Starting DDT on Eddie
DDT is a graphical debugger modified from gdb for debugging parallel codes. It is able to debug various MPI codes across different nodes. DDT has been integrated with the batch queue system (SGE) on eddie - it will submit jobs for users and run interactively in SGE.
The following steps show how to use DDT on eddie:
1. Login with X11 authentication
ssh -X eddie.ecdf.ed.ac.uk
2. Add MPI and DDT modules to your environment
module add openmpi/gcc module add ddt/64
3. Compile your MPI code with debugging option
mpicc -g -o foo foo.c
a good example file: /usr/local/Cluster-Apps/ddt/1.10/examples/rotating.c
4. Start the DDT GUI
ddt &
6. If everything goes well, you should see the DDT GUI together with a Session Control Panel. Click the button "..." to browse your work directory and select the application to be debugged. Tell DDT the number of processes your application will need (must be less than 64). Then click "Submit" button to submit your job to batch system. Your job will begin to run under debug mode once there are resources available for you.
New: use different MPI in DDT
1. open DDT GUI
2. Click Change on session control panel. You will see a DDT Options panel
3. Select proper MPI from MPI Implementation pull down list
4. Browns and select a template file for your MPI. We have provided sample template file at /usr/local/Cluster-Apps/ddt/1.10/config/template.*.qtf, copy these files to your work dir and change them for your job
Warning: DDT has been configured and tested by ECDF System Team. Changing DDT options may cause problems, so don't make any changes unless you know what you are doing. If all else fails, you can delete your ~/.ddt/ folder, log out of Eddie and log back in again. If you need a different MPI environment in DDT to those provided, please contact Science Support.