Visualizing Application Behavior on Superscalar Processors

The advent of superscalar processors with out-of-order execution makes it increasingly difficult to determine how well an application is utilizing the processor and how to adapt the application to improve its performance. In this paper, we describe a visualization system for the analysis of application behavior on superscalar processors. Our system provides an overview-plus-detail display of the application's execution. A timeline view of pipeline performance data shows the overall utilization of the pipeline, indicating regions of poor instruction throughput. This information is displayed using multiple time scales, enabling the user to drill down from a high-level application overview to a focus region of hundreds of cycles. This region of interest is displayed in detail using an animated cycle-by-cycle view of the execution. This view shows how instructions are reordered and executed and how functional units are being utilized. Additional context views correlate instructions in this detailed view with the relevant source code for the application. This allows the user to discover the root cause of the poor pipeline utilization and make changes to the application to improve its performance