The first view in the telemetry section is an overview that shows all available system and custom telemetries in compact rows on top of each other. With the row height slider you and adjust the density of the display and the filter at the top allows you to adjust the displayed telemetries by name. Clicking on the telemetry name in the overview will take you to a detailed telemetry view.
The system telemetries are:
Shows the maximum heap size and the amount of used and free space in it. This view can be displayed as a line graph or area graph.
When you profile a Java 1.5+ JVM, the drop down list at the top offers all available memory pools. Please see the article on tuning garbage collection for more information on heap memory pools. In addition, there are several memory pools for non-heap data structures. The drop down list shows all available memory pools in a tree-like structure, so you can display the sum of all heap pools (the default selection) or the sum of all non-heap pools in the graph.
When a view is shown as an area graph, the line which shows the total value is given by the upper bound of the filled area while the single contributions are shown as stacked area segments.
Horizontal and vertical grid lines of the VM telemetry views can be configured in the view settings dialog.