[gmx-users] MPI and OpenMP threads

[Alexander Alexander]

Dear Gromacs user,

Gromacs works fine for me with the below first group of parallel
environment and threads but it crashed with the second group complaining
that:

libgomp: Thread creation failed: Resource temporarily unavailable
Thread creation failed: Resource temporarily unavailable


Works fine  :-)
----------------------------------
#$ -pe smp 16

gmx mdrun -deffnm nvt -s nvt.tpr -ntomp 4 -ntmpi 4
------------------------------------
#$ -pe smp 6

gmx mdrun -deffnm nvt -s nvt.tpr -ntomp 2 -ntmpi 3
--------------------------------------


Crashed  :-(
------------------------------------
#$ -pe smp 32

gmx mdrun -deffnm nvt -s nvt.tpr -ntomp 4 -ntmpi 8
-------------------------------------
#$ -pe smp 32

gmx mdrun -deffnm nvt -s nvt.tpr -ntomp 2 -ntmpi 16
-------------------------------------
#$ -pe orte_sl32* 64

gmx mdrun -deffnm nvt -s nvt.tpr -ntomp 32 -ntmpi 2
---------------------------------------

Here is the properties of the machine which I am using for Gromacs:

Running on 1 node with total 64 cores, 64 logical cores
Hardware detected:
  CPU info:
    Vendor: AuthenticAMD
    Brand:  AMD Opteron(TM) Processor 6276
    SIMD instructions most likely to fit this hardware: AVX_128_FMA
    SIMD instructions selected at GROMACS compile time: AVX_128_FMA


Any body knows what is the reason please?

Best regards,
Alex