[gmx-users] why two GTX780ti is slower?

[Mark Abraham]

Hi,

Nobody can tell unless you upload .log files and mdrun command lines
somewhere

Mark


On Wed, May 14, 2014 at 7:03 AM, Albert <mailmd2011 at gmail.com> wrote:

> Hello:
>
> I've compiled Gromacs in a GPU machine with two GTX780Ti with following
> command:
>
> env CC=icc F77=ifort CXX=icpc CMAKE_PREFIX_PATH=/soft/intel/
> mkl/include/fftw:/soft/intel/impi/4.1.3.049/intel64:/soft/
> intel/mkl/lib/intel64 <http://4.1.3.049/intel64:/
> soft/intel/mkl/lib/intel64> cmake .. -DBUILD_SHARED_LIB=OFF
> -DBUILD_TESTING=OFF -DCMAKE_INSTALL_PREFIX=/soft/gromacs-5.0rc1
> -DGMX_MPI=ON -DGMX_GPU=ON -DCUDA_TOOLKIT_ROOT_DIR=/usr/local/cuda
>
>
> I've got 40ns/day for a 65,000 atoms membrane system under CHARMM36 FF
> when one GPU is used, but it is only 27ns/day if I used two GPUs. In
> another machine with two GTX690, I used ICC+openmpi instead of ICC+intel
> MPI. The same system, I obtained 40ns/day for one GPU, and 60ns/day for two
> GPU.
>
> I am just wondering, why it is even slower with two GTX780Ti for my
> system, which doesn't happen to GTX690?
>
> thx a lot
>
> Albert
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