How to Initiate the Portland Group pgdbg Debugger

On the Katana, you can use the Portland Group's pgdbg multi-threaded debugger to debug OpenMP FORTRAN or C codes. Due to hardware constraints, debugging MPI code using pgdbg is not available on the Katana.

Debugging OpenMP codes with pgdbg

To start pgdbg, follow the step-by-step procedures shown below:

• Step 1. Compile the program using the appropriate PGI compiler with -g to turn on debugging. Remove all optimization flags, if used.
• Step 2. At the system prompt, define the number of threads (1 to 4) for use with debugger.

  
  katana:~ % setenv OMP_NUM_THREADS 2
  

• Step 3. Launch the pgdbg in the directory where both the source code and executable reside.
  

  
  katana:~ % pgdbg a.out
  

  • By default, the above launches the GUI-based pgdbg.
    You will need an X-server based windowing software for this to work. At BU, if you access Katana from a Windows-based PC, you can download x-win32 for free.
  • If you prefer command-line instead of GUI debugging environment, add -text.
    You don't need X-server for this mode.

    
    katana:~ % pgdbg -test a.out
    

  • Adding the -dbx flag enables you to issue dbx commands within the debugger environment.
    you need X-server unless you also use the -text option.
• Step 4. Set breakpoint(s). Then click on the "run" button.
  
  
  • For more details on pgdbg usage, please refers to the PGI Tools Guide (pdf).

Debugging MPI codes with pgdbg