Jacques Lucke
e130903060
We often call `parallel_for` in places with very variable sized workloads. When many elements are processed, using multi-threading is great, but when processing few elements (possibly many times) using `parallel_for` can result in significant overhead. I measured that this improves performance by >20% in the refactored realize instances code I'm working on separately. The change might also help with debugging sometimes, because the stack trace is smaller and contains fewer irrevelant symbols.
117 lines
3.4 KiB
C++
117 lines
3.4 KiB
C++
/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#pragma once
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/** \file
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* \ingroup bli
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*/
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#ifdef WITH_TBB
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/* Quiet top level deprecation message, unrelated to API usage here. */
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# if defined(WIN32) && !defined(NOMINMAX)
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/* TBB includes Windows.h which will define min/max macros causing issues
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* when we try to use std::min and std::max later on. */
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# define NOMINMAX
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# define TBB_MIN_MAX_CLEANUP
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# endif
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# include <tbb/blocked_range.h>
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# include <tbb/parallel_for.h>
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# include <tbb/parallel_for_each.h>
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# include <tbb/parallel_reduce.h>
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# include <tbb/task_arena.h>
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# ifdef WIN32
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/* We cannot keep this defined, since other parts of the code deal with this on their own, leading
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* to multiple define warnings unless we un-define this, however we can only undefine this if we
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* were the ones that made the definition earlier. */
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# ifdef TBB_MIN_MAX_CLEANUP
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# undef NOMINMAX
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# endif
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# endif
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#endif
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#include "BLI_index_range.hh"
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#include "BLI_utildefines.h"
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namespace blender::threading {
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template<typename Range, typename Function>
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void parallel_for_each(Range &range, const Function &function)
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{
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#ifdef WITH_TBB
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tbb::parallel_for_each(range, function);
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#else
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for (auto &value : range) {
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function(value);
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}
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#endif
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}
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template<typename Function>
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void parallel_for(IndexRange range, int64_t grain_size, const Function &function)
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{
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if (range.size() == 0) {
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return;
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}
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#ifdef WITH_TBB
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/* Invoking tbb for small workloads has a large overhead. */
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if (range.size() >= grain_size) {
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tbb::parallel_for(
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tbb::blocked_range<int64_t>(range.first(), range.one_after_last(), grain_size),
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[&](const tbb::blocked_range<int64_t> &subrange) {
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function(IndexRange(subrange.begin(), subrange.size()));
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});
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return;
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}
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#else
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UNUSED_VARS(grain_size);
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#endif
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function(range);
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}
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template<typename Value, typename Function, typename Reduction>
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Value parallel_reduce(IndexRange range,
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int64_t grain_size,
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const Value &identity,
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const Function &function,
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const Reduction &reduction)
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{
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#ifdef WITH_TBB
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return tbb::parallel_reduce(
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tbb::blocked_range<int64_t>(range.first(), range.one_after_last(), grain_size),
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identity,
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[&](const tbb::blocked_range<int64_t> &subrange, const Value &ident) {
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return function(IndexRange(subrange.begin(), subrange.size()), ident);
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},
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reduction);
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#else
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UNUSED_VARS(grain_size, reduction);
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return function(range, identity);
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#endif
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}
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/** See #BLI_task_isolate for a description of what isolating a task means. */
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template<typename Function> void isolate_task(const Function &function)
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{
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#ifdef WITH_TBB
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tbb::this_task_arena::isolate(function);
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#else
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function();
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#endif
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}
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} // namespace blender::threading
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