[gmx-developers] Hardware threads vs. OpenMP threads

[Berk Hess]

PS There is something strange on that machine. If Gromacs detects 16 
threads, omp_get_num_procs should return 16, not 8.

Berk

On 2015-06-04 12:49, Berk Hess wrote:
> Hi,
>
> I don't think anything changed in the master branch.
>
> But we do adhere to the OpenMP environment. The value reported in the 
> message comes from omp_get_num_procs, which should be a report about 
> the hardware available. OMP_NUM_THREADS sets the number of OpenMP 
> threads to use, that is respected.
>
> Cheers,
>
> Berk
>
> On 2015-06-04 11:21, David van der Spoel wrote:
>> Hi,
>>
>> why does GROMACS in the master branch not adhere to the OpenMP 
>> environment?
>>
>> Number of hardware threads detected (16) does not match the number 
>> reported by OpenMP (8).
>> Consider setting the launch configuration manually!
>> Reading file md.tpr, VERSION 5.1-beta1-dev-20150603-99a1e1f-dirty 
>> (single precision)
>> Changing nstlist from 10 to 40, rlist from 1.1 to 1.1
>>
>> Using 1 MPI process
>> Using 16 OpenMP threads
>>
>> Cheers,
>