Research on Protocol Migration

This paper elaborates the concept and model of protocol migration in network interconnection.Migration strategies and principles are discussed and several cases are studied in detail which show the basic procedure and techniques used in protocol migration.     

虚拟机动态迁移方法

对虚拟机动态迁移方法的研究背景、研究意义以及研究现状进行综述,分别介绍了内存预拷贝迁移、内存后拷贝迁移、内存混合复制迁移和基于日志跟踪重现的迁移方法,对其算法思想、关键技术、实现机制以及性能等进行概括、分析和比较,并针对当前主流的预拷贝迁移的优化策略予以分类阐述。最后,对动态迁移方法有待深入的研究热点和发展趋势进行展望。     

Computer simulation of barrier-island migration

Five depositional subenvironments are commonly recognized in barrier island complexes: lower shoreface, middle shoreface, beach-upper shoreface, eolian, and lagoon. Facies belonging to these subenvironments can be characterized in terms of primary structures and sediment attributes. The facies assemblages which occur in the geologic record differ according to strandline still-stand, transgression, or regression and rates of basin subsidence. A FORTRAN program was developed to produce graphic output to aid in understanding facies relationships produced by these controlling parameters.     

A data decomposition method for stepwise migration of complex legacy data

Sooner or later, in almost every company, the maintenance and further development of large enterprise information technology (IT) applications reaches its limit. From the point of view of cost as well as technical capability, legacy applications must eventually be replaced by new enterprise IT applications. Data migration is an inevitable part of making this switch. While different data migration strategies can be applied, incremental data migration is one of the most popular strategies, due to its low level of risk: the entire data volume is split into several data tranches, which are then migrated in individual migration steps. The key to a successful migration is the strategy for decomposing the data into suitable tranches. This paper presents a method for data decomposition where the entire data volume of a monolithic enterprise IT application is split into independent data migration tranches. Each tranche comprises the data to be migrated in one migration step, which is usually executed during the application's downtime window. Unlike other methods, which describe data migration in a highly abstract way, we propose specific heuristics for data decomposition into independent data packages (tranches). The data migration approach described here is being applied in one of the largest migration projects currently underway in the European health care sector, comprising millions of customer records.     

面向多租户的关键虚拟机动态迁移方法研究

提出一种面向多租户的关键虚拟机动态迁移方法。首先,根据租户对虚拟机的安全需求设定关键虚拟机的比例,减少虚拟机动态迁移的数量;然后,通过虚拟机之间共存时间约束条件最大化降低虚拟机动态迁移的频率;最后,以最小化迁移开销作为虚拟机迁移的目标函数,进一步降低虚拟机迁移带来的开销。实验表明,与现有的防御方法相比,该方法在有效防御侧信道攻击的前提下,能够减少对网络服务性能的影响,降低虚拟机迁移的成本,更加适用于大规模的网络场景。     

Transparent partial page migration between CPU and GPU

Despite the increasing investment in integrated GPU and next-generation interconnect research,discrete GPU connected by PCIe still account for the dominant position of the market,the management of data communication between CPU and GPU continues to evolve.Initially,the programmer explicitly controls the data transfer between CPU and GPU.To simplify programming and enable systemwide atomic memory operations,GPU vendors have developed a programming model that provides a single,virtual address space for accessing all CPU and GPU memories in the system.The page migration engine in this model automatically migrates pages between CPU and GPU on demand.To meet the needs of high-performance workloads,the page size tends to be larger.Limited by low bandwidth and high latency interconnects compared to GDDR,larger page migration has longer delay,which may reduce the overlap of computation and transmission,waste time to migrate unrequested data,block subsequent requests,and cause serious performance decline.In this paper,we propose partial page migration that only migrates the requested part of a page to reduce the migration unit,shorten the migration latency,and avoid the performance degradation of the full page migration when the page becomes larger.We show that partial page migration is possible to largely hide the performance overheads of full page migration.Compared with programmer controlled data transmission,when the page size is 2MB and the PCIe bandwidth is 16GB/sec,full page migration is 72.72×slower,while our partial page migration achieves 1.29×speedup.When the PCIe bandwidth is changed to 96GB/sec,full page migration is 18.85×slower,while our partial page migration provides 1.37×speedup.Additionally,we examine the performance impact that PCIe bandwidth and migration unit size have on execution time,enabling designers to make informed decisions.     

