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

[Justin Lemkul]

On 12/30/14 1:38 PM, Carlos Navarro Retamal wrote:
> 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?

In this case, both GPU are probably fighting for CPU resources (note how the CPU 
force evaluation is the limiting factor).  You'll need to set -pin and 
-pinoffset suitably, IIRC.  See discussion at

http://www.gromacs.org/Documentation/Acceleration_and_parallelization

-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 | (410) 706-7441
http://mackerell.umaryland.edu/~jalemkul

==================================================