Re: [QE-users] mutlicore usage for GPU.

[Paolo Giannozzi]

On 26/04/2024 23:00, Bhargab Kakati wrote:

while using more 
than one core (mpirun -np 8) the calculation becomes very slow but it is 
way faster when I do "mpirun -np 1". Is there a reason for that?


of course there is a reason, and you mention it in the following line:


I have only 1 GPU


You should run one MPI process per GPU. If you have 1 GPU, you don't 
even need MPI. You may find OpenMP useful if you have available CPU 
cores, but don't expect any serious speedup from OpenMP


Paolo
--
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216
AVAILABLE POSITION: 
https://physicslab.uniud.it/persone/paolo-giannozzi/prin2022

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[QE-users] mutlicore usage for GPU.

[Bhargab Kakati]

Hello experts,I have compiled QE for GPU (MPI + OpenMP). I've that while using more than one core (mpirun -np 8) the calculation becomes very slow but it is way more faster when I do "mpirun -np 1". Is there a reason for that?I have only 1 GPU and i have added "export OMP_NUM_THREADS=1" in the bashrcthank you.___
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
___
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list users@lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users