On 04/12/2015 22:53, Maxim Skripnik wrote:
Hello,
I'm a bit confused by the parallelization scheme of QE. First of all,
I run calculations on a cluster with usually 1 to 8 nodes, each of
which has 16 cores. There is a very good scaling of pw.x e.g. for
structural relaxation jobs. I do not specify any particular
parallelization scheme as mentioned in the documentation, i.e. I start
the calculations with
mpirun -np 128 pw.x < job.pw
on 8 nodes, 16 cores each. According to the documentation ni=1, nk=1
and nt=1. So in which respect are the calculations parallelized by
default? Why do the calculations scale so well without specifying ni,
nk, nt, nd?
R and G parallelization is performed.
wavefunctions' planewaves, density planewaves and slices of real space
objects are distributed across 128 processors. A report of how this is
done is given at the beginning of the output.
Did you had a look to it ?
Second question is, whether one can speed up bands.x calculations. Up
to now I start these this way:
mpirun -np 64 bands.x < job.bands
on 4 nodes, 16 cores each. Does it make sense to define nb for
bands.x? If yes, what would be reasonable values?
expect no gain. band parallelization is not implemented in bands.
stefano
The systems of interest consist of typically ~50 atoms with periodic
boundaries.
Maxim Skripnik
Department of Physics
University of Konstanz
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