You are right, in the sense that now the code just writes
"suboptimal parallelization: some nodes have no k-points"
I'm quite sure I remember the code stopping because it was run with more
pools than k-points, was this changed recently, Paolo?
On 5/20/20 10:34 AM, M.J. Hutcheon wrote:
Dear Lorenzo,
I'm quite sure that the pw code stops if you try to run with more
pools than k-points !
This doesn't seem to be the case? I ran a vc-relax and an scf (attached
output) with these (terrible) parallelism settings, and they ran just fine.
Best,
Michael
On 2020-05-20 09:25, Lorenzo Paulatto wrote:
While I am quite sure that such a wasteful parallelization works
anyway for the self-consistent code,
I'm quite sure that the pw code stops if you try to run with more
pools than k-points !
I am not equally sure it will for the phonon code.
If the ph code does not stop in this case, I'm confident it will not
work properly!
cheers
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
ph.x -nk 4 ...)
Paolo
On Tue, May 19, 2020 at 2:12 PM M.J. Hutcheon <mjh...@cam.ac.uk
<mailto:mjh...@cam.ac.uk> <mailto:mjh...@cam.ac.uk
<mailto:mjh...@cam.ac.uk>>> wrote:
Dear QE users/developers,
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:
An error occurred in MPI_Allreduce
eported by process [1564540929,0]
on communicator MPI COMMUNICATOR 6 SPLIT FROM 3
MPI_ERR_TRUNCATE: message truncated
MPI_ERRORS_ARE_FATAL (processes in this communicator will now abort,
and potentially your MPI job)
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
https://gitlab.com/QEF/q-e/-/blob/develop/PHonon/PH/solve_linter.f90.
I don't really know how to debug/workaround this further, any
ideas/suggestions would be most welcome.
Best,
Michael Hutcheon
TCM group, University of Cambridge
On 2020-05-12 13:29, M.J. Hutcheon wrote:
Dear QE users/developers,
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?
Many thanks,
Michael Hutcheon
TCM group, University of Cambridge
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