[gmx-users] low performance 2 GTX 980+ Intel CPU Core i7-5930K 3.5 GHz (2011-3)

[Carlos Navarro Retamal]

Dear Justin,
Thanks a lot for your reply.

> You can use the multiple cards to run
> concurrent simulations on each (provided cooling is adequate to do this).



I tried that. I launched 2 simulation at the same time, but on each i got the next warning at the end:

> Force evaluation time GPU/CPU: 3.177 ms/5.804 ms = 0.547
> For optimal performance this ratio should be close to 1!
>  
>  
> NOTE: The GPU has >25% less load than the CPU. This imbalance cause
>       performance loss.

and i got really low performance ( ~ 17ns/day each)  
using the following commands:

> mdrun -deffnm test1 -gpu_id 0 -v
> mdrun -deffnm test2 -gpu_id 1 -v



Is there a better way to perform multiple md simulations at the same time?
Best regards,
Carlos
--  
Carlos Navarro Retamal
Bioinformatic engineer
Ph.D(c) in Applied Science, Universidad de Talca, Chile
Center of Bioinformatics and Molecular Simulations (CBSM)
Universidad de Talca
2 Norte 685, Casilla 721, Talca - Chile   
Teléfono: 56-71-201 798,  
Fax: 56-71-201 561
Email: carlos.navarro87 at gmail.com or cnavarro at utalca.cl


On Tuesday, December 30, 2014 at 3:30 PM, Justin Lemkul wrote:

>  
>  
> On 12/30/14 1:29 PM, Carlos Navarro Retamal wrote:
> > Dear gromacs users,
> > I just found that i installed a old version of CUDA https://developer.nvidia.com/cuda-downloads
> > Instead of a new one for my graphic cards.
> > https://developer.nvidia.com/cuda-downloads-geforce-gtx9xx
> > Do you think that this can be the problem?
> >  
> > In any case i’ll install the new tool kit and compile gromacs again.
>  
> The simplest answer to your problem is that a system of 90k atoms doesn't scale  
> well beyond 1 GPU on your hardware. People report similar things frequently.  
> There is a need for balance between CPU:GPU workload and communication between  
> the GPU. Probably, given your hardware, 90k is not such a large system that it  
> is likely to benefit from multiple GPU. You can use the multiple cards to run  
> concurrent simulations on each (provided cooling is adequate to do this).
>  
> -Justin
>  
> --  
> ==================================================
>  
> Justin A. Lemkul, Ph.D.
> Ruth L. Kirschstein NRSA Postdoctoral Fellow
>  
> Department of Pharmaceutical Sciences
> School of Pharmacy
> Health Sciences Facility II, Room 629
> University of Maryland, Baltimore
> 20 Penn St.
> Baltimore, MD 21201
>  
> jalemkul at outerbanks.umaryland.edu (mailto:jalemkul at outerbanks.umaryland.edu) | (410) 706-7441
> http://mackerell.umaryland.edu/~jalemkul
>  
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