On Thu, Jul 5, 2018 at 12:41 PM Tobin Isaac <tis...@cc.gatech.edu> wrote:
> On Thu, Jul 05, 2018 at 09:28:16AM -0400, Mark Adams wrote: > > > > > > > > > Please share the results of your experiments that prove OpenMP does not > > > improve performance for Mark’s users. > > > > > > > This obviously does not "prove" anything but my users use OpenMP > primarily > > because they do not distribute their mesh metadata. They can not > replicated > > the mesh on every core, on large scale problems and shared memory allows > > them to survive. They have decided to use threads as opposed to MPI > shared > > memory. (Not a big deal, once you decide not to use distributed memory > the > > damage is done and NERSC seems to be OMP centric so they can probably get > > better support for OMP than MPI shared memory.) > > Out of curiosity, is the mesh immutable for a full simulation or adaptive? > If it's immutable, that seems like a poster child for the "private by > default, shared by choice" paradigm. > This is Chombo so it is dynamic. > > > BTW, PETSc does support OMP, that is what I have been working on testing > > for the last few weeks. First with Hypre (numerics are screwed up from an > > apparent compiler bug or a race condition of some sort; it fails at > higher > > levels of optimization), and second with MKL kernels. The numerics are > > working with MKL and we are working on packaging this up to deliver to a > > user (they will test performance). >