软件移植理论与技术研究

从软件可移植性研究和软件移植方法两方面出发,分别探讨了可移植性定义、可移植性度量、可移植性软件工程、源代码移植方法、二进制移植方法的研究现状,最后指出了软件移植的发展趋势。     

基于模糊满意度的软件定义网络交换机迁移策略

针对软件定义网络中多控制器间负载均衡的迁移代价和迁移效率问题,提出一种基于模糊满意度的交换机迁移策略。首先,构建均衡判断矩阵,监测控制器负载状态,且提出交换机组选择度,划分交换机组以选取迁移交换机;其次,考虑迁移代价和负载均衡率,构建模糊满意度迁移竞争模型,且提出改进蚁群算法优化求解,选择最佳迁入控制器;最后,将迁移交换机迁往迁入控制器,实现交换机的快速迁移。实验结果表明,与现有交换机迁移策略相比,所提方法在保证较高负载均衡率的同时,进一步优化了网络性能,迁移代价平均减少约26.8%,控制器平均响应时间缩短约0.41 s,改善了交换机迁移过程。     

An adaptive plan-oriented and continuous software migration to cloud in dynamic enterprises

Replacing existing software/hardware components with their equivalent cloud services is an important decision faced by IT managers in today's enterprises. A variety of possible migration targets and cloud services with too many configurations and cost models, disparate and changing strategic objectives of the enterprise management that triggers the migration process, and the complex structure of the legacy applications make software migration to the cloud a challenging issue. In contrast to the existing approaches that model the migration process as an optimization problem to find the optimal deployment of software components on cloud services without presenting a practical migration plan, in this paper, a plan-oriented migration approach is proposed by which the enterprise management is able to follow migration steps of a valid plan. All valid plans are modeled using a labeled transition system, and a recommender engine directs the management through the possible migration paths using predefined fitness functions. It was observed that, particularly in dynamic and changing conditions that a flexible migration plan is essential, the proposed plan-oriented method is very much effective in satisfying the enterprise strategic objectives. Evaluations have been performed using two quality indicators: total cost of ownership and scalability index.     

一种基于组通信机制的安全主动漂移技术

主动漂移机制是在系统受到入侵攻击或故障时采取“走为上”的策略,并让服务在服务器池间作漂移运动,从而提高了服务的生存能力。分析了现有的主动漂移机制存在的安全性问题,并有针对性地引入了安全的组通信机制,从而提出了一种在离散对数难题和DDH假设下安全的主动漂移模型,最后对其进行了安全性分析。     

一种改进人口迁移算法在蛋白质折叠模拟中的应用

PMA（Population Migration Algorithm）算法已在蛋白质非晶格模型中做了模拟测试,结果表明具有较强的全局搜索能力和稳定性。针对PMA算法的思想,提出了对算法的一种改进。使用该改进算法求解蛋白质折叠构形预测的二维非晶格模型取得了较好的计算结果。     

面向服务的未来互联网服务迁移机制

研究了基于传统互联网架构、覆盖网技术的现有服务迁移技术,解决了网络拥塞问题.现有服务迁移技术存在网络不可达、额外交互流量大和服务响应效率低的不足,结合网络用户行为和服务类别的特点,提出了基于服务计算的未来互联网体系结构的服务迁移触发策略,以及静、动态服务迁移算法,并在搭建的原型系统上对算法进行了测试.测试结果表明,这两种算法在降低骨干网服务请求流量的同时,能够明显提高服务迁移效率.     

A knowledge-based framework for intelligent-data migration

Abstract: The Object-Inferencing Framework (OIF) is a knowledge-based system developed for intelligent-data migration. The framework provides a mechanism to integrate relational data which represents a source model; a project-specific rulebase which specifies plausible migration scenarios; and a deduction system to facilitate the migration of source data to a new, complex target model. Typically, the target model includes constituents that possess both graphic and tabular components. Although the framework is experimental, industrial applications built upon OIF have been successfully deployed in scenarios in which the source data contained implicit information in that semantic relationships and structure conveyed by the data had to be inferred by a domain expert. This framework provides a substrate for migration from any unstructured or semi-structured data representation to a complex, semantically rich target data model. Examples of the migration of CAD data, which represents an electrical-distribution system, to a client-server based Automated Mapping/Facilities Management (AM/FM) platform are presented to convey the salient features of the design and utility of the OIF. Even though the examples are taken from a specific domain, the approach has potential applications in a myriad of domains, including business enterprises in which the migration of data created and managed by legacy systems to object-oriented and clientserver environments is an area of intense research and development.     

Packet triggered prediction based task migration for network-on-chip

The development of IC technology makes Network-on-Chip (NoC) an attractive architecture for future massive parallel systems. Task migration optimize the overall communication performance of NoCs since the changing phases of execution make static task mapping insufficient. It is well-known that the communication behavior of many applications are predictable, which makes it feasible to use prediction to guide task migration. The triggering of activating a task migration is also important. In this paper, we first defined and analyzed predictabilities of applications, and then compared different ways of triggering for migration. We then modified the Genetic Algorithm (GA) based task remapping and proposed two other task migration algorithms: Simple Exchange (SE) and Benefit Assess (BA). A mechanism called node lock is also used to reduce unnecessary and costly migrations. Simulation results on real applications from PARSEC benchmark suites show that the SE, BA and GA algorithms can reduce 21.4%, 34.0% and 34.9% of number of hops, and 17.3%, 27.2% and 26.3% in terms of average latency respectively, compared with the system without task migration; BA and SE reduce 72.0% and 78.7% of migrations without significant performance degradation compared with GA, and the node lock mechanism can further remove 37.3% and 46.0% of migrations while achieving almost the same performance.     

