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Default differences

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How does the default behaviour of HPCx differ from other IBM eServer 575 clusters?

Environment Variables

The following environment variables have been reset. whereas the IBM defaults are

LPARs

We define our LPARs (Logical PARtions) to be the same as two MCMs (Multi-Chip Modules), which are tightly coupled, so that we may use all the switch channels to allow maximum communication through-put. For HPCx, each LPAR has 16 processors.

LoadLeveler

If your job is a parallel job, then you must specify job_type=parallel and node_usage=not_shared

If your job is a serial job, then you must specify job_type=serial and node_usage=shared

If your job is an interactive job, then you must specify job_type=parallel and node_usage=shared

LoadLeveler imposes a maximum memory per task to be 14.4GB/(number-of-processes), where number-of-processes is the number_of_tasks in a purely MPI job, or number_of_tasks*OMP_NUM_THREADS, in a mixed-mode code.

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