栅格地理计算并行算子对区域计算算法并行化的可用性分析——以多流向算法为例  

Parallelization of Regional Operation Algorithm Using Parallel Raster-based Geocomputation Operators

作　　者：艾贝贝 秦承志[1,3] 朱阿兴[1,3,4] 

机构地区：[1]中国科学院地理科学与资源研究所资源与环境信息系统国家重点实验室,北京100101 [2]中国科学院大学资源与环境学院,北京100049 [3]南京师范大学地理科学学院江苏省地理信息资源开发与利用协同创新中心,南京210023 [4]Department of Geography,University of Wisconsin-Madison

出　　处：《地球信息科学学报》2015年第5期562-567,共6页Journal of Geo-information Science

基　　金：国家自然科学基金项目(41422109);国家科技支撑计划项目(2013BAC08B03-4)

摘　　要：栅格地理计算并行编程库的研发有助于实现对栅格地理计算算法的并行化。在现有的研究中,Qin等(2014)设计并初步研发的栅格地理计算并行算子(Pa RGO),在设计思路上能较好地隐藏与并行编程软硬件环境相关的复杂细节,实现栅格地理计算通用步骤的并行化,且较其他类似思路的编程库而言,Pa RGO能兼容多种常用的并行计算平台,具有明显优势。但Pa RGO目前在设计上仅直接支持本地、邻域及全局计算特点的栅格地理计算算法并行化,对于更为复杂的区域计算特点算法并行化的支持能力尚未探究。对此,本文选取栅格数字地形分析中具有区域计算特点、递归设计的多流向算法为算例,利用Pa RGO进行并行化设计、实现及测试,以计算时间、相对加速比和相对并行效率为定量指标。通过可运行性和并行性能进行评价,结果表明:Pa RGO虽然不能直接支持对递归的多流向算法进行并行化,但在根据多流向计算的原理将该递归算法转变为非递归的设计之后,可将算法由原区域计算改造为邻域迭代计算,就能利用Pa RGO实现并行化,并得到较好的并行效果。在集群环境下,MPI版本并行程序的并行效果优于MPI/Open MP混合版本。Parallel raster-based programming libraries have been proposed to make the details of parallel pro- gramming and the parallel hardware architecture to be transparent to users in some degrees. Thus these libraries can facilitate the development of parallel programs of raster-based geocomputation. Among the existing parallel programming libraries, parallel raster-based geocomputation operators （PaRGO）, which is recently proposed by Qin et al, shows great advantages. This is not only because PaRGO encapsulates the general steps in parallel ras- ter-based geocomputation, but also because PaRGO is compatible with multiple commonly used parallel comput- ing platforms. Currently, PaRGO is designed for supporting local operation, focal operation and global operation directly. However, the availability of PaRGO for supporting regional operation in raster-based geocomputation has not been evaluated. In this paper, we evaluate PaRGO to testify its performance in this circumstance by using a multiple-flow-direction algorithm as a representation of the regional operation. Different versions of PaRGO- based parallel programs for this algorithm are tested on a symmetrical multiprocessing （SMP） cluster and evalu- ated from two aspects： the performability and the parallel efficiency. The experimental results show that the cur- rent PaRGO cannot directly support the parallelization of regional operations. But it can be supportive when the regional operation is transformed into an iteration process of focal operation. On a SMP cluster, MPI-version par- allel program performs better than MPI/OpenMP-version parallel program.

关 键 词：栅格地理计算 并行计算 栅格地理计算并行算子 区域计算 多流向算法 

分 类 号：P208[天文地球—地图制图学与地理信息工程] TP338.6[天文地球—测绘科学与技术]