Ocelotl: Large Trace Overviews Based on Multidimensional Data Aggregation

International audiencePerformance analysis of parallel applications is commonly based on execution traces that might be investigated through visualization techniques. The weak scalability of such techniques appears when traces get larger both in time (many events registered) and space (many processing elements), a very common situation for current large-scale HPC applications. In this paper we present an approach to tackle such scenarios in order to give a correct overview of the behavior registered in very large traces. Two configurable and controlled aggregation-based techniques are presented: one based exclusively on the temporal aggregation, and another that consists in a spatiotemporal aggregation algorithm. The paper also details the implementation and evaluation of these techniques in Ocelotl, a performance analysis and visualization tool that overcomes the current graphical and interpretation limitations by providing a concise overview registered on traces. The experimental results show that Ocelotl helps in detecting quickly and accurately anomalies in 8 GB traces containing up to two hundred million of events