A Remote Procedure Call Facility for Interconnecting Heterogeneous Computer Systems

Heterogeneity in hardware and software is an inevitable consequence of experimental computer research. At the University of Washington, the Heterogeneous Computer Systems (HCS) project is a major research and development effort whose goal is to simplify the interconnection of heterogeneous computer systems.     

OpenCL: A Parallel Programming Standard for Heterogeneous Computing Systems

We provide an overview of the key architectural features of recent microprocessor designs and describe the programming model and abstractions provided by OpenCL, a new parallel programming standard targeting these architectures.     

A Novel State Transition Method for Metaheuristic-Based Scheduling in Heterogeneous Computing Systems

Much of the recent literature shows a prevalance in the use of metaheuristics in solving a variety of problems in parallel and distributed computing. This is especially ture for problems that have a combinatorial nature, such as scheduling and load balancing. Despite numerous efforts, task scheduling remains one of the most challenging problems in heterogeneous computing environments. In this paper, we propose a new state transitionscheme , called the Duplication-based State Transition (DST) method specially designed for metaheuristics that can be used for the task scheduling problem in heterogeneous computing environments. State transition in metaheuristics is a key component that takes charge of generating variants of a given state. The DST method produces a new state by first overlapping randomly generated states with the current state and then the resultant state is refined by removing ineffectual tasks. The proposed method is incorporated into three different metaheuristics: genetic algorithms (GAs), simulated annealing (SA), and artificial immune system (AISs). They are experimentally evaluated and are also compared with existing algorithms. The experimental results confirm DST's promising impact on the performance of metaheuristics.     

异构多处理器系统Cache一致性解决方案

SoC技术的发展使多个异构的处理器集成到一个芯片成为可能,这种结构已成为提高微处理器性能的重要途径.与传统的多处理器系统一样,Cache一致性问题也是片内异构多处理器系统必须首先解决的问题.本文在分析Cache一致性问题的基础上,对采用不同监听协议的多处理器的集成,以牺牲简单的硬件为代价来完成一致性协议的转化.将此方法并入多处理器芯片封装内来管理,可保证在异构多处理器系统中数据的一致性.     

Fault-Tolerant Dynamic Rescheduling for Heterogeneous Computing Systems

As the scale and complexity of heterogeneous computing systems grow, failures occur frequently and have an adverse effect on solving large-scale applications. Hence, fault-tolerant scheduling is an imperative step for large-scale computing systems. The existing fault-tolerant scheduling algorithms belong to static scheduling, and they allocate multiple copies of each task to several processors no matter whether processor failures affect the execution of tasks. Such active replication strategies not only waste resource but also sacrifice the makespan. What is more, they cannot guarantee the successful execution of applications. In this paper, we propose a fault-tolerant dynamic rescheduling algorithm named FTDR, which can overcome above drawbacks. FTDR keeps listening to the processor failure, and reschedules the suspended tasks once failures occur. Because FTDR reschedules the tasks that are suspended because of failures, it can tolerate an arbitrary number of failures. Randomly generated DAGs are tested in our experiments. Experimental results show that the proposed algorithm achieves good performance in terms of makespan and resource consumption compared with its direct competitors.     

A Model for Query Decomposition and Answer Construction in Heterogeneous Distributed Database Systems

The problem of retrieving information from a collection of heterogeneous distributed databases has attracted a number of solutions. However, the task of integrating established database systems is complicated not only by the differences between the database systems themselves, but also by the differences in structure and semantics of the information contained within them. The problem is exacerbated when one needs to provide access to such a system for naive end-users.This paper is concerned with a Knowledge-Based Systems approach to solving this problem for clearly bounded situations, in which both the domain and the types of query are constrained. At the user interface, dialogue is conducted in terms of concepts with which the user is familiar, and these are then mapped into appropriate database queries. To achieve this a model for query decomposition and answer construction has been used. This model is based around the development of an Intensional Structure containing information necessary for the recapture of semantic information lost in the query decomposition process and required in the answer construction process. The model has been successfully implemented in combination with an embedded KBS, within a five-layer representation model.     

Distributed Coordination in Heterogeneous Multi-Robot Systems

Coordination in multi-robot systems is a very active research field in Artificial Intelligence and Robotics, since through coordination one can achieve a more effective execution of the robots' tasks. In this paper we present an approach to distributed coordination of a multi-robot system that is based on dynamic role assignment. The approach relies on the broadcast communication of utility functions that define the capability for every robot to perform a task and on the execution of a coordination protocol for dynamic role assignment. The presented method is robust to communication failures and suitable for application in dynamic environments. In addition to experimental results showing the effectiveness of our approach, the method has been successfully implemented within the team of heterogeneous robots Azzurra Robot Team in a very dynamic hostile environment provided by the RoboCup robotic soccer competitions.     

异构系统的异步应用级Checkpointing技术

应用级checkpointing技术是同构系统上最为常用和成熟的容错技术,但在异构系统下的应用还处于起步阶段,还没有一套严谨合理的针对异构系统架构和故障模型特点的实现方案和配置方法。针对这一现况,本文基于CUDA异构系统的体系结构和编程模型,对CUDA程序在CPU和GPU上的执行模式进行分析,提出了一种面向异构系统应用级checkpointing技术的异步执行机制,并基于这一机制对异构系统的检查点优化设置问题进行讨论,设计了一套优化方案。最后在CUDA平台下通过三个实例验证了这一技术的可行性和实用性,并进行了性能评估。结果表明,这种面向CPU-GPU的异构系统的应用级checkpointing异步执行机制是行之有效的,相比CPU-GPU同步执行的checkpointing机制在设置上更为灵活,优化空间更大。而本文基于这一机制所提出的检查点优化设置方法也有效地减少了check-pointing的开销,从而获得了更高的容错性能。     

Distributed Control: A Sequentially Semi-Separable Approach for Spatially Heterogeneous Linear Systems

We consider the problem of designing controllers for spatially-varying interconnected systems distributed in one spatial dimension. The matrix structure of such systems can be exploited to allow fast analysis and design of centralized controllers with simple distributed implementations. Iterative algorithms are provided for stability analysis, $H_{infty}$ analysis and sub-optimal controller synthesis. For practical implementation of the algorithms, approximations can be used, and the computational efficiency and accuracy are demonstrated on an example.      

