[QE-users] QE Performance on cluster and AMD

[Paolo Giannozzi]

On Sat, Apr 25, 2020 at 1:34 AM Baer, Bradly <bradly.b.baer at vanderbilt.edu>
wrote:


> My submitted jobs for phonon calculations keep being canceled because QE
> is writing large files to the networked filesystem which is both very slow
> and under a fairly tight quota.
>

don't you have anything else to use for scratch files? in the worst-case
scenario, a local /tmp or /scratch file system, even if not visible to all
processors, may do the job (with some caveats)

  Files in the _ph0  directory, and appear to be creating one file per
> processor that I request for my job. Is there some way to have QE load
> these files in to RAM instead
>

there is some way, but it requires some work and some understanding of how
the "buffer" machinery used in the self-consistent code works. If you feel
brave enough to work with the latest development version and to perform
some tests, I can explain what to do.

A second question: has anyone had success in using QE on AMD Ryzen
> processors?  I have a Ryzen system that is struggling to match the
> performance of an Intel system that is several years older. Both are
> running QE6.5 on Ubuntu.  From pw.x output, cegterg is 10x slower and
> cdiaghg is 100x slower on the AMD machine.   I had hoped that going from 4
> cores to 16 cores would make it faster, not slower!
>

100x means that something VERY wrong is happening. Are you sure there isn't
some conflict between MPI and multithreading? Please also see the following
message, that contains an important piece of information:
https://www.mail-archive.com/users@lists.quantum-espresso.org/msg37148.html

Paolo


>
> Thanks,
> Bradly Baer
> --------------------------------------------------------
> Bradly Baer
> Graduate Research Assistant, Walker Lab
> Interdisciplinary Materials Science
> Vanderbilt University
>
>
> _________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
> users mailing list users at lists.quantum-espresso.org
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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