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arXiv 1609.01490cs.DC
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三角域上的非线性GPU线程映射

A Non-linear GPU Thread Map for Triangular Domains

Cristóbal A. Navarro, Benjamín Bustos, Nancy Hitschfeld

摘要:

在GPU计算流水线中存在一个阶段,其中\textit{parallel space}中的线程块网格被映射到\textit{data space}中的问题域。由于并行空间被限制为盒型几何,因此映射方法通常是覆盖$p$维数据空间的$k$维边界盒(BB)。落在域内的线程执行计算,而落在域外的线程在运行时被丢弃。在这项工作中,我们研究的情况下,有效地映射线程到三角域的问题,并提出了一个块空间的线性映射$λ(ω)$,下三角矩阵的属性的基础上,减少了不必要的线程从$\mathcal{O}(n^2)$到$\mathcal{O}(n)$的数量。全局存储器访问的性能结果显示,$18\%$相对于\textit{bounding-box}方法的改进,将$λ(ω)$置于第二位,低于\textit{rectangular-box}方法,高于\textit{recursive-partition}和\textit{upper-triangular}方法。对于共享内存场景,$λ(ω)$是在保持线程局部性的同时实现$7\%$性能改进的最快方法。在这项工作中获得的结果使$λ(ω)$一个有趣的地图,高效的GPU计算的并行问题,定义一个三角形域或没有邻居的相互作用。扩展到四面体域进行了分析,与应用程序的三重相互作用的n体应用程序。

英文摘要:

There is a stage in the GPU computing pipeline where a grid of thread-blocks, in \textit{parallel space}, is mapped onto the problem domain, in \textit{data space}. Since the parallel space is restricted to a box type geometry, the mapping approach is typically a $k$-dimensional bounding box (BB) that covers a $p$-dimensional data space. Threads that fall inside the domain perform computations while threads that fall outside are discarded at runtime. In this work we study the case of mapping threads efficiently onto triangular domain problems and propose a block-space linear map $λ(ω)$, based on the properties of the lower triangular matrix, that reduces the number of unnnecessary threads from $\mathcal{O}(n^2)$ to $\mathcal{O}(n)$. Performance results for global memory accesses show an improvement of up to $18\%$ with respect to the \textit{bounding-box} approach, placing $λ(ω)$ on second place below the \textit{rectangular-box} approach and above the \textit{recursive-partition} and \textit{upper-triangular} approaches. For shared memory scenarios $λ(ω)$ was the fastest approach achieving $7\%$ of performance improvement while preserving thread locality. The results obtained in this work make $λ(ω)$ an interesting map for efficient GPU computing on parallel problems that define a triangular domain with or without neighborhood interactions. The extension to tetrahedral domains is analyzed, with applications to triplet-interaction n-body applications.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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