Empirical prediction models for adaptive resource provisioning in the cloud

Cloud computing allows dynamic resource scaling for enterprise online transaction systems, one of the key characteristics that differentiates the cloud from the traditional computing paradigm. However, initializing a new virtual instance in a cloud is not instantaneous; cloud hosting platforms introduce several minutes delay in the hardware resource allocation. In this paper, we develop prediction-based resource measurement and provisioning strategies using Neural Network and Linear Regression to satisfy upcoming resource demands.Experimental results demonstrate that the proposed technique offers more adaptive resource management for applications hosted in the cloud environment, an important mechanism to achieve on-demand resource allocation in the cloud.     

Enhancing computer-supported writing of learning protocols by adaptive prompts

Cognitive and metacognitive prompts are a central support procedure in eHELp a computer-based environment that supports the writing of learning protocols. In order to investigate the effectiveness of adapting prompts, 79 students revised a learning protocol in eHELp either supported by prompts that were adapted on the basis of the results of an integrated learning-strategy questionnaire or a meta-knowledge test, respectively, by randomly selected prompts, or without any support. Adaptive prompts improved the quality of the learning protocols and fostered the acquisition of declarative knowledge and deep understanding, irrespective of the applied diagnostic instrument. In conclusion, open-ended learning tasks like the writing of learning protocols can be made more effective by adaptive support based on prior strategy assessment.     

A hybrid HPC/cloud distributed infrastructure: Coupling EC2 cloud resources with HPC clusters to run large tightly coupled multiscale applications

In this paper, we report on the experimental results of running a large, tightly coupled, distributed multiscale computation over a hybrid High Performance Computing (HPC) infrastructures. We connected EC2 based cloud clusters located in USA to university clusters located in Switzerland. We ran a concurrent multiscale MPI based application on this infrastructure and measured the overhead induced by extending our HPC clusters with EC2 resources. Our results indicate that accommodating some parts of the multiscale computation on cloud resources can lead to low performance without a proper adjustment of CPUs power and workload. However, by enforcing a load-balancing strategy one can benefit from the extra Cloud resources.     

云计算下的多源信息资源云体系及云服务模型研究

针对传统信息服务模式存在信息资源规模单一、虚拟化程度低、自适应程度较差及知识泛化等问题, 同时考虑到目前云服务体系中忽略多源信息资源这一重要因素, 提出了云计算环境下的多源信息资源云体系及服务模型。首先构建了基于云计算的多源信息资源云体系, 对信息资源搜索、查询及匹配等技术进行阐述, 进而提出了新的云服务模型——基于云计算的多源信息资源即服务（multi-source information resource as a service, MIRaaS）, 在此基础上搭建了该模型在商务领域下的应用平台。分析表明, 该模型能对多源信息资源进行重构、分析、整合及匹配, 并充分考虑用户体验, 很好地扩展了云服务的研究范围及应用领域。     

Deadline-driven provisioning of resources for scientific applications in hybrid clouds with Aneka

Scientific applications require large computing power, traditionally exceeding the amount that is available within the premises of a single institution. Therefore, clouds can be used to provide extra resources whenever required. For this vision to be achieved, however, requires both policies defining when and how cloud resources are allocated to applications and a platform implementing not only these policies but also the whole software stack supporting management of applications and resources. Aneka is a cloud application platform capable of provisioning resources obtained from a variety of sources, including private and public clouds, clusters, grids, and desktops grids. In this paper, we present Aneka’s deadline-driven provisioning mechanism, which is responsible for supporting quality of service (QoS)-aware execution of scientific applications in hybrid clouds composed of resources obtained from a variety of sources. Experimental results evaluating such a mechanism show that Aneka is able to efficiently allocate resources from different sources in order to reduce application execution times.     

通过链路失效预测机制提高AODV协议的性能

将链路预测机制引入AODV协议中,使节点利用接收分组的能量及时发现并删除缓存中的失效路由,并在此基础上利用跳数值进行了优化。仿真结果表明,改进后的AODV协议在高负载网络中明显降低了端到端分组平均时延,提高了网络中的报文投递率。     

Enhancing the performance of hybrid genetic algorithms by differential improvement

A differential improvement modification to Hybrid Genetic Algorithms is proposed. The general idea is to perform more extensive improvement algorithms on higher quality solutions. Our proposed Differential Improvement (DI) approach is of rather general character. It can be implemented in many different ways. The paradigm remains invariant and can be easily applied to a wider class of optimization problems. Moreover, the DI framework can also be used within other Hybrid metaheuristics like Hybrid Scatter Search algorithms, Particle Swarm Optimization, or Bee Colony Optimization techniques.     

