Dear Bruno, > The suggested compilation options for Trilinos do not suggest the use of > OpenMP and the flag is not enabled by default.
Can you please indicate where you read this? I’m looking at our documentation for interfacing to external libraries, i.e. https://dealii.org/9.0.0/readme.html <https://dealii.org/9.0.0/readme.html> https://dealii.org/9.0.0/external-libs/trilinos.html <https://dealii.org/9.0.0/external-libs/trilinos.html> and I don’t see any mention of OpenMP. > Does this mean that the compilation of Trilinos with the suggested flag > enables shared memory parallelism when using the TrilinosWrappers function, > or is it necessary to compile Trilinos with openmp or threads enabled? Trilinos does its own thread management, so irrespective of whether you've built it with threading enabled (i.e. with the OpenMP or pthreads options enabled) enabling/disabling threading in deal.II will have no effect on this. What might be possible is that you could have scheduling conflicts, e.g. what is mentioned here https://software.intel.com/en-us/forums/intel-threading-building-blocks/topic/281761 <https://software.intel.com/en-us/forums/intel-threading-building-blocks/topic/281761> if you use multiple threading models in one code base. But I don’t know enough about the topic to say anything more than mention the potential issue. > What are the official guidelines for this? I would say that there are none — how you’re wanting to run your simulations (e.g. desktop, cluster computing, etc.) dictates what parallelism model (i.e. multi-threading, MPI, or hybrid) would work best for you. Would you care to elaborate more on this so that we could maybe make some suggestions? Best, Jean-Paul > On 03 Mar 2019, at 21:40, Bruno Blais <[email protected]> wrote: > > Hello everyone, > I have a quick question for which I have not found documentation. > The suggested compilation options for Trilinos do not suggest the use of > OpenMP and the flag is not enabled by default. > DEALII by default also compiles using TBB for shared memory parallelism. Does > this mean that the compilation of Trilinos with the suggested flag enables > shared memory parallelism when using the TrilinosWrappers function, or is it > necessary to compile Trilinos with openmp or threads enabled? > What are the official guidelines for this? > > Thanks a lot > Bruno > > -- > The deal.II project is located at http://www.dealii.org/ > <http://www.dealii.org/> > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > <https://groups.google.com/d/forum/dealii?hl=en> > --- > You received this message because you are subscribed to the Google Groups > "deal.II User Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
