[QE-users] Questions regarding parallelism and memory usage of ph.x calculations

[Paolo Giannozzi]

It might be a problem of memory. The parallelization over plane waves
distributes most memory, unlike parallelization over k-points. If a smaller
version of the run works, this is the likely explanation. If instead the
problem persists, the problem might be in k-point parallelization (in which
case we need an example an information on the phonon version you are using)

Paolo

On Tue, Jun 11, 2019 at 11:53 AM Laurens Siemons <laurenssiemons at hotmail.be>
wrote:

> Dear QE-users,
>
>
> I tried to run a ph.x calculation on 100 processors of a system with 5
> unique k-points so I used the -nk 5 command to divide the calculation into
> 5 pools of 20 processors. After printing which representations will be
> calculated in this run, the output returns the following error message:
>
>
> ...
>
>      Representation   469      1 modes -A  To be done
>
>      Representation   470      1 modes -A  To be done
>
>      Representation   471      1 modes -A  To be done
>
>      Compute atoms:   149,  150,  151,  152,  153,  154,  155,  156,
>   157,
>
>
>
>
> ===================================================================================
> =   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
> =   PID 16398 RUNNING AT r3c4cn08.hopper
> =   EXIT CODE: 9
> =   CLEANING UP REMAINING PROCESSES
> =   YOU CAN IGNORE THE BELOW CLEANUP MESSAGES
>
> ===================================================================================
>    Intel(R) MPI Library troubleshooting guide:
>       https://software.intel.com/node/561764
>
> ===================================================================================
>
> However, if I perform the same calculation without parallellization over
> the unique k-points, the calculation achieves convergence without a
> problem.
>
> Parallellization over the 5 unique k-points works without a problem in the
> corresponding pw.x calculation. Any idea what can cause this issue?
>
>
> Except for this, I had an additional question regarding the memory usage
> of a ph.x calculation. While running such calculations, the memory usage
> goes up until approximately 200G. I'm performing calculations on a
> cluster and the amount of memory I can use is limited. Are there
> general tricks/methods to reduce the memory usage of ph.x calculations?
>
>
> Thanks in advance,
>
> Laurens Siemons
>
> PhD Student, UAntwerp
> _______________________________________________
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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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