Stepping (Part I)

You can use TotalView stepping commands to:

Execute one source line or machine instruction at a time; for example, Process > Step in the GUI and dstep in the CLI.

CLI: dstep

Run to a selected line, which acts like a temporary breakpoint; for example, Process > Run To.

CLI: duntil

Run until a function call returns; for example, Process > Out.

CLI: dout

In all cases, stepping commands operate on the Thread of Interest (TOI). In the GUI, the TOI is the selected thread in the current Process Window. In the CLI, the TOI is the thread that TotalView uses to determine the scope of the stepping ­operation.

On all platforms except SPARC Solaris, TotalView uses smart single-stepping to speed up stepping of one-line statements that contain loops and conditions, such as Fortran 90 array assignment statements. Smart stepping occurs when TotalView realizes that it doesn’t need to step through an instruction. For example, assume that you have the following statements:

integer iarray (1000,1000,1000)

iarray = 0

These two statements define one billion scalar assignments. If your computer steps every instruction, you will probably never get past this statement. Smart stepping means that TotalView single-steps through the assignment statement at a speed that is very close to your computer’s native speed.

Other topics in this section are:

“Understanding Group Widths”

“Understanding Process Width”

“Understanding Thread Width”

“Using Run To and duntil Commands”