[gmx-users] Commands to run simulations using multiple GPU's in version 5.0.1

[Johnny Lu]

Actually i am trying to find the answer to the same question now.

manual 4.6.7/appendix D/mdrun
says

-gpu_id
string
List of GPU device id-s to use, specifies the per-node PP rank to GPU
mapping

On Tue, Sep 23, 2014 at 11:07 PM, Siva Dasetty <sdasett at g.clemson.edu>
wrote:

> Thank you Lu for the reply.
>
> As I have mentioned in the post, I have already tried those options but it
> didn't work. Kindly please let me know if you have anymore suggestions.
>
> Thank you,
>
> On Tue, Sep 23, 2014 at 8:41 PM, Johnny Lu <johnny.lu128 at gmail.com> wrote:
>
> > Try -nt, -ntmpi, -ntomp, -np  (one at a time) ?
> > I forget about what I tried now.... But I just stop the mdrun, and then
> > read the log file.
> > Also can look for the mdrun page in the offical manual (pdf) and try this
> > page:
> >
> >
> http://www.gromacs.org/Documentation/Gromacs_Utilities/mdrun?highlight=mdrun
> >
> >
> > On Mon, Sep 22, 2014 at 6:46 PM, Siva Dasetty <sdasett at g.clemson.edu>
> > wrote:
> >
> > > Dear  All,
> > >
> > > I am trying to run NPT simulations using GROMACS version 5.0.1 of a
> > system
> > > of size 140k atoms (protein+water systems) with 2 or more GPU's
> > > (model=k20); 8 cores (or more); and 1 or more nodes. I am trying to
> > > understand how to run simulations using multiple gpus on more than one
> > > node. I  get the following errors/output when I run the simulation
> using
> > > the following commands:-
> > >
> > > Note: time-step used = 2 fs and total number of steps = 20000
> > >
> > > First 4 cases are using single GPU and cases 5-8 are using 2 GPU's.
> > >
> > > 1. 1 node, 8 cpus, 1 gpu
> > > export OMP_NUM_THREADS = 8
> > > command used-  mdrun -s topol.tpr  -gpu_id 0
> > > Speed - 5.8 ns/day
> > >
> > > 2.  1 node, 8 cpus, 1 gpu
> > > export OMP_NUM_THREADS = 16
> > > command used-  mdrun -s topol.tpr   -gpu_id 0
> > > Speed - 4.7 ns/day
> > >
> > > 3. 1 node, 8cpus, 1gpu
> > > mdrun -s topol.tpr -ntomp 8  -gpu_id 0
> > > Speed- 5.876 ns/day
> > >
> > > 4. 1 node, 8cpus, 1gpu
> > > mdrun -s topol.tpr -ntomp 16  -gpu_id 0
> > > Fatal Error: Environment variable OMP_NUM_THREADS (8) and the number of
> > > threads requested on  the command line (16) have different values.
> Either
> > > omit one, or set them both
> > >  to the same value.
> > >
> > > Question for 3 and 4 : Do I need to always use OMP_NUM_THREADS or is
> > there
> > > a way ntomp overwrites the environment settings?
> > >
> > >
> > > 5. 1 node, 8cpus , 2gpus
> > > export OMP_NUM_THREADS = 8
> > > mpirun -np 2 mdrun -s topol.tpr -pin on  -gpu_id 01
> > > Speed - 4.044 ns/day
> > >
> > > 6. 2 nodes, 8cpus , 2 gpus
> > > export OMP_NUM_THREADS = 8
> > > mpirun -np 2 mdrun -s topol.tpr -pin on  -gpu_id 01
> > > Speed - 3.0 ns/day
> > >
> > > Are the commands that I used for 5 and 6 correct?
> > >
> > > 7. I also used (1node, 8 cpus, 2 gpus)
> > >  mdrun -s topol.tpr -ntmpi 2 -ntomp 8  -gpu_id 01
> > > but this time I get a fatal error: thread mpi's are requested but
> gromacs
> > > is not compiled with thread MPI.
> > >
> > > Question: Isn't thread MPI enabled by default?
> > >
> > > 8. Finally, I recompiled Gromacs without OpenMP and re-ran case 1 but
> > this
> > > time there is a fatal error "More than 1 OpenMP thread requested, but
> > > Gromacs was compiled without OpenMP support."
> > > command : mdrun -s topol.tpr  (no environment settings)  -gpu_id 0
> > > Question: Here again, I assumed thread MPI is enabled by default and I
> > > think Gromacs still assumes OpenMp thread settings. Am i doing
> something
> > > wrong here?
> > >
> > > Thanks in advance for your help
> > >
> > > --
> > > Siva
> > > --
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>
>
> --
> Siva
> --
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