论文标题
仔细观察轻巧的图形重新排序
A Closer Look at Lightweight Graph Reordering
论文作者
论文摘要
Graph Analytics在金融,网络和业务物流等领域的一系列应用程序。图形分析域中使用的图形的共同属性是顶点连接的幂律分布,其中少数顶点负责图形中所有连接的高分子。这些富有连接的(热)顶点固有地表现出很高的重复使用。然而,它们在记忆中的稀疏分布导致片上缓存的严重缺乏利用。先前的作品提出了轻巧的偏斜顶点重新排序,将热门顶点彼此相邻,从而减少了热门顶点的高速缓存足迹。但是,这样做时,它们可能会无意间破坏图中固有的社区结构,这可能会否定从热门顶点减少的占用的绩效中获得的绩效收益。 在这项工作中,我们研究了现有的重新排序技术,并证明了减少热门顶点的高速缓存足迹和保留原始图形结构之间的固有张力。我们量化了不同图数据集的图形结构中断导致的潜在性能损失。我们进一步表明,使用细粒度重新排序的重新排序技术在更高级别的缓存中显着增加了失误,即使它们减少了最后级别的缓存中的错过。 为了克服现有的重新排序技术的局限性,我们提出了基于学位的分组(DBG),这是一种新型的轻质重新排序技术,它采用粗粒度的重新排序以在很大程度上保留图形结构,同时降低热门顶点的高速公路足迹。我们对各种图形应用程序和数据集组合的40个组合的评估表明,与没有重新排序的基线相比,DBG的平均应用程序速度为16.8%,而表现最好的现有轻质技术的平均应用程序为11.6%。
Graph analytics power a range of applications in areas as diverse as finance, networking and business logistics. A common property of graphs used in the domain of graph analytics is a power-law distribution of vertex connectivity, wherein a small number of vertices are responsible for a high fraction of all connections in the graph. These richly-connected (hot) vertices inherently exhibit high reuse. However, their sparse distribution in memory leads to a severe underutilization of on-chip cache capacity. Prior works have proposed lightweight skew-aware vertex reordering that places hot vertices adjacent to each other in memory, reducing the cache footprint of hot vertices. However, in doing so, they may inadvertently destroy the inherent community structure within the graph, which may negate the performance gains achieved from the reduced footprint of hot vertices. In this work, we study existing reordering techniques and demonstrate the inherent tension between reducing the cache footprint of hot vertices and preserving original graph structure. We quantify the potential performance loss due to disruption in graph structure for different graph datasets. We further show that reordering techniques that employ fine-grain reordering significantly increase misses in the higher level caches, even when they reduce misses in the last-level cache. To overcome the limitations of existing reordering techniques, we propose Degree-Based Grouping (DBG), a novel lightweight reordering technique that employs a coarse-grain reordering to largely preserve graph structure while reducing the cache footprint of hot vertices. Our evaluation on 40 combinations of various graph applications and datasets shows that, compared to a baseline with no reordering, DBG yields an average application speed-up of 16.8% vs 11.6% for the best-performing existing lightweight technique.