From: Martin Kronbichler Date: Mon, 7 Dec 2015 13:13:50 +0000 (+0100) Subject: Speedup extract_locally_relevant_dofs X-Git-Tag: v8.4.0-rc2~172^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=186108975a53a3d4ae53415a543046a635aa5879;p=dealii.git Speedup extract_locally_relevant_dofs --- diff --git a/source/dofs/dof_tools.cc b/source/dofs/dof_tools.cc index e56f5b1322..8f12f1d464 100644 --- a/source/dofs/dof_tools.cc +++ b/source/dofs/dof_tools.cc @@ -949,12 +949,14 @@ namespace DoFTools // now add the DoF on the adjacent ghost cells to the IndexSet - // Note: It is not worth it to cache intermediate data in a set because - // add_indices is more efficient. I also benchmarked skipping the - // locally_owned_dofs by doing locally_owned_dofs().is_element() but - // that is also slower unless 70%+ of the DoFs are locally owned and they - // are contiguous. - Timo Heister + // Note: For certain meshes (in particular in 3D and with many + // processors), it is really necessary to cache intermediate data. After + // trying several objects such as std::set, a vector that is always kept + // sorted, and a vector that is initially unsorted and sorted once at the + // end, the latter has been identified to provide the best performance. + // Martin Kronbichler std::vector dof_indices; + std::vector dofs_on_ghosts; typename DoFHandlerType::active_cell_iterator cell = dof_handler.begin_active(), endc = dof_handler.end(); @@ -963,9 +965,15 @@ namespace DoFTools { dof_indices.resize(cell->get_fe().dofs_per_cell); cell->get_dof_indices(dof_indices); - dof_set.add_indices(dof_indices.begin(), dof_indices.end()); + for (unsigned int i=0; i dof_indices; + std::vector dofs_on_ghosts; typename DoFHandlerType::cell_iterator cell = dof_handler.begin(level), endc = dof_handler.end(level); @@ -1001,9 +1011,16 @@ namespace DoFTools dof_indices.resize(cell->get_fe().dofs_per_cell); cell->get_mg_dof_indices(dof_indices); - dof_set.add_indices(dof_indices.begin(), dof_indices.end()); + for (unsigned int i=0; i