Hi,

Am 16.10.2016 um 20:34 schrieb Mahmood Naderan:

> Hi,
> I am running two softwares that use OMPI-2.0.1. Problem is that the CPU 
> utilization is low on the nodes.
> 
> 
> For example, see the process information below
> 
> [root@compute-0-1 ~]# ps aux | grep siesta
> mahmood  14635  0.0  0.0 108156  1300 ?        S    21:58   0:00 /bin/bash 
> /share/apps/chemistry/siesta-4.0-mpi201/spar/siesta.p1 A.fdf
> mahmood  14636  0.0  0.0 108156  1300 ?        S    21:58   0:00 /bin/bash 
> /share/apps/chemistry/siesta-4.0-mpi201/spar/siesta.p1 A.fdf
> mahmood  14637 61.6  0.2 372076 158220 ?       Rl   21:58   0:38 
> /share/apps/chemistry/siesta-4.0-mpi201/spar/siesta
> mahmood  14639 59.6  0.2 365992 154228 ?       Rl   21:58   0:37 
> /share/apps/chemistry/siesta-4.0-mpi201/spar/siesta
> 
> 
> Note that the cpu utilization is the third column. The "siesta.pl" script is
> 
> #!/bin/bash
> BENCH=$1
> export OMP_NUM_THREADS=1
> /share/apps/chemistry/siesta-4.0-mpi201/spar/siesta < $BENCH
> 
> 
> 
> 
> I also saw a similar behavior from Gromacs which has been discussed at 
> https://mailman-1.sys.kth.se/pipermail/gromacs.org_gmx-users/2016-October/108939.html
> 
> It seems that there is a tricky thing with OMPI. Any idea is welcomed.

Sounds like the two jobs are using the same cores by automatic core binding as 
one instance doesn't know anything about the other. For a first test you can 
start both with "mpiexec --bind-to none ..." and check whether you see a 
different behavior.

`man mpiexec` mentions some hints about threads in applications.

-- Reuti

> 
> 
> Regards,
> Mahmood
> 
> 
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