[Trilinos-Users] [Kokkos-Developers] [EXTERNAL] [12.2.1] MueLu/Kokkos OpenMP configuration/macros issue

Christian Trott crtrott at sandia.gov
Sun Oct 18 02:55:21 EDT 2015

Oh ok. That almost surely means one of two things:
(i) MueLu is using Kokkos::OpenMP explicitly instead of 
(ii) Something screwed up the configuration whereas KOKKOS_HAVE_OPENMP 
is defined without enabling openmp in the compiler.
MueLU would only check the KOKKOS_HAVE_OPENMP flag, which is probably 
the right thing to do.
What we should add in Kokkos is a more meaningfull error (and early 
exit) if KOKKOS_HAVE_OPENMP is defined but _OPENMP is not.


On 10/18/2015 12:30 AM, Denis Davydov wrote:
> It’s not that much about the usage of OpenMP but rather about inconsistencies inside packages and their configuration when OpenMP=ON,
> which in turn leads to compiler errors when using trilinos.
> Roughly, It seems that Kokkos was clever to disable OpenMP when user did not provide those compiler flags("-fope nmp"), whereas MueLu still thinks that OpenMP is enabled
> and thus the compiler error.
> Denis.
>> On 18 Oct 2015, at 08:18, Christian Trott <crtrott at sandia.gov> wrote:
>> If what you suggests fixes it then you tried to compile with the OpenMP backend, without enabling OpenMP in the compiler (i.e. what Si indirectly suggested).
>> We do not allow you to use the OpenMP backend if OpenMP is not enabled in the compiler. By removing our guards you circumvent that. While this means
>> that you might actually get your code to compiler, it is unlikely that it will run correctly.
>> Christian

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