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<div class="moz-cite-prefix">On 04/12/2015 22:53, Maxim Skripnik
wrote:<br>
</div>
<blockquote
cite="mid:bbc1c3d2d4083244.56620b59@limbe.rz.uni-konstanz.de"
type="cite">Hello,<br>
<br>
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<br>
mpirun -np 128 pw.x < job.pw<br>
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?<br>
</blockquote>
R and G parallelization is performed. <br>
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. <br>
Did you had a look to it ?<br>
<br>
<blockquote
cite="mid:bbc1c3d2d4083244.56620b59@limbe.rz.uni-konstanz.de"
type="cite">Second question is, whether one can speed up bands.x
calculations. Up to now I start these this way:<br>
mpirun -np 64 bands.x < job.bands<br>
on 4 nodes, 16 cores each. Does it make sense to define nb for
bands.x? If yes, what would be reasonable values?<br>
</blockquote>
expect no gain. band parallelization is not implemented in bands.<br>
<br>
stefano<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<blockquote
cite="mid:bbc1c3d2d4083244.56620b59@limbe.rz.uni-konstanz.de"
type="cite">The systems of interest consist of typically ~50 atoms
with periodic boundaries.<br>
<br>
Maxim Skripnik<br>
Department of Physics<br>
University of Konstanz
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