面向神威高性能多核处理器的并行编译优化方法

在神威高性能多核服务器上,自动并行化编译系统为识别和申明程序中的并行性,产生的OpenMP程序没有经过充分的优化,其采用简单的fork-join模型,存在大量的并行循环嵌套,导致运行效率低。为提升自动并行化编译系统产生的OpenMP程序的运行效率,提出一种并行域重构优化技术。并行域重构技术通过合并程序中的并行域和扩展嵌套循环中的并行域范围,减少OpenMP程序的并行域数目,降低线程组频繁创建和合并等控制开销,将简单fork-join模型的OpenMP程序转换为性能更为高效的单程序多数据模型的OpenMP程序。实验结果表明,在新一代神威高性能多核服务器SW1621平台上,并行域重构技术在NPB3.3-OMP测试集和SPEC OMP2012测试集上的运行效率分别提高了10.77%和7.94%的,可有效提升自动并行化编译系统OpenMP程序的执行效率。     

半透膜仪采集空气中多氯联苯采样速度与其结构和性质定量构效关系研究

根据MOPAC2009软件包中PM6算法得到的分子描述符研究半透膜仪(SPMDs)采集大气中多氯联苯(PCBs)采样速度(R_(air))的定量构效关系(QSPR)模型,并分析影响R_(air)的关键因素。以半经验PM6算法得到的分子量子化学描述符作为预测变量,采用偏最小二乘算法(PLS)构建了R_(air)的QSPR模型。根据交叉验证,所得到的最佳模型中PLS成分解释的因变量的累积变异(Q~2_(cum))为0.683,这表明该模型具有良好的预测能力和稳健性。通过外部验证和将实验测得的R_(air)与预测得到的R_(air)进行比较,对所构建模型的稳定性和可靠性进行了验证,结果表明无论是训练组还是预测组,其预测值与实测值间均具有较好的线性关系,线性相关系数均大于0.8376。对PCBs采样速度R_(air)的主要影响因素为PCBs与SPMDs中甘油三油酸酯分子间的相互作用大小和为将PCBs溶解在甘油三油酸酯中形成洞穴所需能量要求。     

Massively parallel implementation of the mesoscale compressible community model

Computational fluid dynamics and meteorology in particular are among the major consumers of high performance computer technology. The next generation of atmospheric models will be capable of representing fluid flow phenomena at very small scales in the atmosphere. The mesoscale compressible community (MC2) model represents one of the first successful applications of a semi-implicit, semi-Lagrangian scheme to integrate the compressible governing equations for atmospheric flow in a limited area domain. A distributed-memory SPMD implementation of the MC2 model is described and the convergence rates of various parallel preconditioners for a Krylov type GMRES elliptic solver are reported. Parallel performance of the model on the Cray T3E MPP and NEC SX-4/32 SMP is also presented.     

时域有限差分法并行计算中的区域划分及负载平衡

本文讨论了利用网络进行时域有限差分法FDTD并行计算时需要解决的两个关键问题 ,区域划分策略及负载平衡策略。并结合实例进行了试验。最后 ,给出了平面光波导场域FDTD并行计算的实验结论     

Processor preallocation and load balancing of DOALL loops

Load balance is important because it may affect the speedup attained through the concurrent execution of loop iterations on a parallel processor. We study loop load balance in the context of the well-known Perfect benchmarks. Several static and dynamic characteristics of the Perfect benchmark DOALL loops are observed and interpreted. Thelate arrival of processors is noted as a major source of load imbalance. This observation suggested the idea ofprocessor preallocation. An analytic cost model is presented and the advantages of processor preallocation are demonstrated by experimental evaluation on a CRAY Y-MP8 under the Unicos operating system.     

共享内存结构并行程序的编译器优化

共享内存结构上的程序自动并行化通常实现循环级并行,采用fork-join执行模式,并行性能有待提高。论文结合fork-join和SPMD两种执行模式的优势,在并行化编译过程中通过并行区合并和扩展,实现fork-join和SPMD混合执行模式,并在SPMD并行区中实现了基于跨处理器相关图的barrier同步优化。分析验证表明,这些优化策略减少了并行区和barrier同步的数目,有效地提高了生成并行程序的性能。     

基于HPF的地震资料并行处理系统研究与实现

文中首先分析了地震资料并行处理的必要性，在介绍HPF高性能并行语言的特点后，着重讨论了p-HPF编译系统的体系结构与关键技术，然后，在分析地震资料自身特征和处理过程模块化程序设计的特点后，给出了地震资料处理的并行策略和一般SPMD程序的实现框图，最后，用一个简单的例子展示了HPF程序对于不同数据规模的并行效率，并用实际地震资料实现了大规模并行处理。     

淮河沙颍河支流水质预报模型的参数率定

水质模型的参数率定一直是水质预报的难点。由于要求模型计算结果准确，故必须对每个参数反复多次计算才能给出一个较为可用的参数值。用传统的串行计算方法来处理参数率定问题，其计算时间过长，无法快速给出准确的模型。文章利用已有的数据和经验，根据沙颖河具体的水质和应用特点，在国内首次提出了采用基于并行计算技术的高性能计算方法，对沙颖河支流水质模型进行多参数率定的方案，并在曙光系列并行机上得以实现。结果表明：其率定的准确性大大优于常规率定，并缩短了整个模型的建模时间，由此为模型的快速应用提供了可靠的参数依据。     

Armadillo generation distributed system with geranium Cadcam cluster for solving 2D telegraphic problem

In this paper, the parallel implementation of the iterative alternating direction explicit method by D'Yakonov (IADE-DY) and the Mitchell and Fairweather double sweep method (DS-MF) compared with the alternative direction implicit (ADI) method for solving the 2D telegraphic problem on a distributed system of Armadillo cluster and geranium Cadcam cluster using the parallel virtual machine and message passing interface is presented. We implement the scheduling of n tridiagonal system of equations with the above methods to show improvement on speedup and efficiency with parallel strategies across the two platforms. The single program multiple data model was employed for the implementation. The IADE-DY, DS-MF and ADI are developed by the splitting of the implicit equation using the finite difference discretization on the 2D telegraphic problem. The implementation is discussed in relation to means of the performance parallel strategies and analysis. The model enhances overlap communication and computation to avoid unnecessary synchronization, hence, the method yields significant speedup by the use of the non-blocking communication. We present some analyses that are helpful for speedup and efficiency.     

PVM环境下SPMD程序模式探讨

介绍ＰＶＭ环境下的ＳＰＭＤ程序模式,并结合程序自动并行化模型ＡＰＭ,提出了克服ＳＰＭＤ不足之处的思想,描述了改进后的ＳＰＭＤ程序模式——ａＳＰＭＤ程序模式。该模式既有ＳＰＭＤ模式的特点,又有Ｍａｓｔｅｒ－Ｓｌａｖｅ模式的特点。文中还给出了一个用ＡＰＭ模型生成的ａＳＰＭＤ模式并行程序的实际运行效率以及ａＳＰＭＤ模式并行程序与ＳＰＭＤ模式并行程序运行时间。