Summer Scholarship Programme

	SSP 1998 Project Summary:

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Java Simulation of MPI Collective Communications

Student

Thomas Doel, University of Edinburgh

Supervisors

Elspeth Minty, EPCC

Bobby Davey, EPCC

As part of the MPI On-line course, a Java applet was produced which simulates the different blocking point to point communication modes in MPI. This type of simulation is extremely useful in teaching MPI as it allows students to understand the principles of point to point communications without having to worry about programming languages. This makes the programming exercises themselves much clearer to the students. The aim of this project is to build on this work by developing an equivalent Java applet for collective communications.

Each applet would consist of three processes each with an instruction panel to which the user can add instructions. The process and collective communication routine can be selected with different typeins/options for the different routines. The user interface from the point to point applet will be retained to minimise recoding.

The following is an outline of how some of the collective communications routines could be implemented. Examples of how the applets could look are included elsewhere in the proposal.

Barrier: The user would be required to add a barrier routine to the instruction list of each process. If any are missing then the applet will deadlock when run.
Broadcast: The user would provide the root process number and a value for the root process to broadcast. Any values in other processes would be over written. If any parameters are missing an error message is printed. Again the applet should deadlock if not all the processes call the broadcast routine.
Scatter: The user would be required to provide the root process, the amount of data to be sent to each process, the amount each process receives and values for the scatter array at the root process. Any information missing would result in an error message. Each process should include scatter on its instruction list with the same parameters.
Reduction: The user specifies the operation, root process, count and the data on each process. The result of the operation is displayed on the root process. Again missing information results in error messages and all processes should include the operation in their instruction lists.

The final report for this project is available here.

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