From: Ryan Moulday Date: Mon, 16 Sep 2024 03:40:39 +0000 (-0400) Subject: Make improvements to the WorkStream colored implementation X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F17707%2Fhead;p=dealii.git Make improvements to the WorkStream colored implementation --- diff --git a/include/deal.II/base/work_stream.h b/include/deal.II/base/work_stream.h index 007516f8c0..31a54c514c 100644 --- a/include/deal.II/base/work_stream.h +++ b/include/deal.II/base/work_stream.h @@ -1181,7 +1181,6 @@ namespace WorkStream { tf::Executor &executor = MultithreadInfo::get_taskflow_executor(); - tf::Taskflow taskflow; using ScratchAndCopyDataObjects = typename internal:: ScratchAndCopyDataObjects; @@ -1190,12 +1189,11 @@ namespace WorkStream Threads::ThreadLocalStorage thread_safe_scratch_and_copy_data_list; - // These are used to establish task dependencies. These are barrier - // tasks which are dependent on all tasks in the same "color" to be - // completed before allowing any tasks in the next "color" to be worked - // on. - tf::Task last_color; - tf::Task next_color; + tf::Taskflow taskflow; + + // Create a "future" object which eventually contains the execution + // result of a taskflow graph and can be used to yield execution + tf::Future execution_future; const bool have_worker = (static_cast 0) { - // Keep a handle to the last color. Tasks in taskflow are - // basically handles to internally stored data, so this does not - // perform a copy: - if (!next_color.empty()) - last_color = next_color; - // A placeholder task is a task object which respects dependencies - // but is empty (contains no work). The name is useful when - // examining a visualization of the graph through Taskflow's - // supported visualization tools. - if (color < colored_iterators.size() - 1) - next_color = taskflow.placeholder().name("color border"); - // For each cell queue up a combined worker and copier task. These // are not yet run. for (const Iterator &it : colored_iterators[color]) { - auto worker_task = - taskflow - .emplace( - [it = - it, // make a copy of the reference to the iterator - have_worker, - have_copier, - &thread_safe_scratch_and_copy_data_list, - &sample_scratch_data, - &sample_copy_data, - &worker, - &copier]() { - ScratchData *scratch_data = nullptr; - CopyData *copy_data = nullptr; - - ScratchAndCopyDataList &scratch_and_copy_data_list = - thread_safe_scratch_and_copy_data_list.get(); - // See if there is an unused object. if so, grab it - // and mark it as used. - for (typename ScratchAndCopyDataList::iterator p = - scratch_and_copy_data_list.begin(); - p != scratch_and_copy_data_list.end(); - ++p) - { - if (p->currently_in_use == false) - { - scratch_data = p->scratch_data.get(); - copy_data = p->copy_data.get(); - p->currently_in_use = true; - break; - } - } - // If no element in the list was found, create one and - // mark it as used. - if (scratch_data == nullptr) - { - Assert(copy_data == nullptr, ExcInternalError()); - scratch_and_copy_data_list.emplace_back( - std::make_unique( - sample_scratch_data), - std::make_unique(sample_copy_data), - true); - scratch_data = scratch_and_copy_data_list.back() - .scratch_data.get(); - copy_data = scratch_and_copy_data_list.back() - .copy_data.get(); - } - if (have_worker) - worker(it, *scratch_data, *copy_data); - if (have_copier) - copier(*copy_data); - - // Mark objects as free to be used again. - for (typename ScratchAndCopyDataList::iterator p = - scratch_and_copy_data_list.begin(); - p != scratch_and_copy_data_list.end(); - ++p) - { - if (p->scratch_data.get() == scratch_data) - { - Assert(p->currently_in_use == true, - ExcInternalError()); - p->currently_in_use = false; - } - } - }) - .name("worker_and_copier"); - // If we are on the last color we do not need to add a barrier - // at the end of the graph. Otherwise we force the next color - // barrier to wait until the current task (and thus all tasks - // in this color group) are finished. - if (color < colored_iterators.size() - 1) - worker_task.precede(next_color); - - // The first group of tasks does not depend on a previous - // barrier being reached. Otherwise, we ensure the previous - // barrier must resolve before any new tasks in the next color - // can start. - if (!last_color.empty()) - last_color.precede(worker_task); + taskflow + .emplace( + [it = it, // make a copy of the reference to the iterator + have_worker, + have_copier, + &thread_safe_scratch_and_copy_data_list, + &sample_scratch_data, + &sample_copy_data, + &worker, + &copier]() { + ScratchData *scratch_data = nullptr; + CopyData *copy_data = nullptr; + + ScratchAndCopyDataList &scratch_and_copy_data_list = + thread_safe_scratch_and_copy_data_list.get(); + // See if there is an unused object. if so, grab it + // and mark it as used. + for (typename ScratchAndCopyDataList::iterator p = + scratch_and_copy_data_list.begin(); + p != scratch_and_copy_data_list.end(); + ++p) + { + if (p->currently_in_use == false) + { + scratch_data = p->scratch_data.get(); + copy_data = p->copy_data.get(); + p->currently_in_use = true; + break; + } + } + // If no element in the list was found, create one and + // mark it as used. + if (scratch_data == nullptr) + { + Assert(copy_data == nullptr, ExcInternalError()); + scratch_and_copy_data_list.emplace_back( + std::make_unique( + sample_scratch_data), + std::make_unique(sample_copy_data), + true); + scratch_data = scratch_and_copy_data_list.back() + .scratch_data.get(); + copy_data = + scratch_and_copy_data_list.back().copy_data.get(); + } + if (have_worker) + worker(it, *scratch_data, *copy_data); + if (have_copier) + copier(*copy_data); + + // Mark objects as free to be used again. + for (typename ScratchAndCopyDataList::iterator p = + scratch_and_copy_data_list.begin(); + p != scratch_and_copy_data_list.end(); + ++p) + { + if (p->scratch_data.get() == scratch_data) + { + Assert(p->currently_in_use == true, + ExcInternalError()); + p->currently_in_use = false; + } + } + }) + .name("worker_and_copier"); } + if (color > 0) + // Wait for the previous color to finish executing + execution_future.wait(); + execution_future = executor.run(std::move(taskflow)); } - // Now we run all the tasks in the task graph. They will be run in - // parallel and are eligible to run when their dependencies established - // above are met. - executor.run(taskflow).wait(); + // Wait for our final execution to finish + if (colored_iterators.size() > 0) + execution_future.wait(); } } // namespace taskflow_colored # endif // DEAL_II_WITH_TASKFLOW