Value of information based scheduling of cloud computing resources

Traditionally, heavy computational tasks were performed on a dedicated infrastructure requiring a heavy initial investment, such as a supercomputer or a data center. Grid computing relaxed the assumptions of the fixed infrastructure, allowing the sharing of remote computational resources. Cloud computing brought these ideas into the commercial realm and allows users to request on demand an essentially unlimited amount of computing power. However, in contrast to previous assumptions, this computing power is metered and billed on an hour-by-hour basis.In this paper, we are considering applications where the output quality increases with the deployed computational power, a large class including applications ranging from weather prediction to financial modeling. We are proposing a computation scheduling that considers both the financial cost of the computation and the predicted financial benefit of the output, that is, its value of information (VoI). We model the proposed approach for an example of analyzing real-estate investment opportunities in a competitive environment. We show that by using the VoI-based scheduling algorithm, we can outperform minimalistic computing approaches, large but fixedly allocated data centers and cloud computing approaches that do not consider the VoI.     

云计算下多源信息资源云服务模型可信保障机制的研究

针对云计算环境下多源信息资源云服务模型在复杂异构的云网络下存在安全、容错、监管等可信性问题,以及现存保障机制缺乏普适性和独立性,提出一种能从制度上保证服务监管的第三方可信保障机制.分析比对多种信息资源服务模式,将可信性机理、信誉评估、云端访问加密等技术融合,引入第三方信任平台,设计第三方监管角色,搭建独立于服务过程之外的第三方可信保障机制,并设立访问控制模型保障其自身可信性.通过构建商务领域下的应用示例平台,表明该保障机制能充分考虑云计算环境下多源信息资源服务体系中的共性问题,能面向不同应用领域,适用于各种不同类型信息服务应用,具有一定的普适性.     

Enabling cost-aware and adaptive elasticity of multi-tier cloud applications

Elasticity (on-demand scaling) of applications is one of the most important features of cloud computing. This elasticity is the ability to adaptively scale resources up and down in order to meet varying application demands. To date, most existing scaling techniques can maintain applications’ Quality of Service (QoS) but do not adequately address issues relating to minimizing the costs of using the service. In this paper, we propose an elastic scaling approach that makes use of cost-aware criteria to detect and analyse the bottlenecks within multi-tier cloud-based applications. We present an adaptive scaling algorithm that reduces the costs incurred by users of cloud infrastructure services, allowing them to scale their applications only at bottleneck tiers, and present the design of an intelligent platform that automates the scaling process. Our approach is generic for a wide class of multi-tier applications, and we demonstrate its effectiveness against other approaches by studying the behaviour of an example e-commerce application using a standard workload benchmark.     

Energy efficient utilization of resources in cloud computing systems

The energy consumption of under-utilized resources, particularly in a cloud environment, accounts for a substantial amount of the actual energy use. Inherently, a resource allocation strategy that takes into account resource utilization would lead to a better energy efficiency; this, in clouds, extends further with virtualization technologies in that tasks can be easily consolidated. Task consolidation is an effective method to increase resource utilization and in turn reduces energy consumption. Recent studies identified that server energy consumption scales linearly with (processor) resource utilization. This encouraging fact further highlights the significant contribution of task consolidation to the reduction in energy consumption. However, task consolidation can also lead to the freeing up of resources that can sit idling yet still drawing power. There have been some notable efforts to reduce idle power draw, typically by putting computer resources into some form of sleep/power-saving mode. In this paper, we present two energy-conscious task consolidation heuristics, which aim to maximize resource utilization and explicitly take into account both active and idle energy consumption. Our heuristics assign each task to the resource on which the energy consumption for executing the task is explicitly or implicitly minimized without the performance degradation of that task. Based on our experimental results, our heuristics demonstrate their promising energy-saving capability.     

A general framework to understand parallel performance in heterogeneous clusters: analysis of a new adaptive parallel genetic algorithm

This paper presents a general model to define, measure and predict the efficiency of applications running on heterogeneous parallel computer systems. Using this framework, it is possible to understand the influence that the heterogeneity of the hardware has on the efficiency of an algorithm. This methodology is used to compare an existing parallel genetic algorithm with a new adaptive parallel model. All the performance measurements were taken in a loosely coupled cluster of processors.     

