User Guide

Intel® VTune™ Profiler User Guide

ID 766319
Date 12/16/2022

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Document Table of Contents

Window: Top-down Tree

Use the Top-down Tree window to explore the call sequence flow of the application and analyze the time spent in each program unit and on its callees.

To access this pane: Run a performance analysis type collecting stacks and click the Top-down Tree tab when the collection result opens.

Function Stack

The Function Stack column represents call sequences (stacks) detected during collection phase starting from the application root (usually, the main() function). The time value for a row is equal to the sum of all the nested items from that row. Use this data to see the impact of program units together with their callees. This type of investigation is known as a top-down analysis.

In this example above, the hotspot thread_video function has three callees, where rt_renderscene is the first candidate for optimization.

The call stacks are always available for the results of the user-mode sampling and tracing collection. They are also available for the results of the hardware event-based sampling collection, if you enabled the Collect stacks option during the analysis configuration. Otherwise, the Function Stack column for the event-based sampling results shows a flat list of the functions.

<Performance metrics>

Each data column in the Top-Down Tree grid corresponds to a performance metric. The list of performance metrics varies with the analysis type and selected viewpoint. In the Top-down Tree window, the Intel® VTune™ Profiler provides two types of metrics:

  • Self metrics show performance data collected within particular procedures and functions.

  • Total metrics show performance data collected within functions AND children (callees).

By default, all program units are sorted in a descending order by the metric values in the first column (for example, CPU Time: Total) providing the most performance-critical program units first. You may click a column header to re-sort the table by the required metric.


Mouse over a column header to see a metric description.