[petsc-users] [SPAM?] Re: Requesting multi-GPUs

[Karl Rupp]

Hi Manuel,

we do not handle more than one GPU per MPI process. If we did, we would 
have to duplicate all the existing MPI communication pattern for the 
multiple GPUs on a single process. This is a significant maintenance 
burden, yet it would not provide any significant performance benefits.

Best regards,
Karli



On 09/12/2018 11:31 PM, Manuel Valera wrote:
> Ok then, how can i try getting more than one GPU with the same number of 
> MPI processes?
> 
> Thanks,
> 
> On Wed, Sep 12, 2018 at 2:20 PM, Matthew Knepley <knepley at gmail.com 
> <mailto:knepley at gmail.com>> wrote:
> 
>     On Wed, Sep 12, 2018 at 5:13 PM Manuel Valera <mvalera-w at sdsu.edu
>     <mailto:mvalera-w at sdsu.edu>> wrote:
> 
>         Hello guys,
> 
>         I am working in a multi-gpu cluster and i want to request 2 or
>         more GPUs, how can i do that from PETSc? evidently mpirun -n #
>         is for requesting processors, but what if i want to use one mpi
>         processor but several GPUs instead?
> 
> 
>     We do not do that. You would run the same number of MPI processes as
>     GPUs. Note that
>     you can have more than 1 MPI process on a processor.
> 
>        Matt
> 
>         Also, i understand the GPU handles the linear system solver, but
>         what about the data management? can i do DMs for other than the
>         linear solver using the GPUs
>         ?
> 
>         Thanks once more,
> 
> 
> 
> 
>     -- 
>     What most experimenters take for granted before they begin their
>     experiments is infinitely more interesting than any results to which
>     their experiments lead.
>     -- Norbert Wiener
> 
>     https://www.cse.buffalo.edu/~knepley/
>     <http://www.cse.buffalo.edu/%7Eknepley/>
> 
>