TotalView Users Guide - CI Wiki

Displaying Call Graphs
Figure 125: Tools > Call
Graph Dialog Box
a multi-process or multi-threaded program, numbers next to the arrows
indicate which threads have a routine on their call stack.
If you dive on a routine within the call graph, TotalView creates a group
called call_graph. This group contains all of the threads that have the routine
you dived on in its call stack. If you look at the Process Window’s Processes
tab, you’ll see that the call_graph set is selected in the scope pulldown.
In addition, the context of the Process Window changes to the first
thread in the set.
As you begin to understand your program, you will see that it has a rhythm
and a dynamic that is reflected in this diagram. As you examine and understand
this structure, you will sometimes see things that don’t look right—
which is a subjective response to how your program is operating. These
places are often where you want to begin looking for problems.
By diving on a routine that doesn’t look right, you’ll isolate the processes
into their own group so that you can find out what is occurring there. Every
time you dive on a routine, TotalView overwrites the group. If you want to
preserve the group, use the Groups > Custom Groups command to make a
copy of the group.
Looking at the call graph can also tell you where bottlenecks are occurring.
For example, if one routine is used by many other routines, and that routine
controls a shared resource, this thread might be negatively affecting
performance.
180 Chapter 9: Visualizing Programs and Data