[gmx-users] GPU and MPI

Albert mailmd2011 at gmail.com
Mon Sep 8 20:39:14 CEST 2014


Helo Yunlong:

thx a lot for the reply.

It works in Gromacs-4.6.5, but it does NOT in Gromacs-5.0.1. I used the 
following command:

mpirun -np 2 mdrun_mpi -v -s npt2.tpr -c npt2.gro -x npt2.xtc -g 
npt2.log -gpu_id 01 -ntomp 10


but it always failed with messages:


2 GPUs detected on host cudaB:
   #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

2 GPUs user-selected for this run.
Mapping of GPUs to the 1 PP rank in this node: #0, #1


-------------------------------------------------------
Program mdrun_mpi, VERSION 5.0.1
Source code file: 
/soft2/plumed-2.2/gromacs-5.0.1/src/gromacs/gmxlib/gmx_detect_hardware.c, line: 
359

Fatal error:
Incorrect launch configuration: mismatching number of PP MPI processes 
and GPUs per node.
mdrun_mpi was started with 1 PP MPI process per node, but you provided 2 
GPUs.
For more information and tips for troubleshooting, please check the GROMACS
website at http://www.gromacs.org/Documentation/Errors



However, this command works fine in Gromacs-4.6.5, and I don't know why 
it failed in 5.0.1.

best

Albert


On 09/08/2014 05:33 PM, Yunlong Liu wrote:
> For using two GPU, just add option -gpu_id 01 to specify each gpu for each MPI process.
>
>
> Yunlong



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