Path First)路由算法会选择单条最短路径作为最终路径,这样可能会导致大部分数据流集中在单一路径上而出现网络拥塞,而其他可用路径处于闲置状态,不能充分地利用DCN中的链路资源,基于SDN(Software Defined Network)的集中化的调度方式能够提高网络利用效率。设计了一套基于Open Flow协议的链路负载均衡模型,详细阐述了它的总体框架和算法实现过程,并通过实验仿真验证了算法的可行性和有效性。     

An asynchronous and iterative load balancing algorithm for discrete load model

Diffusion algorithms are some of the most popular algorithms for dynamic load balancing in which loads move from heavily loaded processors to lightly loaded neighbor processors. To achieve a global load balance in a parallel computer, the algorithm is iterated until the load difference between any two processors is smaller than a specified value. Therefore, one fundamental property to be studied is algorithm convergence. Several analytical works on the convergence of different diffusion load balancing algorithms have been carried out, but they treat loads as non-negative real quantities. In this paper, we describe the Diffusion Algorithm Searching Unbalanced Domains (DASUD) algorithm, which uses loads as non-negative integer values and, unlike existing algorithms, reaches a local balance situation where the maximum load difference between any two processor in the set of neighbor processors for each processor is one load unit. The convergence property of an asynchronous implementation of DASUD using integer loads is proven theoretically.     

A practical approach to software metrics

Metrics programs that create meaningful change in software practice must start with business goals in mind. Software metrics are quantitative standards of measurement for various aspects of software projects. A well-designed metrics program will support decision making by management and enhance return on the IT investment. There are many aspects of software projects that can be measured, but not all aspects are worth measuring. Starting a new metrics program or improving a current program consists of five steps: identify business goals; select metrics; gather historical data; automate measurement procedures; and use metrics in decision making