Architectural Exploration of Heterogeneous Multiprocessor Systems for JPEG

Multicore processors have been utilized in embedded systems and general computing applications for some time. However, these multicore chips execute multiple applications concurrently, with each core carrying out a particular task in the system. Such systems can be found in gaming, automotive real-time systems and video / image encoding devices. These system are commonly deployed to overcome deadline misses, which are primarily due to overloading of a single multitasking core. In this paper, we explore the use of multiple cores for a single application, as opposed to multiple applications executing in a parallel fashion. A single application is parallelized using two different methods: one, a master-slave model; and two, a sequential pipeline model. The systems were implemented using Tensilica’s Xtensa LX processors with queues as the means of communications between two cores. In a master-slave model, we utilized a course grained approach whereby a main core distributes the workload to the remaining cores and reads the processed data before writing the results back to file. In the pipeline model, a lower granularity is used. The application is partitioned into multiple sequential blocks; each block representing a stage in a sequential pipeline. For both models we applied a number of differing configurations ranging from a single core to a nine-core system. We found that without any optimization for the seven core system, the sequential pipeline approach has a more efficient area usage, with an area increase to speedup ratio of 1.83 compared to the master-slave approach of 4.34. With selective optimization in the pipeline approach, we obtained speed ups of up to 4.6 × while with an area increase of only 3.1 × (area increase to speedup ratio of just 0.68). National ICT Australia is funded through the Australian Government’s Backing Australia’s Ability initiative, in part through the Australian Research Council.     

Towards Ontology-driven Knowledge Synthesis for Heterogeneous Information Systems

Information integration enables delivery of the right information to the right user in a timely manner giving manufacturers a competitive edge in today’s global manufacturing market. However, as enterprise information is usually aggregated from a variety of heterogeneous information sources, without using an adequate integration framework it is difficult to extract pertinent information and apply current knowledge to assessing production situations and making informed decisions. This paper investigates a method of facilitating knowledge synthesis in a distributed computing environment. A formal model of domain ontology and knowledge base is presented, which aims at providing a vehicle for representing information and knowledge using a common shared semantics in a given application domain. As a result, a common knowledge representation based architecture is proposed, creating a foundation for establishing a systematic approach for ease of knowledge synthesis in a manufacturing environment     

异构系统中实体识别研究

已有的实体识别技术可以根据名称、地址进行摘词、排序,从而进行匹配,文章就不同商业企业中多个系统之间的数据集成时的数据匹配工作提出了一种基于线性相关性分析的实体识别方法。在多个系统均存在主数据和与主数据相关的记录项时,通过对记录项的平滑处理后,计算不同系统数据之间的线性相关性,对计算出来的相关性值进行分析,从而得到匹配关系的建议解。最后对相同实体识别研究方向进行了展望。     

多复杂异构系统的信息融合

μXL集散控制系统、Bently振动监测系统和WindowsNT计算机网络系统是各自相对独立、结构不同的复杂系统.本文利用LabWindows/CVI虚拟仪器开发平台,采用虚拟仪器技术,以μXL网卡为媒介,借助于MS-Excel,通过动态数据交换手段实现了PC机自动、连续、自主地从μXL系统获取数据,并通过高速数据采集卡,从Bently振动监测系统同步获取多通道振动信号,以WindowsNT网为纽带,实现了Bently振动监测系统、μXL集散控制系统和WindowsNT计算机网络系统的多复杂异构系统的信息融合,并结合工程实例,详细讨论该方法的具体应用.     

Efficient and Scalable Consistency Maintenance for Heterogeneous Peer-to-Peer Systems

Consistency maintenance mechanism is necessary for the emerging Peer-to-Peer applications due to their frequent data updates. Centralized approaches suffer single point of failure, while previous decentralized approaches incur too many duplicate update messages because of locality-ignorant structures. To address this issue, we propose a scalable and efficient consistency maintenance scheme for heterogeneous P2P systems. Our scheme takes the heterogeneity nature into account and forms the replica nodes of a key into a locality-aware hierarchical structure, in which the upper layer is DHT-based and consists of powerful and stable replica nodes, while a replica node at the lower layer attaches to a physically close upper layer node. A d-ary update message propagation tree (UMPT) is dynamically built upon the upper layer for propagating the updated contents. As a result, the tree structure does not need to be maintained all the time, sav-ing a lot of cost. Through theoretical analyses and comprehensive simulations, we examine the efficiency and scalability of this design. The results show that, compared with previous designs, especially locality-ignorant ones, our approach is able to reduce the cost by about 25-67 percent.     

一种新的异构实时分布式系统的容错调度算法

一般来说,异构分布式实时系统中任务的周期并不完全相同且任务的时限不等于它们的周期,同时系统中还有一些无容错需求的任务.因此现有的任务调度算法一般不能满足这些要求.针对这类系统,在结合基版本/副版本技术和EDF算法的基础上,给出了一种新的容错调度算法.该算法由两部分组成：任务分配调度算法和单处理器调度算法.对于单处理器调度算法,本文采用了EDF算法;在此基础上,给出一种启发式静态任务分配算法.分析了系统的可调度性,给出了任务可调度条件和基版本/副版本时限的设置方法.仿真结果表明,这种算法是有效的.