[QE-users] qe-6.4.1-qmcpack vs qe-6.7 Performace?

[Paolo Giannozzi]

A change in the distribution of plane waves for parallel FFT, aimed towards
increasing the scalability, may cause an increase of the execution time
under usual conditions (the default behavior has been reverted to the
previous one in the development version, though). Some other changes in the
default behavior may also affect the execution time. In particular, the
default for Davidson diagonalization is now to use a set of correction
vectors of minimal dimension (twice the number of bands) instead of the
previous one (four times). This spares some memory but may sometimes
increase the execution time. The default number of processors for parallel
linear algebra has also changed. Under some conditions, parallel linear
algebra may however be slower than the serial one. None of the above
justifies more than say a 25% difference or so. For a recent (this morning)
comparison: https://gitlab.com/QEF/q-e/-/issues/294

Paolo

On Tue, Feb 16, 2021 at 1:22 AM Stephen Zhang <lolzen at berkeley.edu> wrote:

> Hi Everyone,
>
> I'm currently using both the latest qe-6.7 and qe-6.4.1 qmcpack in my
> school computing HPC cluster and i've noticed that qe-6.4.1-qmcpack's
> version of pw.x is several times faster than qe-6.7 when performing scf and
> nscf runs. Both were configured for parallel runs using openmpi. Another
> difference is that while qe-6.4.1-qmcpack's pw.x is much faster during the
> run, it is also much slower when writing the data into prefix.save compared
> to qe-6.7, however this may be due to the fact that the 6.4.1-qmcpack's
> pw.x is configured to write the wavefunctions in the hdf5 format. The final
> difference I noticed was that qe-6.4.1-qmcpack's pw.x's filesize is much
> larger at 20mb compared to 4mb for qe-6.7's pw.x.
>
> Thanks,
> Stephen
>
>
> --
> *University of California, Berkeley*
> *Department of Letter and Sciences*
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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