[libcxx-commits] [pstl] e484c17 - [pstl] A cleanup fix for sort parallel algorithm.
via libcxx-commits
libcxx-commits at lists.llvm.org
Thu Mar 5 00:34:09 PST 2020
Author: Dvorskiy, Mikhail
Date: 2020-03-05T11:27:32+03:00
New Revision: e484c1759d410ab6229d17251fcd157b76ff840e
URL: https://github.com/llvm/llvm-project/commit/e484c1759d410ab6229d17251fcd157b76ff840e
DIFF: https://github.com/llvm/llvm-project/commit/e484c1759d410ab6229d17251fcd157b76ff840e.diff
LOG: [pstl] A cleanup fix for sort parallel algorithm.
When one of sub-ranges has not been move constructed into a raw buffer, we should not call clean up for that sub-range. Instead of store detailed info about raw buffer history, the fix does the cleanup a sub-range after each moving the sub-range back.
https://reviews.llvm.org/D73779
Added:
Modified:
pstl/include/pstl/internal/parallel_backend_tbb.h
Removed:
################################################################################
diff --git a/pstl/include/pstl/internal/parallel_backend_tbb.h b/pstl/include/pstl/internal/parallel_backend_tbb.h
index 244ab4c657bf..1b09ed30e838 100644
--- a/pstl/include/pstl/internal/parallel_backend_tbb.h
+++ b/pstl/include/pstl/internal/parallel_backend_tbb.h
@@ -431,7 +431,6 @@ class __merge_task : public tbb::task
_SizeType _M_ys, _M_ye;
_SizeType _M_zs;
_Compare _M_comp;
- _Cleanup _M_cleanup;
_LeafMerge _M_leaf_merge;
_SizeType _M_nsort; //number of elements to be sorted for partial_sort alforithm
@@ -440,8 +439,6 @@ class __merge_task : public tbb::task
bool _root; //means a task is merging root task
bool _x_orig; //"true" means X(or left ) subrange is in the original container; false - in the buffer
bool _y_orig; //"true" means Y(or right) subrange is in the original container; false - in the buffer
- bool _x_first_move, _y_first_move; //"true" means X and Y subranges are merging into the buffer and move constructor
- //should be called instead of just moving.
bool _split; //"true" means a merge task is a split task for parallel merging, the execution logic
diff ers
bool
@@ -512,13 +509,32 @@ class __merge_task : public tbb::task
}
};
+ struct __cleanup_range
+ {
+ template <typename Iterator>
+ void
+ operator()(Iterator __first, Iterator __last)
+ {
+ if (__last - __first < __merge_cut_off)
+ _Cleanup()(__first, __last);
+ else
+ {
+ auto __n = __last - __first;
+ tbb::parallel_for(tbb::blocked_range<_SizeType>(0, __n, __merge_cut_off),
+ [__first](const tbb::blocked_range<_SizeType>& __range) {
+ _Cleanup()(__first + __range.begin(), __first + __range.end());
+ });
+ }
+ }
+ };
+
public:
__merge_task(_SizeType __xs, _SizeType __xe, _SizeType __ys, _SizeType __ye, _SizeType __zs, _Compare __comp,
- _Cleanup __cleanup, _LeafMerge __leaf_merge, _SizeType __nsort, _RandomAccessIterator1 __x_beg,
+ _Cleanup, _LeafMerge __leaf_merge, _SizeType __nsort, _RandomAccessIterator1 __x_beg,
_RandomAccessIterator2 __z_beg, bool __x_orig, bool __y_orig, bool __root)
: _M_xs(__xs), _M_xe(__xe), _M_ys(__ys), _M_ye(__ye), _M_zs(__zs), _M_x_beg(__x_beg), _M_z_beg(__z_beg),
- _M_comp(__comp), _M_cleanup(__cleanup), _M_leaf_merge(__leaf_merge), _M_nsort(__nsort), _root(__root),
- _x_orig(__x_orig), _y_orig(__y_orig), _x_first_move(false), _y_first_move(false), _split(false)
+ _M_comp(__comp), _M_leaf_merge(__leaf_merge), _M_nsort(__nsort), _root(__root),
+ _x_orig(__x_orig), _y_orig(__y_orig), _split(false)
{
}
@@ -528,16 +544,6 @@ class __merge_task : public tbb::task
return _M_xs == __idx;
}
- template <typename IndexType>
- void
- set_first_move(IndexType __idx, bool __on_off)
- {
- if (is_left(__idx))
- _x_first_move = __on_off;
- else
- _y_first_move = __on_off;
- }
-
template <typename IndexType>
void
