[Pw_forum] Memory issue in calculation with large unit-cell

[Elad Segev]

Dear QE users and developers,

I running a pw 'relax' calculation in a unit cell with 512 atoms of GeSe
with fcc symmetry and am running on a machine with 64 cores and 512GB RAM.
I encountered difficulties when tried to run on all cores (64) and the
memory usage was at 100% and started using the swap file heaviliy whille
most of the cores are not running with full CPU but only ~1% .

After trying to run on less cores on the macine, I ran on 16 cores and
found that the memory usage was at 502GB and with no use of the swap file,
all the cores are running at 100% CPU.

I'm runinng this job with 1 k-point so npool=1.
the MPI command is:
mpirun pw.x -np 16 -npool 1 -nband 1 -ntg 1
opmthreads=1

Is there a solution in which I can run on all cores?

Thanks in advance,

Elad Segev,
Ph.D. candidate
Ilse KAtz Institute of Nanoscale science and technology
Ben-Gurion University of the Negev, Israel
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