[QE-users] parallelization of pw.x

[Michal Krompiec]

Hello,
I am trying to run a calculation on a 2D slab with a bit of adsorbate (119
atoms in total), and I would like to parallelize it as much as possible. I
am using a 3 3 1 Monkhorst-Pack grid (so I have 5 k-points).
I tried using -npool 5 -nt 4 using 20 MPI processes and 5 threads per
process but, as it seems, the speedup was just 3.7x:
   PWSCF        :   1d 4h27m CPU      7h43m WALL
What could have gone wrong, is there anything "obvious" I can do to
diagnose the problem? I am using QE 6.4rc, compiled with gcc and OpenMPI,
without ELPA.

Best regards,

Michal Krompiec

Merck KGaA and University of Southampton
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