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.

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:

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.