Arm DDT

DDT is a tool for debugging C, C++ and Fortran parallel programs. It is available on the MACS and XCI systems as part of the Forge suite.

Useful links

A User Guide and Getting Started guide are available from https://developer.arm.com/tools-and-software/server-and-hpc/debug-and-profile/arm-forge/arm-ddt

Modules

To use DDT you will need to load the Forge module. On MACS the command is

module load allinea/forge

and on the XCI system the command is

module load tools/arm-forge

When you have loaded the module you can start the DDT graphical interface by running the command ddt &.

Example session

This example uses an interactive job running in the XCI arm-dev queue to debug a parallel program.

Start by compiling your program with a -g flag to retain extra debugging information. For example to compile a C program called myprog.c run

cc -g -o myprog myprog.c

which will produce an executable file called myprog.

Next start an interactive job by running the command

qsub -I -X -q arm-dev -l select=1 -l walltime=1:00:00

This starts an interactive job (-I) with X11 graphics forwarding (-X) using 1 compute node for up to 1 hour.

When the job starts load the Forge module

module load tools/arm-forge

We can now run ddt and tell it to start our program

ddt aprun -n 2 ./myprog

This example runs myprog with with 2 MPI processes. The ddt graphical interface will open and from here you can launch and debug your program.