Histogram View

The Histogram View displays the trace events (counters data) distribution with respect to time. When performance analysis is running, this view is dynamically updated as the events are received.



The controls on the view are described in the table below.

Control Description
Selection Start Displays the start time of the current selection
Selection End Displays the end time of the current selection
Window Span Displays the current zoom window size in seconds

The controls can be used to modify their respective value. After validation, the other controls and views will be synchronized and updated accordingly. To modify both selection times simultaneously, press the link icon which disables the Selection End control input.

The large (full) histogram, at the bottom, shows the event distribution over the trace. It also has a smaller semi-transparent orange window, with a cross-hair, that shows the current zoom window.

The smaller (zoom) histogram, on top right, corresponds to the current zoom window, a sub-range of the event set.

The x-axis of each histogram corresponds to the event timestamps. The start time and end time of the histogram range is displayed. The y-axis shows the maximum number of events in the corresponding histogram bars.

The vertical blue line(s) show the current selection time (or range). If applicable, the region in the selection range will be shaded.

The table below lists the mouse actions that can be used to control the histogram.

Mouse Action Action Performed
Left-click Sets a selection time
Left-drag Sets a selection range
Shift+Left-click or drag Extend or shrink the selection range
Middle-click or CTRL+Left-click Centers the zoom window
Middle-drag or CTRL+left-drag Moves the zoom window
Right-drag Sets the zoom window
SHIFT+Right-click or drag Extend or shrink the zoom window
Mouse wheel up Zoom in
Mouse wheel dowm Zoom out

Hovering the mouse over an histogram bar pops up an information window that displays the start/end time of the corresponding bar, as well as the number of events it represents. If the mouse is over the selection range, the selection span in seconds is displayed.

The table below lists the keys and the action performed when they are used in the Histogram view.

Key Action Performed
Left Arrow Moves the current event to the previous non-empty bar.
Right Arrow Moves the current event to the next non-empty bar.
Home Sets the current time to the first non-empty bar.
End Sets the current time to the last non-empty histogram bar.
Plus (+) Zoom in
Minus (-) Zoom out