Implementing a Scheduling Policy

The queuing portion of the schedule policy depends on which scheduling and resource management tool you are using. The mapping portions, however, are already modularized. There are a number of ways to override the default, including

• Substitute a different program for the beomap command and use mpirun to start jobs (which uses beomap).

• Create a shared library that defines the function get_beowulf_job_map() and use the environment variable LD_PRELOAD to force the pre-loading of this shared library.

• Create the shared library and replace the default /usr/liblibbeomap.so file.

These methods are in order of complexity. We can't actually highly recommend the first method as your mileage may vary. The second method is the most recommended followed by the third method of replacing the Scyld source code when you're happy that your scheduler is better.

It is highly recommended that you get the source code for the beomap package. It will give you a head start on writing your own mappers. For more information on developing your own mapper, see the Programmer's Guide.