[petsc-dev] MatPinToCPU

[Mark Adams]

>
>
>   What are the symptoms of it not working? Does it appear to be still
> copying the matrices to the GPU? then running the functions on the GPU?
>
>
The object is dispatching the CUDA mat-vec etc.

  I suspect the pinning is incompletely done for CUDA (and MPIOpenCL)
> matrices.
>
>
Yes, git grep MatPinToCPU shows stuff for ViennaCL but not CUDA.

I guess I can add something like this below. Do we need to set the device
methods? They are already set when this method is set, right?


> We need the equivalent of
>
> static PetscErrorCode MatPinToCPU_SeqAIJViennaCL(Mat A,PetscBool flg)
> {
>   PetscFunctionBegin;
>   A->pinnedtocpu = flg;
>   if (flg) {
>     A->ops->mult           = MatMult_SeqAIJ;
>     A->ops->multadd        = MatMultAdd_SeqAIJ;
>     A->ops->assemblyend    = MatAssemblyEnd_SeqAIJ;
>     A->ops->duplicate      = MatDuplicate_SeqAIJ;
>   } else {
>     A->ops->mult           = MatMult_SeqAIJViennaCL;
>     A->ops->multadd        = MatMultAdd_SeqAIJViennaCL;
>     A->ops->assemblyend    = MatAssemblyEnd_SeqAIJViennaCL;
>     A->ops->destroy        = MatDestroy_SeqAIJViennaCL;
>     A->ops->duplicate      = MatDuplicate_SeqAIJViennaCL;
>   }
>   PetscFunctionReturn(0);
> }
>
> for MPIViennaCL and MPISeqAIJ Cusparse but it doesn't look like it has
> been written yet.
>
>
> >
> > It does not seem to work. It does not look like CUDA has an
> MatCreateVecs. Should I add one and copy this flag over?
>
>    We do need this function. But I don't see how it relates to pinning.
> When the matrix is pinned to the CPU we want it to create CPU vectors which
> I assume it does.
>
>
> >
> > Mark
>
>
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