212 lines
6.7 KiB
C++
212 lines
6.7 KiB
C++
/* SPDX-FileCopyrightText: 2023 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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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_invoke.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_function_ref.hh"
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#include "BLI_index_range.hh"
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#include "BLI_lazy_threading.hh"
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#include "BLI_utildefines.h"
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namespace blender {
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/**
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* Wrapper type around an integer to differentiate it from other parameters in a function call.
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*/
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struct GrainSize {
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int64_t value;
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explicit constexpr GrainSize(const int64_t grain_size) : value(grain_size) {}
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};
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} // namespace blender
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namespace blender::threading {
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template<typename Range, typename Function>
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inline 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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namespace detail {
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void parallel_for_impl(IndexRange range,
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int64_t grain_size,
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FunctionRef<void(IndexRange)> function);
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} // namespace detail
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template<typename Function>
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inline void parallel_for(IndexRange range, int64_t grain_size, const Function &function)
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{
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if (range.is_empty()) {
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return;
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}
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if (range.size() <= grain_size) {
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function(range);
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return;
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}
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detail::parallel_for_impl(range, grain_size, function);
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}
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/**
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* Move the sub-range boundaries down to the next aligned index. The "global" begin and end
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* remain fixed though.
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*/
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inline IndexRange align_sub_range(const IndexRange unaligned_range,
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const int64_t alignment,
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const IndexRange global_range)
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{
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const int64_t global_begin = global_range.start();
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const int64_t global_end = global_range.one_after_last();
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const int64_t alignment_mask = ~(alignment - 1);
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const int64_t unaligned_begin = unaligned_range.start();
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const int64_t unaligned_end = unaligned_range.one_after_last();
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const int64_t aligned_begin = std::max(global_begin, unaligned_begin & alignment_mask);
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const int64_t aligned_end = unaligned_end == global_end ?
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unaligned_end :
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std::max(global_begin, unaligned_end & alignment_mask);
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const IndexRange aligned_range{aligned_begin, aligned_end - aligned_begin};
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return aligned_range;
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}
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/**
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* Same as #parallel_for but tries to make the sub-range sizes multiples of the given alignment.
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* This can improve performance when the range is processed using vectorized and/or unrolled loops,
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* because the fallback loop that processes remaining values is used less often. A disadvantage of
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* using this instead of #parallel_for is that the size differences between sub-ranges can be
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* larger, which means that work is distributed less evenly.
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*/
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template<typename Function>
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inline void parallel_for_aligned(const IndexRange range,
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const int64_t grain_size,
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const int64_t alignment,
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const Function &function)
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{
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parallel_for(range, grain_size, [&](const IndexRange unaligned_range) {
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const IndexRange aligned_range = align_sub_range(unaligned_range, alignment, range);
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function(aligned_range);
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});
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}
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template<typename Value, typename Function, typename Reduction>
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inline 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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if (range.size() >= grain_size) {
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lazy_threading::send_hint();
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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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}
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#else
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UNUSED_VARS(grain_size, reduction);
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#endif
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return function(range, identity);
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}
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template<typename Value, typename Function, typename Reduction>
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inline Value parallel_reduce_aligned(const IndexRange range,
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const int64_t grain_size,
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const int64_t alignment,
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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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parallel_reduce(
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range,
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grain_size,
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identity,
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[&](const IndexRange unaligned_range, const Value &ident) {
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const IndexRange aligned_range = align_sub_range(unaligned_range, alignment, range);
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function(aligned_range, ident);
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},
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reduction);
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}
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/**
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* Execute all of the provided functions. The functions might be executed in parallel or in serial
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* or some combination of both.
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*/
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template<typename... Functions> inline void parallel_invoke(Functions &&...functions)
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{
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#ifdef WITH_TBB
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tbb::parallel_invoke(std::forward<Functions>(functions)...);
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#else
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(functions(), ...);
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#endif
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}
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/**
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* Same #parallel_invoke, but allows disabling threading dynamically. This is useful because when
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* the individual functions do very little work, there is a lot of overhead from starting parallel
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* tasks.
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*/
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template<typename... Functions>
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inline void parallel_invoke(const bool use_threading, Functions &&...functions)
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{
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if (use_threading) {
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lazy_threading::send_hint();
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parallel_invoke(std::forward<Functions>(functions)...);
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}
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else {
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(functions(), ...);
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}
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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> inline void isolate_task(const Function &function)
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{
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#ifdef WITH_TBB
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lazy_threading::ReceiverIsolation isolation;
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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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