Aftermath: A graphical tool for performance analysis and debugging of fine-grained task-parallel programs and run-time systems

International audienceWe present Aftermath, an open source graphical tool designed to assist inthe performance debugging process of task-parallel programs byvisualizing, filtering and analyzing execution traces interactively.To efficiently exploit increasingly complex and concurrent hardwarearchitectures, both the application and the run-time system thatmanages task execution must be highly optimized. However, detectingperformance anomalies is challenging as bottlenecks can arise directlyfrom the application, the run-time or interaction with the hardware.In Aftermath, key metrics and indicators, such as task duration, stateinformation, hardware performance counter values and data exchangescan be visualized jointly, aggregated and related to the machine'stopology. The tool supports traces of up to several gigabytes, withfast and intuitive navigation and on-line generation of new derivedmetrics. As it has proven invaluable to optimize both OpenStream'srun-time and applications, we illustrate Aftermath on genuine casesencountered in the OpenStream project