[gmx-developers] Fortran acceleration + OpenMP strangeness

[Szilárd Páll]

Hi,

I bumped into a strange issue when verifying the nbnxn code with
Jenkins. Using the Fortran kernels, while the appropriate OpenMP flag
is used and mdrun compiles fine, some tools fail to compile with a
weird message complaining about missing symbols:

../gmxlib/libgmx.so.6: undefined reference to `omp_get_thread_num'
../gmxlib/libgmx.so.6: undefined reference to `GOMP_parallel_end'
../gmxlib/libgmx.so.6: undefined reference to `omp_get_num_threads'
../gmxlib/libgmx.so.6: undefined reference to `omp_set_num_threads'
../gmxlib/libgmx.so.6: undefined reference to `GOMP_parallel_start'
../gmxlib/libgmx.so.6: undefined reference to `omp_get_max_threads'

i) Does anybody have an idea what could be wrong?

ii) For what platforms are the fortran kernels still useful? If there
is any platform where they provide a faster alternative to the plain C
kernels, we should definitely keep them. Otherwise, deprecating them
is an option.

Cheers,
--
Szilárd