Data collection and restoration for heterogeneous process migration

This study presents a practical solution for data collection and restoration to migrate a process written in high‐level stack‐based languages such as C and Fortran over a network of heterogeneous computers. We first introduce a logical data model, namely the Memory Space Representation (MSR) model, to recognize complex data structures in process address space. Then, novel methods are developed to incorporate the MSR model into a process, and to collect and restore data efficiently. We have implemented prototype software and performed experiments on different programs. Experimental and analytical results show that: (1) a user‐level process can be migrated across different computing platforms; (2) semantic information of data structures in the process's memory space can be correctly collected and restored; (3) costs of data collection and restoration depend on the complexity of the MSR graph in the memory space and the amount of data involved; and (4) the implantation of the MSR model into the process is not a decisive factor of incurring execution overheads. With appropriate program analysis, we can practically achieve low overhead. Copyright © 2002 John Wiley & Sons, Ltd.     

MA计划方式迁移机制的对比分析

迁移技术是移动Agent（即Mobile Agent，简称MA）的关键技术之一。本文在概括了MA迁移过程并将MA的迁移与其它迁移技术做出比较的基础上，着重对比分析了MA计划方式的几种迁移机制，描述了各自的工作原理，特点，和可以进一步改进的地方。     

多群体云人口迁移算法

在原人口迁移算法的基础上,提出一种多群体云人口迁移算法(CMPMA)。利用云模型云滴的随机性和稳定倾向性的特点,通过改变云发生器的参数,由基本云发生器分别实现初始群体的生成和改进的人口流动操作,同时,增加了群最优记录,由多个人口群体同时进化寻优,显著提高了算法的运行效率和求解质量。通过典型函数和实例测试验证,算法是可行、有效的。     

Inferring patterns of internal migration from mobile phone call records: evidence from Rwanda

Understanding the causes and effects of internal migration is critical to the effective design and implementation of policies that promote human development. However, a major impediment to deepening this understanding is the lack of reliable data on the movement of individuals within a country. Government censuses and household surveys, from which most migration statistics are derived, are difficult to coordinate and costly to implement, and typically do not capture the patterns of temporary and circular migration that are prevalent in developing economies. In this paper, we describe how new information and communications technologies (ICTs), and mobile phones in particular, can provide a new source of data on internal migration. As these technologies quickly proliferate throughout the developing world, billions of individuals are now carrying devices from which it is possible to reconstruct detailed trajectories through time and space. Using Rwanda as a case study, we demonstrate how such data can be used in practice. We develop and formalize the concept of inferred mobility, and compute this and other metrics on a large data set containing the phone records of 1.5 million Rwandans over four years. Our empirical results corroborate the findings of a recent government survey that notes relatively low levels of permanent migration in Rwanda. However, our analysis reveals more subtle patterns that were not detected in the government survey. Namely, we observe high levels of temporary and circular migration, and note significant heterogeneity in mobility within the Rwandan population. Our goals in this research are thus twofold. First, we intend to provide a new quantitative perspective on certain patterns of internal migration in Rwanda that are unobservable using standard survey techniques. Second, we seek to contribute to the broader literature by illustrating how new forms of ICT can be used to better understand the behavior of individuals in developing countries.     

虚拟机动态迁移远程属性证明简

随着互联网和企业提高资源利用率,其基础技术虚拟化技术发展迅速。同时虚拟化的动态迁移,是实现资源调度灵活性和可行性必要条件。动态迁移涉及方面广,导致安全问题突出。在Xen虚拟化的平台下,引入了虚拟PCR（vPCR）和属性的概念,利用可信属性认证协议将数据与系统安全属性封装起来保护,同时保护多个虚拟机系统中数据的安全,不受虚拟机系统配置变化的影响,保证虚拟机动态迁移安全性。     

面向对象XML的对象迁移方法研究

针对面向对象的XML数据的对象迁移问题,提出基于集中式和分布式两种存储模式下的对象迁移方法,解决了对象标识符模糊性问题。集中式存储模式对象的OID是唯一的,但是在集中式存储模式中更新已存在的对迁移对象的引用代价很大;分布式存储模式对象的OID是多重的,但对象迁移的代价相对较小。