通信竞争的混合关键级系统多DAG动态调度策略

以多DAG模型研究通信竞争的混合关键级系统(mixed-criticality systems)的调度问题是适应现代汽车电子系统异构化和分布式的需要.首先实现通信竞争环境下“向上排序值(upward rank value)”和“最早完成时间(earliest finish time)”中时间的精确分析,以适应系统中计算与网络均异构,且任务与消息的同步特征.接着提出公平策略的多DAG动态任务与消息调度F_MDDTMS算法,以降低系统的调度长度;提出关键级策略的多DAG动态任务与消息调度C_MDDTMS算法,以确保高关键级应用的实时性;结合F_MDDTMS算法和C_MDDTMS算法,提出混合关键级策略的多DAG动态任务与消息调度MC_MDDTMS算法,既确保混合关键级系统中高关键级应用的实时性,又使得低关键级应用得到积极的处理.实例分析和实验结果验证了提出的算法在调度长度、不公平性、最差响应时间和实时性上的优越性.     

考虑能耗与工时恶化作用下的并行机调度优化

在热处理加工环境中,工件温度随着其开工时刻的延误不断下降,为了能够正常加工不得不保温或重新加热.针对这一现象,本文考虑了能耗与工时恶化作用下的并行机调度问题,以最小化总拖期和能耗为目标构建了混合整数规划模型.由于问题的复杂性,提出了一种遗传变搜索算法,其通过遗传操作获得变邻域搜索操作的解集,而后使用变邻域结构进行寻优操作.算例测试表明：较之传统遗传算法以及数学规划器Gurobi的计算结果,所提出的算法可以有效减少综合能耗和拖期成本.     

超级计算机作业运行稳定性分析

通过作业日志分析和考核实验方式,对超级计算机并行作业运行稳定性进行了分析。日志分析结果表明,并行作业运行的稳定性会随作业执行时间的增长、作业使用CPU数的增多而下降;当并行作业的计算量达到105CPU小时量级,超过20%的作业会因系统故障而中止。考核实验结果表明,使用数千CPU的并行作业很容易受到多种因素的干扰而中止,很难持续运行超过24小时。最后给出了有关超级计算机稳定性改进、系统管理使用和并行程序研制的几点建议。     

Efficient Multiple Multicast on Heterogeneous Network of Workstations

In recent years, network of workstations/PCs (so called NOW) are becoming appealing vehicles for cost-effective parallel computing. Due to the commodity nature of workstations and networking equipment, LAN environments are gradually becoming heterogeneous. The diverse sources of heterogeneity in NOW systems pose a challenge on the design of efficient communication algorithms for this class of systems. In this paper, we propose efficient algorithms for multiple multicast on heterogeneous NOW systems, focusing on heterogeneity in processing speeds of workstations/PCs. Multiple multicast is an important operation in many scientific and industrial applications. Multicast on heterogeneous systems has not been investigated until recently. Our work distinguishes itself from others in two aspects: (1) In contrast to the blocking communication model used in prior works, we model communication in a heterogeneous cluster more accurately by a non-blocking communication model, and design multicast algorithms that can fully take advantage of non-blocking communication. (2) While prior works focus on single multicast problem, we propose efficient algorithms for general, multiple multicast (in which single multicast is a special case) on heterogeneous NOW systems. To our knowledge, our work is the earliest effort that addresses multiple multicast for heterogeneous NOW systems. These algorithms are evaluated using a network simulator for heterogeneous NOW systems. Our experimental results on a system of up to 64 nodes show that some of the algorithms outperform others in many cases. The best algorithm achieves completion time that is within 2.5 times of the lower bound.     

