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<p>Dear Paolo,</p>
<p>Thank you very much for your response, that was indeed what was causing the error.</p>
<p>During my investigation, I noticed that an error check in PHonon/PH/solve_linter.f90 should have been firing, but wasn't; I've submitted a fix on GitLab <a href="https://gitlab.com/QEF/q-e/-/merge_requests/941/diffs">https://gitlab.com/QEF/q-e/-/merge_requests/941/diffs</a>.</p>
<p>Best,</p>
<p>Michael</p>
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<p id="reply-intro">On 2020-05-19 17:44, Paolo Giannozzi wrote:</p>
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<div>If I understand correctly, you are parallelizing over k points with 32 processors, but you have just 20 k points. As a consequence, in all loops over k-points, 12 processors will do nothing. While I am quite sure that such a wasteful parallelization works anyway for the self-consistent code, I am not equally sure it will for the phonon code. It isn't presumably difficult to fix it, but I would move to a more sensible parallelization. For 20 k points and 32 processors, I would try 4 pools of 8 processors (mpirun -np 32</div>
<div> ph.x -nk 4 ...)</div>
<div>Paolo</div>
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<div class="v1gmail_attr" dir="ltr">On Tue, May 19, 2020 at 2:12 PM M.J. Hutcheon <<a href="mailto:mjh261@cam.ac.uk" rel="noreferrer">mjh261@cam.ac.uk</a>> wrote:</div>
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<p>Dear QE users/developers,</p>
<p>Following from the previous request, I've changed to a newer MPI library which gives a little more error information, specifically it does now crash with the following message:</p>
<p>An error occurred in MPI_Allreduce<br />eported by process [1564540929,0]<br />on communicator MPI COMMUNICATOR 6 SPLIT FROM 3<br />MPI_ERR_TRUNCATE: message truncated<br />MPI_ERRORS_ARE_FATAL (processes in this communicator will now abort, and potentially your MPI job)</p>
<p>It appears that this is thrown at the end of a self-consistent DFPT calculation (see the attached output file - it appears the final iteration has converged). I'm using the development version of QE, so I suspect that the error arises from somewhere inside <a href="https://gitlab.com/QEF/q-e/-/blob/develop/PHonon/PH/solve_linter.f90" target="_blank" rel="noopener noreferrer">https://gitlab.com/QEF/q-e/-/blob/develop/PHonon/PH/solve_linter.f90</a>.</p>
<p>I don't really know how to debug/workaround this further, any ideas/suggestions would be most welcome.</p>
<p>Best,</p>
<p>Michael Hutcheon</p>
<p>TCM group, University of Cambridge</p>
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<p id="v1gmail-m_6701944341264809987reply-intro">On 2020-05-12 13:29, M.J. Hutcheon wrote:</p>
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<p>Dear QE users/developers,</p>
<p>I am running an electron-phonon coupling calculation at the gamma point for a large unit cell Calcium-Hydride (Output file attached). The calculation appears to get stuck during the DFPT stage. It does not crash, or produce any error files/output of any sort, or run out of walltime, but the calculation does not progress either. I have tried different parameter sets (k-point grids + cutoffs), which changes the representation where the calculation gets stuck, but it still gets stuck. I don't really know what to try next, short of compiling QE in debug mode and running under a debugger to see where it gets stuck. Any ideas before I head down this laborious route?</p>
<p>Many thanks,</p>
<p>Michael Hutcheon</p>
<p>TCM group, University of Cambridge</p>
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_______________________________________________<br />Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu/quantum-espresso" target="_blank" rel="noopener noreferrer">www.max-centre.eu/quantum-espresso</a>)<br />users mailing list <a href="mailto:users@lists.quantum-espresso.org" rel="noreferrer">users@lists.quantum-espresso.org</a><br /><a href="https://lists.quantum-espresso.org/mailman/listinfo/users" target="_blank" rel="noopener noreferrer">https://lists.quantum-espresso.org/mailman/listinfo/users</a></blockquote>
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<div>Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,<br />Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br />Phone +39-0432-558216, fax +39-0432-558222<br /><br /></div>
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<div class="pre" style="margin: 0; padding: 0; font-family: monospace">_______________________________________________<br />Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu/quantum-espresso" target="_blank" rel="noopener noreferrer">www.max-centre.eu/quantum-espresso</a>)<br />users mailing list <a href="mailto:users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a><br /><a href="https://lists.quantum-espresso.org/mailman/listinfo/users" target="_blank" rel="noopener noreferrer">https://lists.quantum-espresso.org/mailman/listinfo/users</a></div>
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