科学计算中的有限元slides.40

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template <int dim> void MyProblem<dim>::assemble_system () { … for (cell=dof_handler.begin_active(); …) { fe_values.reinit (cell); ...assemble local contribution... ...copy local contribution into global matrix/rhs vector... } }
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void MyProblem<dim>::assemble_on_cell_range (cell_iterator &range_begin, cell_iterator &range_end); void MyProblem<dim>::assemble_system () { Threads::ThreadGroup<void> threads; std::vector<std::pair<cell_iterator, cell_iterator> > sub_ranges = Threads::split_range (dof_handler.begin_active(), dof_handler.end(), n_virtual_cores); for (t=0; t<n_virtual_cores; ++t) threads += Threads::new_thread (&MyProblem<dim>::assemble_on_cell_range, this, sub_ranges[t].first, sub_ranges[t].second); threads.join_all (); }
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template <int dim> void MyProblem<dim>::setup_system () { dof_handler.distribute_dofs(); DoFTools::make_hanging_node_constraints (…); // 1 DoFTools::make_sparsity_pattern (…); // 2 VectorTools::interpolate_boundary_values (…); // 3 … }
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void MyProblem<dim>::assemble_on_one_cell (cell_iterator &cell) {…} void MyProblem<dim>::assemble_system () { Threads::ThreadGroup<void> threads; for (cell=dof_handler.begin_active(); …) threads += Threads::new_thread (&MyProblem<dim>::assemble_on_one_cell, this, cell); threads.join_all (); }
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void MyProblem<dim>::assemble_on_one_cell (cell_iterator &cell) {…} void MyProblem<dim>::assemble_system () { Threads::ThreadGroup<void> threads; for (cell=dof_handler.begin_active(); …) threads += Threads::new_task (&MyProblem<dim>::assemble_on_one_cell, this, cell); threads.join_all (); }
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template <int dim> void MyProblem<dim>::setup_system () { dof_handler.distribute_dofs(); DoFTools::make_hanging_node_constraints (…); DoFTools::make_sparsity_pattern (…); VectorTools::interpolate_boundary_values (…); constraints.condense (sparsity_pattern); }
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template <int dim> void MyProblem<dim>::setup_system () { dof_handler.distribute_dofs(); pthread_t thread1, thread2, thread3; thread1 = pthread_create (&DoFTools::make_hanging_node_constraints, …); thread2 = pthread_create (&DoFTools::make_sparsity_pattern, …); thread3 = pthread_create (&VectorTools::interpolate_boundary_values, …); pthread_join (thread1); … } // and same for thread2, thread3
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template <int dim> void MyProblem<dim>::setup_system () { Threads::Task<void> t1, t2, t3, t4, t5; t1 = Threads::new_task (dof_handler, distribute_dofs, ...); t2 = t1.enqueue (DoFTools::make_hanging_node_constraints, …); t3 = t1.enqueue (DoFTools::make_sparsity_pattern, …); t4 = t1.enqueue (VectorTools::interpolate_boundary_values (…); t5 = (t2,t3).enqueue (constraints, condense, sparsity_pattern); t4.join (); t5.join (); }
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template <int dim> void MyProblem<dim>::setup_system () { dof_handler.distribute_dofs(); Threads::Thread<void> thread1, thread2, thread3; thread1 = Threads::new_thread (&DoFTools::make_hanging_node_constraints, …); thread2 = Threads::new_thread (&DoFTools::make_sparsity_pattern, …); thread3 = Threads::new_thread (&VectorTools::interpolate_boundary_values, …); thread1.join (); // and same for thread2, thread3 … }