[petsc-dev] Backend independent VecGetArray for GPUs

[Matthew Knepley]

On Fri, Oct 17, 2014 at 10:45 AM, Lisandro Dalcin <dalcinl at gmail.com> wrote:

> On 17 October 2014 17:54, Dominic Meiser <dmeiser at txcorp.com> wrote:
> > Hi Ashwin,
> >
> > Are you suggesting that `VecGetGPUArray*`  be added to the `Vec`
> interface?
> > That might be problematic because these methods only makes sense for GPU
> > vectors. The interface of `Vec` would then be tied to the PETSc
> > configuration.
> >
>
> These methods could be always available simply generate an error for
> non-GPU vector types.
>
> > An alternative might be to compose the various `VecCUSPGetArray` and
> related
> > methods with `Vec` objects. You could then query these methods and use
> them
> > if available (and handle absence of the methods if needed, e.g. throw an
> > exception). This would be easy to add.
> >
>
> Yes, however note that what we really need is a backend-independent
> way to get the RAW pointer to the GPU buffers. Right now we have calls
> to get the CUSP or ViennaCL array, to handle them you need C++ and
> depend on CUDA/OpenCL at compile-time.
>

Why would we want this? The packages themselves (CUDA/ViennaCL) only expose
memory using these specific types. What use is it to wrap these up in a
void * if you
just have to caste back down to use them. Isn't it better to maintain
type-specific, and
type safe, interfaces for this stuff?

  Matt


>
> --
> Lisandro Dalcin
> ============
> Research Scientist
> Computer, Electrical and Mathematical Sciences & Engineering (CEMSE)
> Numerical Porous Media Center (NumPor)
> King Abdullah University of Science and Technology (KAUST)
> http://numpor.kaust.edu.sa/
>
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>
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>



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