[gmx-developers] Running Gromacs on GPUs on multiple machines

[Vedran Miletić]

2014-05-29 16:36 GMT+02:00 Anders Gabrielsson <andgab at kth.se>:
> You'll probably have to supply -npernode/-ppn too so that your mpirun
> doesn't put all MPI ranks on the same host.
>
> /Anders
>
> On 29 May 2014, at 13:17, Vedran Miletić <rivanvx at gmail.com> wrote:
>
> Fatal error:
> Incorrect launch configuration: mismatching number of PP MPI processes
> and GPUs per node.
> mdrun_mpi was started with 5 PP MPI processes per node, but you provided 1
> GPU.

Hi Anders,

thanks for your response. Weirdly enough, mpirun actually doesn't run
processes all on one node, it distributes them as equally as possible,
going around your hostfile in a round-robin fashion. (I verified this
by running hostname.)

However, it seems that for some reason Gromacs assumes mpirun does run
5 processes on a single node. Regardless, i tried

mpirun -np 5 -npernode 1 -hostfile ... mdrun_mpi -v -deffnm ... -gpu_id 0

but it produces the same error. Anything else I could try?

Regards,
Vedran