Debugging with XMPI
From BCCD 3.0
XMPI is a graphical debugger that allows you to start MPI applications (compiled with LAM-MPI) and view message passing events during execution. Below is a very brief tutorial to get you started. More detailed documentation on XMPI can be found on the LAM-MPI page http://lam-mpi.org.
Contents |
Before You Begin...
Before you can start XMPI, you need to make sure you have compiled the MPI application correctly using LAM. LAM is a great MPI environment. Unfortunately it's not the default MPI environment on the BCCD. To set up LAM-MPI as the default MPI environment, follow the directions on Running LAM MPI, then compile the MPI program with the LAM environment using the steps found on Compiling and Running.
Starting XMPI
Starting up XMPI with the BCCD is easy. Just open a shell and type the command xmpi. The XMPI main window should pop up, as shown below:
Setting up an MPI Run
In the XMPI main window, click on the Application menu. From that menu, select Build&Run. It should bring up a window like the following:
In the top left corner of the above window, there is a field named Prog. In the above example, this field is already filled in with the MPI application ring (which can be found in ~/lam-mpi/examples/ring). In your screen, however, this field is most likely blank. Click the Browse button beside the field to browse through files to select the compiled MPI application you would like to debug.
The second field from the top is the Args field. You may fill in additional mpirun arguments in this field. In my example, I left this blank for simplicity.
The third field from the top is the Copy field. This is the field in which you can specify the number of copies you would like to run (annalogous to the MPICH -np option). Specify as many copies as you want!
In the middle of the window there is a Select Nodes section. Inside of it, you should see all the node you booted with lamboot, as well as two additional options (ALL NODES and LOCAL NODES). In my example I selected ALL NODES for simplicity.
For this example I left the rest of the options as they were, but feel free to play around with them!
Running the MPI Application
It's now time to make something happen! Click on the run button located in the bottom left corner of the Build&Run window.
