[gmx-developers] Double precision on GPU's

[Berk Hess]

Hi,

IIRC all Nvidia Tesla cards have always had double precision, at half 
the throughput of single precision. But there are very few cases where 
double precision is needed. Energy drift in single precision is never an 
issue, unless you really can not use a thermostat.

But having said that, making the GPU code, either CUDA or OpenCL work in 
double precision is probably not much effort. But making it work 
efficiently requires optimizing several algorithmic parameters and maybe 
changing the arrangement of some data in the different GPU memory levels.

Cheers,

Berk

On 7/22/19 10:10 PM, James wrote:
> Hi,
>
> My apologies if this question has been previously discussed. I just 
> joined the list and all I know is that from reading the docs and 
> release comments, writ ing code for double precision on GPU's is not a 
> priority.
>
> However, I believe all recent upper-end Nvidia cards have native 
> double precision (which was not true several generations ago). So, you 
> don't have to have a real "scientific computing" GPU to take advantage 
> of this -- most people probably already have the hardware. Still, I 
> understand that most people do not need/want to run double precision. 
> But, some do (and you have to if you are concerned with conservation 
> of energy -- the energy drift in single precision is substantial).
>
> So, I would like to ask what the level of effort to do this is 
> believed to be? Would it require a lot of new code, or would it be 
> porting the single precision code to double precision?
>
> Sincerely,
> James
>

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