[gmx-users] why two GTX780ti is slower?

[Szilárd Páll]

This just tells that two GPU-s were detected but only the first one
was automatically selected to be used - presumably because you
manually specified the number of ranks (-np or -ntmpi) to be one.

However, your mail contains neither the command line you started mdrun
with, nor (a link to) the log file mdrun produces.

--
Szilárd


On Wed, May 14, 2014 at 2:43 PM, Albert <mailmd2011 at gmail.com> wrote:
> Hi Mark:
>
> thanks a lot for the messages. In most cases, job failed with following
> messages if I used intel MPI to evoke two GPU:
>
> [mpiexec at cudaA.compuBio] HYDU_getfullhostname
> (./utils/others/others.c:136): getaddrinfo error (hostname: cudaA.compuBio,
> error: Name or service not known)
> [mpiexec at cudaA.compuBio] HYDU_sock_create_and_listen_portstr
> (./utils/sock/sock.c:999): unable to get local hostname
> [mpiexec at cudaA.compuBio] HYD_pmci_launch_procs
> (./pm/pmiserv/pmiserv_pmci.c:313): unable to create PMI port
> [mpiexec at cudaA.compuBio] main (./ui/mpich/mpiexec.c:877): process manager
> returned error launching processes
>
>
> for one GPU job, here is the informations:
>
> 2 GPUs detected on host cudaA.compuBio:
>   #0: NVIDIA GeForce GTX 780 Ti, compute cap.: 3.5, ECC:  no, stat:
> compatible
>   #1: NVIDIA GeForce GTX 780 Ti, compute cap.: 3.5, ECC:  no, stat:
> compatible
>
> 1 GPU auto-selected for this run.
> Mapping of GPU to the 1 PP rank in this node: #0
>
>
> NOTE: potentially sub-optimal launch configuration, mdrun_mpi started with
> less
>       PP MPI process per node than GPUs available.
>       Each PP MPI process can use only one GPU, 1 GPU per node will be used.
>
> thank you verymuch.
>
>
> 2014-05-14 9:11 GMT+02:00 Mark Abraham <mark.j.abraham at gmail.com>:
>
>> 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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