TotalView Users Guide - CI Wiki

Setting a Breakpoint
introduced the types of groups contained with TotalView. That chapter
ignored what happens when you execute a TotalView command on a group.
For example, what does “stepping a group” actually mean? What happens
to processes and threads that aren’t in this group?
Associated with these three terms is a fourth term: arena. The arena is the
collection of processes, threads, and groups that are affected by a debugging
command. This collection is called an arena list.
In the GUI, the arena is most often set using the pulldown list in the toolbar.
You can set the arena using commands in the menubar. For example,
there are eight next commands. The difference between them is the arena;
that is, the difference between the next commands is the processes and
threads that are the target of what the next command runs.
When TotalView executes any action command, the arena decides the
scope of what can run. It doesn’t, however, determine what does run.
Depending on the command, TotalView determines the TOI, POI, or GOI,
and then executes the command’s action on that thread, process, or
group. For example, suppose TotalView steps the current control group:
� TotalView needs to know what the TOI is so that it can determine what
threads are in the lockstep group—TotalView only lets you step a lockstep
group.
� The lockstep group is part of a share group.
� This share group is also contained in a control group.
By knowing what the TOI is, the GUI also knows what the GOI is. This is
important because, while TotalView knows what it will step (the threads in
the lockstep group), it also knows what it will allow to run freely while it is
stepping these threads. In the CLI, the P/T set determines the TOI.
Setting a Breakpoint
You can set breakpoints in your program by selecting the boxed line numbers
in the Source Code pane of a Process window. A boxed line number
indicates that the line generates executable code. A icon masking a
line number indicates that a breakpoint is set on the line. Selecting the
icon clears the breakpoint.
When a program reaches a breakpoint, it stops. You can let the program
resume execution in any of the following ways:
� Use the single-step commands described in “Using Stepping Commands” on
page 239.
� Use the set program counter command to resume program execution at
a specific source line, machine instruction, or absolute hexadecimal
value. See “Setting the Program Counter” on page 248.
252 Chapter 13: Using Groups, Processes, and Threads