[petsc-users] [MPI][GPU]

[LEDAC Pierre]

Yes, but was surprised it was not used, so I removed it (same for -vec_type mpicuda)


mpirun -np 2 ./ex10 2 -f Matrix_3133717_rows_1_cpus.petsc -ksp_view -log_view -ksp_monitor -ksp_type cg -pc_type hypre -pc_hypre_type boomeramg -pc_hypre_boomeramg_strong_threshold 0.7 -mat_type aijcusparse -vec_type cuda

...

WARNING! There are options you set that were not used!
WARNING! could be spelling mistake, etc!
There is one unused database option. It is:
Option left: name:-vec_type value: cuda source: command lin


Pierre LEDAC
Commissariat à l’énergie atomique et aux énergies alternatives
Centre de SACLAY
DES/ISAS/DM2S/SGLS/LCAN
Bâtiment 451 – point courrier n°41
F-91191 Gif-sur-Yvette
+33 1 69 08 04 03
+33 6 83 42 05 79
________________________________
De : Barry Smith <bsmith at petsc.dev>
Envoyé : samedi 30 août 2025 21:47:07
À : LEDAC Pierre
Cc : petsc-users at mcs.anl.gov
Objet : Re: [petsc-users] [MPI][GPU]


Did you try the additional option -vec_type cuda with ex10.c ?



On Aug 30, 2025, at 1:16 PM, LEDAC Pierre <Pierre.LEDAC at cea.fr> wrote:

Hello,

My code is built with PETSc 3.23+OpenMPI 4.1.6 (Cuda support enabled) and profling indicates that MPI communications are done between GPUs in all the code except PETSc part where D2H transfers occur.

I reproduced the PETSc issue with the example under src/ksp/ksp/tutorials/ex10 on 2 MPI ranks. See output in ex10.log

Also below the Nsys system profiling on ex10 with D2H and H2D copies before/after MPI calls.

Thanks for your help,

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Pierre LEDAC
Commissariat à l’énergie atomique et aux énergies alternatives
Centre de SACLAY
DES/ISAS/DM2S/SGLS/LCAN
Bâtiment 451 – point courrier n°41
F-91191 Gif-sur-Yvette
+33 1 69 08 04 03
+33 6 83 42 05 79
<ex10.log>

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