Stepping

TotalView's stepping commands allow you to:

• Execute one source line or machine instruction at a time.
   
• Run to a selected line, which acts like a temporary breakpoint.
   
• Run until a function call returns.

Single-step commands are on the Group, Process, and Thread menus, and operate at group, process, or thread width. This width affects which threads within a process and processes within a group TotalView allows to run while the single-stepping command is executing.

In all cases, stepping commands operate on the TOI, which is the selected thread in the current Process Window.

On all platforms except SPARC Solaris, TotalView uses smart single stepping to speed up stepping of one-line statements containing loops and conditions, such as Fortran 90 array assignment statements. Smart stepping occurs when TotalView realizes that it does not 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 cause one billion scalar assignments. If your machine steps every instruction, you will probably never get past this statement. Smart stepping means that TotalView will single step through the assignment statement at a speed that is very close to your machine's native speed.