[petsc-users] Cuda libraries and DMDA

[Matthew Knepley]

On Mon, Apr 9, 2018 at 6:12 PM, Manuel Valera <mvalera-w at sdsu.edu> wrote:

> Hello guys,
>
> I've made advances in my CUDA acceleration project, as you remember i have
> a CFD model in need of better execution times.
>
> So far i have been able to solve the pressure system in the GPU and the
> rest in serial, using PETSc only for this pressure solve, the library i got
> to work was ViennaCL. First question, do i still have to switch
> installations to use either CUDA library? this was a suggestion before, so
> in order to use CUSP instead of ViennaCL, for example, i currently have to
> change installations, is this still the case?
>

I am not sure what that means exactly. However, you can build a PETSc with
CUDA and ViennaCL support. The type of Vec/Mat is selected at runtime.


> Now, i started working in a fully parallelized version of the model, which
> uses the DMs and DMDAs to distribute the arrays, if i try the same flags as
> before i get an error saying "Currently only handles ViennaCL matrices"
> when trying to solve for pressure, i get this is a feature still not
> implemented? what options do i have to solve pressure, or assign a DMDA
> array update to be done specifically in a GPU device?
>

If we can't see the error, we are just guessing. Please send the entire
error message.

Note, we only do linear algebra on the GPU, so none of the
FormFunction/FormJacobian stuff for DMDA would be on the GPU.


> I was thinking of using the VecScatterCreateToZero for a regular vector,
>

Why do you want a serial vector?


> but then i would have to create a vector and copy the DMDAVec into it,
>

I do not understand what it means to copy the DM into the Vec.

  Thanks,

     Matt


> is this accomplished with DMDAVecGetArrayReadF90 and then just copy? do
> you think this will generate too much overhead?
>
> Thanks so much for your input,
>
> Manuel
>



-- 
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.caam.rice.edu/~mk51/>
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