For a number of years SHARCNET has been providing a powerful GUI-based commercial debugger DDT (formerly Allinea; now owned by ARM) to its users. Recently it was transferred from legacy systems (orca and monk) to our new, national system Graham. (Please be aware that it is not available on Cedar because of the commercial licensing restrictions.) There are two DDT modules on Graham – ddt-cpu (debugging and profiling of serial, OpenMP, MPI, and hybrid MPI/OpenMP codes; up to 512 cpu cores across all Graham users), and ddt-gpu (debugging of CUDA, serial, OpenMP, MPI codes, and any combinations of the above; up to 8 GPUs across all Graham users). This webinar will first describe the basics of using DDT on Graham, and then will touch upon some more advanced topics (like debugging of hybrid codes) which we didn’t cover in the past webinars. Some prior knowledge of C/C++ or FORTRAN would be a plus.