Dear Quantum Espresso Developers and Users,
I'm running a phonon calculation parallelizing over the representations/q vectors. For my cluster, there are 24 cores per node. I want to use as many nodes as possible to speed up the calculation. I set the number of parallelizations to be the number of nodes, > mpirun -np NUMBER_OF_NODESx24 ph.x -nimage NUMBER_OF_NODES > If I only use 4 nodes (4 images), 8 nodes ( 8 images), the calculation will be finished successfully. However, more than 8 nodes, say 16 or 32 nodes, are used, each time running the calculation, such error will be given, > Not diagonalizing because representation xx is not done > Btw, I want to reduce I/O overhead by discarding `wf_collect` option, but the following way doesn't work (the number of processors and pools for scf calculation is the same to that in phonon calculation) mpirun -np NUMBER_OF_NODESx24 pw.x > ph.x complains, > Error in routine phq_readin (1):pw.x run with a different number of > processors. > Use wf_collect=.true. > The beginning output of pw.x, > Parallel version (MPI), running on 96 processors > R & G space division: proc/nbgrp/npool/nimage = 96 > Waiting for input... > Reading input from standard input > and the beginning output of ph.x, > Parallel version (MPI), running on 96 processors > path-images division: nimage = 4 > R & G space division: proc/nbgrp/npool/nimage = 24 > Do I miss something? I know it's inefficient to let pw.x use so many processors, but it seems to be one requirement to let ph.x and pw.x have the same number of processors. Thank you! -- *Best regards,* *Coiby*
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