Hi,
I run three simulations on 1 node with 3 GPU by using an increasing number of
GPUs.
This is my system:
___________________________________________________________________
1 node with total 36 cores, 72 logical cores, 3 compatible GPUs
GROMACS version: 2018.2
Precision: single
Memory model: 64 bit
MPI library: thread_mpi
OpenMP support: enabled (GMX_OPENMP_MAX_THREADS = 64)
GPU support: CUDA
SIMD instructions: AVX2_256
FFT library: fftw-3.3.8-sse2-avx-avx2-avx2_128-avx512
RDTSCP usage: enabled
TNG support: enabled
Hwloc support: hwloc-1.11.0
Tracing support: disabled
Built on: 2018-08-01 09:03:03
GPU info:
Number of GPUs detected: 3
#0: NVIDIA Tesla V100-PCIE-32GB, compute cap.: 7.0, ECC: yes, stat:
compatible
#1: NVIDIA Tesla V100-PCIE-32GB, compute cap.: 7.0, ECC: yes, stat:
compatible
#2: NVIDIA Tesla V100-PCIE-32GB, compute cap.: 7.0, ECC: yes, stat:
compatible
___________________________________________________________________
These are the launched commands on two different system size and related
performances:
Command
ns/day
h/ns
Alchol Dehydrogenase system (95561 atoms)
gmx mdrun -deffnm topol -nb gpu -pme gpu -ntmpi 1 -ntomp 12
53.355
0.45
gmx mdrun -deffnm topol -nb gpu -pme gpu -ntmpi 2 -ntomp 12 -npme 1 -gputasks 01
53.176
0.451
gmx mdrun -deffnm topol -nb gpu -pme gpu -ntmpi 3 -ntomp 12 -npme 1 -gputasks
012
50.024
0.48
Villin system (4723 atoms)
gmx mdrun -deffnm topol -nb gpu -pme gpu -ntmpi 1 -ntomp 12
589.635
0.041
gmx mdrun -deffnm topol -nb gpu -pme gpu -ntmpi 2 -ntomp 12 -npme 1 -gputasks 01
727.139
0.033
gmx mdrun -deffnm topol -nb gpu -pme gpu -ntmpi 3 -ntomp 12 -npme 1 -gputasks
012
664.695
0.036
Despite the performances seems very strange, because by increasing the number
of GPUs in a big system I can't seeing a speedup, while in a small system the
performance's peak is reached with 2 GPU,
can I ask to all of you if I'm using the GPU's selection options in the right
way?
Moreover, I'm not sure about the right usage of -ntomp option, I thought to ask
in another session.
Thanks a lot!
Carmine
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