面向大规模计算集群的多轨分割网络

在千万亿次规模的系统中,互连网络设计面临新的挑战.高性能节点和大规模是构建千万亿次系统的主要技术趋势,不断提高的节点计算能力要求互连网络提供更高的性能,而不断增大的规模又对互连网络扩展性提出了更高的要求.此外,随着系统规模的增大,集合通信的执行时间也在不断增长,制约了应用的扩展性,集合通信的性能需要得到进一步优化.除性能之外,可靠性问题也随着系统规模的扩大而日益严重.而随着计算节点性能的不断提高,互连网络逐渐成为限制大规模计算机系统性能的瓶颈.互连网络核心部件交换芯片可提供的聚合网络带宽受到工艺和封装技术的限制.从网络结构与交换机结构的协同设计思想出发,提出了一种在交换机聚合带宽限定的条件下多轨分割网络结构和设计方法.通过数学建模和网络模拟仿真,分析了该多轨分割网络的性能边界.评测结果表明:该网络可将短消息(长度小于128B)的平均延迟性能提高10倍以上,为以短消息占多数的数据中心网络的性能优化提供了新思路.     

独立多处理机任务静态调度问题的近似算法

研究独立多处理机任务静态调度问题P_m|fix|C_max,即在m个处理机系统中调度n个多处理机任务,每个任务指派到所需一组处理机上不可剥夺地执行.该问题应用广泛但早已证明为NP难问题,而且也不存在常数近似算法.分析了问题P_m|fix|C_max和其中所有任务都是单位处理机时间的特殊情形P_m|fix,p=1|C_max的调度,并利用实例划分(split scheduling,简称SS)、首次满足优先(first fit,简称FF)和最大宽度优先(large wide first,简称LWF)等方法,构造了问题P_m|fix,p=1|C_max的√2m +1近似算法和问题P_m|fix|C_max的2√m 近似算法,优于目前已有文献的最好结果.     

面向云计算的期限约束的MapReduce作业调度方法

提出一种面向异构云计算环境的截止时间约束的MapReduce作业调度方法。使用加权偶图建模MapReduce作业调度问题,将Map任务及Reduce任务与资源槽分为2个节点集合,连接2个节点集合的边的权重为任务在资源槽上的执行时间。进而,使用整数线性规划求解最小加权偶图匹配,从而得到任务到资源槽的调度方案。本文考虑了云计算环境下异构节点任务处理时间的差异性,在线动态评估和调整任务的截止时间,从而提升了MapReduce作业处理的性能。实验结果表明,所提出的方法缩短了作业数据访问的时间,最小化了截止时间冲突的作业数量。     

Multisite co-allocation scheduling algorithms for parallel jobs in computing grid environments

Cooperation of multi-domain massively parallel processor systems in com- puting grid environment provides new opportunities for multisite job scheduling. At the same time, in the area of co-allocation, heterogeneity, network adaptability and scalability raise the challenge for the international design of multisite job scheduling models and algorithms. It presents multisite job scheduling schema through the introduction of mul- tisite job scheduling model and the performance model under the grid environment. It introduces two job multisite and cooperative scheduling models and algorithms with the core of the optimal and greedy-heuristic resource selection strategies. Meanwhile, com- pared with single and multisite cooperative scheduling models and algorithms introduced by Sabin, Yahyapour and other persons, the validity and advance of the scheduling model and the performance model herein are proved.     

分布异构工作站上的任务调度算法

讨论了在一个由高速局域网连接的高性能异构工作站平台上，如何有效地利用空闲工作站来求解计算密集型任务矩阵相乘的问题，为了获得较好的并行计算性能，文中给出了一个异构工作站群之间任务调度的模型和算法，算法中考虑了并行计算中协作任务间的通信时间、数据加栽时间、结果收集时间和各个异构工作站的任务计算时间，通过这个模型，可以在所有可利用的工作站集合中找出最适合的子集，获得最短的执行时间．     

Multi-Dimensional Scheduling for Real-Time Tasks on Heterogeneous Clusters

Multiple performance requirements need to be guaranteed in some real-time applications such as multimedia data processing and real-time signal processing in addition to timing constraints.Unfortunately,most conventional scheduling algorithms only take one or two dimensions of them into account.Motivated by this fact,this paper investigates the problem of providing multiple performance guarantees including timeliness,QoS,throughput,QoS fairness and load balancing for a set of independent tasks by dynamic ...