[gmx-developers] GROMACS OpenCL on Gallium

[Szilárd Páll]

Vedran,

Unfortunately, don't think I will have enough time at least in the coming
1-2 weeks. I could help composing the kernel, but that's likely going to be
little effort and I am quite inexperienced with OpenCL, especially with the
API "glue" code needed to just have a small test kernel running.

I could pith in with putting together the kernel, but if the goal is to
have a simple test for global memory atomic addition on floats, perhaps the
best idea is to strip down an SDK example* like a float vector addition (or
reduction) and replace the regular global memory writes with
the atomicAdd_g_f() function implemented
in src/gromacs/mdlib/nbnxn_ocl/vectype_ops.clh.


* Both the AMD SDK and NVIDIA's ancient OpenCL SDK should have ready code,
but having checked briefly, a slight stripping down may be needed to remove
certain optimizations and avoid utility functions.

Cheers,
--
Szilárd

On Wed, Dec 9, 2015 at 10:30 AM, Vedran Miletić <rivanvx at gmail.com> wrote:

> 2015-12-04 18:13 GMT+01:00 Szilárd Páll <pall.szilard at gmail.com>:
> > Sounds good, is there anything on our side we can help with?
> >
> > Cheers,
> >
> > --
> > Szilárd
> >
>
> Szilard,
>
> actually, there is something that would be very useful, as I am
> struggling with testing my changes at the moment. It would be great to
> have minimal self-contained OpenCL example programs covering a
> spectrum of features we use. As a start, I could use a minimal atomic
> compare and swap example that would crash in the same way GROMACS does
> now.
>
> LLVM requires tests for all patches [1]. So I would certainly reuse these.
>
> Is this doable? I can try to make them myself, but you mentioned you
> are familiar with the code so I'm hoping you could make them quicker.
>
> Regards,
> Vedran
>
> [1] http://llvm.org/docs/DeveloperPolicy.html
>
> --
> Vedran Miletić
> http://vedranmileti.ch/
> --
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