[gmx-developers] discussion of deprecation announcements in GROMACS 2021

[David van der Spoel]

On 2020-12-10 09:54, Mark Abraham wrote:
> Hi,
> 
> The developers announce functionality as deprecated each year. That 
> gives users a chance to learn what changes may happen in future, so they 
> can plan how to adapt.
> 
> I've proposed several things to deprecate at 
> https://gitlab.com/gromacs/gromacs/-/issues/3818 
> <https://gitlab.com/gromacs/gromacs/-/issues/3818> and want to encourage 
> people to consider those choices before I make an MR for the GROMACS 
> 2021 release notes.
> 
> Often things we announce as deprecated remain that way for months or 
> years before we actually remove it. That's fine.
> 
> The potentially controversial item is the proposed deprecation of OpenCL 
> support. We have active funded projects to implement support with SYCL 
> for Intel GPUs, and some as-yet undecided framework for AMD GPUs. When 
> those are in place, the usefulness of OpenCL as a portable approach for 
> GPU support in GROMACS has expired. We have not had the resources to 
> develop the current CUDA and OpenCL GPU code forks to the same extent, 
> and we are not going to be able to do that any better when SYCL and 
> perhaps HIP are also around. Continuing to support and test the OpenCL 
> functionality is work that we would need to do that costs us the 
> opportunity to further improve the ports we expect users to be using in 
> GROMACS 2022.
> 
> So, when we have made enough progress on the Intel and AMD fronts, we 
> want the freedom to remove the OpenCL port, so that there's less work 
> for us to do and more freedom to adapt our GPU portability layer in the 
> directions it needs to move. I hope that will happen some time during 
> the 2021 calendar year, but it won't be January :-).
> 
> Please feel free to discuss OpenCL here, and anything else at that 
> gitlab issue!
> 
> Mark
> 
The state of things with programming frameworks is rather miserable to 
say the least. From the link below I read that  HipSycl may cover both 
AMD and Nvidia GPUs. However, looking a bit closer, only the expensive 
AMD cards seem to be supported. We've been playing a bit with OpenMM 
recently that has extensive OpenCL support, and even on old laptops 
(Apple) that is a substantial improvement over using CPUs.

https://unix.stackexchange.com/questions/612736/sycl-and-opencl-for-amd-gpu

I guess there is no plan to abandon all the Nividia code in GROMACS for 
something else, right?

-- 
David van der Spoel, Ph.D.,
Professor of Computational Molecular Biophysics
Uppsala University.
http://virtualchemistry.org