If encountering issues with performance on GPFS, there are two parameters that you can tune:
- The "
bglockless" prefix: https://press3.mcs.anl.gov/romio/2013/08/05/bglockless/
With MPICH-3.1.1 and beyond this is no longer a problem: http://press3.mcs.anl.gov/romio/2014/06/05/new-romio-optimizations-for-blue-gene-q/
bg_nodes_pset" controls the number of aggregators. (See How to pass hints to MPI from HDF5.)