面向云文件系统的隔离性度量方法研究

随着云计算的快速发展,云文件系统在云计算基础设施中扮演着越来越重要的角色。尽管目前业界已有不少面向云文件系统的性能评测工具,但大多数评测工具仅关注于传统的系统性能指标,比如IOPS和吞吐量,难以评估云文件系统在多租户环境下的性能隔离性。由于云环境I/O负载的动态性和异构性,所以准确评估云文件系统的隔离性变得更加具有挑战性。提出了一种新型的云文件系统隔离性度量模型,并在一个基准测试工具Porcupine中进行了实现。Porcupine通过模拟真实负载特征的I/O请求,实现对负载与性能的准确仿真并提高文件系统的测试效率。通过对Ceph文件系统的实验,验证了所提出的隔离性度量模型的有效性及准确性。     

Method of multiagent scheduling of resources in cloud computing environments

The paper describes a method of scheduling distributed computing resources in cloud environments for solving user tasks using a variety of software agents physically located on separate processor units connected to the cloud infrastructure and representing their interests in the process of computing. The advantages of the proposed approach are as follows: Firstly, the fast tracking of all resource changes occurring to the processing unit using agents and real time correction of the computing process taking into account these changes, which in turn makes it possible to use computing resources with a dynamically changing performance in the cloud environment (e.g., personal privately owned computers), and, secondly, a cost reduction for the cloud infrastructure because there is no need to introduce expensive dedicated nodes that perform service functions into its structure.     

CloudSim: a toolkit for modeling and simulation of cloud computing environments and evaluation of resource provisioning algorithms

Cloud computing is a recent advancement wherein IT infrastructure and applications are provided as ‘services’ to end‐users under a usage‐based payment model. It can leverage virtualized services even on the fly based on requirements (workload patterns and QoS) varying with time. The application services hosted under Cloud computing model have complex provisioning, composition, configuration, and deployment requirements. Evaluating the performance of Cloud provisioning policies, application workload models, and resources performance models in a repeatable manner under varying system and user configurations and requirements is difficult to achieve. To overcome this challenge, we propose CloudSim: an extensible simulation toolkit that enables modeling and simulation of Cloud computing systems and application provisioning environments. The CloudSim toolkit supports both system and behavior modeling of Cloud system components such as data centers, virtual machines (VMs) and resource provisioning policies. It implements generic application provisioning techniques that can be extended with ease and limited effort. Currently, it supports modeling and simulation of Cloud computing environments consisting of both single and inter‐networked clouds (federation of clouds). Moreover, it exposes custom interfaces for implementing policies and provisioning techniques for allocation of VMs under inter‐networked Cloud computing scenarios. Several researchers from organizations, such as HP Labs in U.S.A., are using CloudSim in their investigation on Cloud resource provisioning and energy‐efficient management of data center resources. The usefulness of CloudSim is demonstrated by a case study involving dynamic provisioning of application services in the hybrid federated clouds environment. The result of this case study proves that the federated Cloud computing model significantly improves the application QoS requirements under fluctuating resource and service demand patterns. Copyright © 2010 John Wiley & Sons, Ltd.     

基于复杂云资源查询的HChord索引机制

为了研究复杂云资源在巨大资源池中快速定位和查找问题,结合分布式对等技术资源定位的优势,提出分层的HChord云对等模型,通过提取云资源多维属性特征向量构建资源查询索引和相似资源聚类,建立全局与局部索引及缓存机制,并独到地提出依赖备份超级节点数来控制索引缓存率的方法.仿真实验表明,HChord模型比HTC-Chord模型在资源定位时需要更短的平均路径长度;验证HChord模型下不同索引缓存率对资源定位路径不同的有利影响.结果表明,分层HChord模型下构建的资源聚类和索引缓存机制,以牺牲少数节点维护开销能使资源在非常有效的路径范围内被定位.     

云计算环境下动态资源碎片管理机制

针对云计算环境下用户所需资源与服务资源规格不完全相符以及在资源预留过程中完整资源被切割而产生的资源碎片问题,提出一种云环境下考虑碎片资源重利用的动态资源管理策略。研究了云计算环境下资源碎片的形成原因,构建了碎片资源池,制定了任务对碎片资源接收的度量标准,在充分考虑当前任务对资源查找、调度、匹配的同时,进一步讨论了任务调度对资源的分割情况,进而指出资源碎片对后续任务接收能力的影响,搭建了云计算环境下动态资源碎片调度模型。理论分析和Cloudsim仿真实验证明,该资源管理策略能有效实现碎片资源的优化重组,提高了资源对后续任务的接收能力,与此同时保证了较高的资源利用率。