Using the Totalview Debugger at NERSC

• Introduction
• Documentation
• Bassi
• Jacquard

Introduction

The Totalview Technologies totalview X Windows-based graphical debugger is available on Bassi and Jacquard. Typically a code is compiled for debugging by adding the -g compiler option when building a code. The code can then be run under totalview to step through the program, set break points, examine variables, etc., while viewing the source code. Totalview can also be used to examine core files and attach to running programs.

TotalView Documentation

Totalview Technologies provides a documentation web site. Additional instructions specific to NERSC platforms are described below.

Bassi

First load the totalview module:

% module load totalview

The first time you load the module an SSH key will be automatically created; this may take up to a minute or so. The key is used internally to launch totalview on batch nodes.

Serial codes

A serial code with an executable named program.x can be debugged with the following command.

% totalview ./program.x <-a optional program args>

Parallel programs

Parallel programs can be debugged interactively using the command line:

% totalview poe -a ./program.x  <optional program args> -nodes num_nodes -tasks num_tasks 

Once totalview starts, click on "Go" and totalview will tell you that "poe" is a parallel job and ask if you want to stop the parallel program. Answer "Yes" and you will be positioned at the beginning of your code. You can then set break points, etc. Refer to the Totalview Technologies documentation web site to learn how to use totalview.

Batch scripts

You can also run totalview in a batch script. Assuming you have used SSH to connect to Bassi and enabled X authentication forwarding (often the default, otherwise enabled with the -X flag on most UNIX systems), the totalview window will open on your display once the batch jobs starts. Obviously, this is not useful if you submit to a batch queue that has a long wait time (and unpredictable start time).

Licenses

The license for Bassi supports debugging parallel codes using up to 64 tasks.

Jacquard

Please see the Jacquard totalview page.

Licenses

Totalview on Jacquard supports debugging parallel programs using up to 32 tasks.