Did you try the additional option -vec_type cuda with ex10.c ?
> On Aug 30, 2025, at 1:16 PM, LEDAC Pierre <[email protected]> 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, > > <pastedImage.png> > > > 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>
