Hi Chenchen
Just so that I understand: are you currently solving the problem using the same
approach (i.e. distributing the cells, solving the microscopic problem at each
quadrature point of the cells). You have the solution and now you want to write
it into a global history vector?
When you say it can not save any time - what do you mean? You have a very small
number of processors (4 I think) and the data you are writing looks small.
Would you expect to see a speed up?
There might be better ways to write multiple chunks of data into a vector than
what you have suggested (your approach seems a bit low level). Perhaps someone
can suggest an alternative strategy? A map between the cell user pointer and
the data you want to store might be a better idea.
A
>
> Let's simplify the problem as:
> First, we have a 1-D macro mesh, and at each element (interval) we have 2
> quadrature points. On each quadrature point, we generate a new Vector, i.e.,
> solution_x. Then, I want to remember this Vector by writing it into
> local_quadrature_point_history().
>
> I have written the following code, expecting that we can divide the entire
> elements into 4 sub_ranges, and write new Vector to
> local_quadrature_point_history() in parallel. But it turns out that it cannot
> save any computational time. Can anyone give me any suggestions? Thank you!
>
>
> void Step3::Write_problem_on_cell_range (DoFHandler<1>::cell_iterator
> &range_begin,
>
>
> DoFHandler<1>::cell_iterator &range_end)
>
> {
>
> const unsigned int n_q_points = quadrature_formula_MACRO.size();
>
> static Threads::Mutex mutex;
>
> Threads::Mutex::ScopedLock lock (mutex);
>
>
> DoFHandler<1>::cell_iterator cell_MACRO = range_begin, endc_MACRO =
> range_end;
>
> for (; cell_MACRO!=endc_MACRO; ++cell_MACRO)
>
> {
>
> // build history
>
> PointHistory<1> *local_quadrature_points_history_MACRO
>
> = reinterpret_cast<PointHistory<1> *>(cell_MACRO->user_pointer());
>
>
> // BEGIN RVE problem
>
> for (unsigned int q_index = 0; q_index<n_q_points; ++q_index)
>
> {
>
> solution_x_RVE[0] = 1; solution_x_RVE[1] = 2;
>
> // Write
>
> local_quadrature_points_history_MACRO[q_index].solution_x_RVE_h =
> solution_x_RVE;
>
> }
>
> }
>
> }
>
>
>
> void Step3::Write_problem ()
>
> {
>
> static unsigned int n_virtual_cores = MultithreadInfo::n_threads();
>
> Threads::ThreadGroup<void> threads;
>
>
> std::vector<std::pair<DoFHandler<1>::cell_iterator,DoFHandler<1>::cell_iterator>
> >
>
> sub_ranges = Threads::split_range
> <DoFHandler<1>::cell_iterator>(dof_handler_MACRO.begin_active(),
>
>
> dof_handler_MACRO.end(),
>
>
> n_virtual_cores);
>
>
> for (unsigned int t=0; t<n_virtual_cores; ++t)
>
> threads += Threads::new_thread (&Step3::Write_problem_on_cell_range,
> *this,
>
>
> sub_ranges[t].first, sub_ranges[t].second);
>
> threads.join_all();
>
> }
>
>
>
>
>
>
>
>
>
> Best,
>
> Chenchen
>
>
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