4.2. Qualitative Timeline

The Qualitative Timeline (Views Menu->Charts->Qualitative Timeline) shows event attributes like the data volume of messages as they occur over time. The value of this attribute is plotted along the y-axis while time is plotted along the x-axis. Select the required event type and attributes from the context menu. It helps detect patterns and irregular behavior such as extreme deviations or long-term changes in attribute values.

For the Poisson example, Figure 4-8 shows that the Qualitative Timeline gives a good impression of the pattern of function events Context Menu->Events to show. Zooming to a bunch of iterations again shows the staircase pattern observed above (see Section 1.5). Showing the transfer rates for messages results in a very instructive pattern for the given trace file.

A vertical line in the Qualitative Timeline either represents a single event (denoted as Single in the legend) or several events grouped together (denoted as Multi in the legend). Refer to Section 9.1 to find details on the merging of events.

Figure 4-8. Qualitative Timeline

4.2.1. Mouse Hover

When the mouse hovers over the Qualitative Timeline Chart, the value of the x-axis (representing time) for the given position is shown in the status bar. The status bar also shows details regarding the given position of the mouse. For example, when the Qualitative Timeline displays the Message attribute, the status bar shows how many messages are represented at that point. In case there is only one message, the sender and the receiver of the message are displayed as well. In the case where function events are displayed, mouse hovering indicates which Function/Group is present at the given position.

Figure 4-9. Status Bar when the mouse hovers over the Qualitative Timeline

4.2.2. Qualitative Timeline Settings

The settings dialog box of the Qualitative Timeline consists of a Display group with check boxes and a Vertical scaling combo box. Use the combo box to adjust the vertical scaling of the timeline.

Figure 4-10. The Qualitative Timeline settings dialog box

The Display Group specifies which scales to show and whether an own legend needs to be displayed for the timeline. By default, the vertical scale and the legend are shown.

Use the Vertical Scaling group to switch between the default Automatic Scaling and the Manual Scaling of the y-axis. To explicitly specify the maximum scale value, use Manual scaling. To visually compare two or more Charts in the same or distinct Views, specify the same maximum value for the charts.

4.2.3. Context Menu

The entry Context Menu->Events to show allows to choose the event type from Function Events, Messages and Collective Ops via a sub-menu.

The entry Context Menu->Attribute to show->xxx allows to choose the particular attribute value of the event from Duration, Transfer Rate or Data Volume via a sub-menu. Note that not all attributes are available for all event types.

4.2.4. Filtering and Tagging

Tagged items in the Qualitative Timeline are highlighted by coloring them red. For example, to tag all messages sent by P9, open the Tagging dialog box (Section 5.2) and go to the Messages tab.

Figure 4-11. Tagging in the Qualitative Timeline

Here, in the group Messages to be Tagged select the radio button titled Custom. Specify whatever needs to be tagged in the given field. Figure 4-11 shows that P9 is tagged, resulting in the timeline shown in Figure 4-12.

Figure 4-12. Qualitative Timeline with tagged messages

Similarly, to filter out all messages except those sent by P9, use the Filtering dialog box (Section 5.1) for details regarding the Filtering dialog box. It results in the following timeline:

Figure 4-13. Qualitative Timeline after filtering

Using tagging in the Qualitative Timeline is an efficient way to find specific events that occur infrequently. This is because it is guaranteed that a grouped multiple event is tagged if at least one of the singular events it represents matches the tagging filter expression.