set_odd(IndexType __idx, bool __on_off)
@@ -584,19 +590,11 @@ class __merge_task : public tbb::task
assert(__nx > 0 && __ny > 0);
if (_x_orig)
- {
- if (_x_first_move)
- {
- move_range_construct()(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_z_beg + _M_zs);
- _x_first_move = false;
- }
- else
- move_range()(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_z_beg + _M_zs);
- }
+ __move_range_construct()(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_z_beg + _M_zs);
else
{
- assert(!_x_first_move);
- move_range()(_M_z_beg + _M_zs, _M_z_beg + _M_zs + __nx, _M_x_beg + _M_xs);
+ __move_range()(_M_z_beg + _M_zs, _M_z_beg + _M_zs + __nx, _M_x_beg + _M_xs);
+ __cleanup_range()(_M_z_beg + _M_zs, _M_z_beg + _M_zs + __nx);
}
_x_orig = !_x_orig;
@@ -608,19 +606,11 @@ class __merge_task : public tbb::task
const auto __ny = (_M_ye - _M_ys);
if (_y_orig)
- {
- if (_y_first_move)
- {
- move_range_construct()(_M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_z_beg + _M_zs + __nx);
- _y_first_move = false;
- }
- else
- move_range()(_M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_z_beg + _M_zs + __nx);
- }
+ __move_range_construct()(_M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_z_beg + _M_zs + __nx);
else
{
- assert(!_y_first_move);
- move_range()(_M_z_beg + _M_zs + __nx, _M_z_beg + _M_zs + __nx + __ny, _M_x_beg + _M_ys);
+ __move_range()(_M_z_beg + _M_zs + __nx, _M_z_beg + _M_zs + __nx + __ny, _M_x_beg + _M_ys);
+ __cleanup_range()(_M_z_beg + _M_zs + __nx, _M_z_beg + _M_zs + __nx + __ny);
}
_y_orig = !_y_orig;
@@ -641,41 +631,15 @@ class __merge_task : public tbb::task
//merge to buffer
if (_x_orig)
{
- assert(is_partial() || std::is_sorted(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_comp));
- assert(is_partial() || std::is_sorted(_M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_comp));
-
- if (_x_first_move && _y_first_move)
- {
- _M_leaf_merge(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_z_beg + _M_zs,
- _M_comp, move_value_construct(), move_value_construct(), move_range_construct(),
- move_range_construct());
- _x_first_move = false, _y_first_move = false;
- }
- else if (_x_first_move && !_y_first_move)
- {
- _M_leaf_merge(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_z_beg + _M_zs,
- _M_comp, move_value_construct(), move_value(), move_range_construct(), move_range());
- _x_first_move = false;
- }
- else if (!_x_first_move && _y_first_move)
- {
- _M_leaf_merge(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_z_beg + _M_zs,
- _M_comp, move_value(), move_value_construct(), move_range(), move_range_construct());
- _y_first_move = false;
- }
- else
- _M_leaf_merge(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_z_beg + _M_zs,
- _M_comp, move_value(), move_value(), move_range(), move_range());
-
- assert(is_partial() || std::is_sorted(_M_z_beg + _M_zs, _M_z_beg + _M_zs + __nx + __ny, _M_comp));
+ _M_leaf_merge(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_z_beg + _M_zs,
+ _M_comp, __move_value_construct(), __move_value_construct(), __move_range_construct(),
+ __move_range_construct());
assert(parent_merge()); //not root merging task
}
//merge to "origin"
else
{
assert(_x_orig == _y_orig);
- assert(!_x_first_move);
- assert(!_y_first_move);
assert(is_partial() || std::is_sorted(_M_z_beg + _M_xs, _M_z_beg + _M_xe, _M_comp));
assert(is_partial() || std::is_sorted(_M_z_beg + _M_ys, _M_z_beg + _M_ye, _M_comp));
@@ -686,17 +650,12 @@ class __merge_task : public tbb::task
_M_leaf_merge(_M_z_beg + _M_xs, _M_z_beg + _M_xe, _M_z_beg + _M_ys, _M_z_beg + _M_ye, _M_x_beg + _M_zs,
_M_comp, move_value(), move_value(), move_range(), move_range());
- assert(is_partial() || std::is_sorted(_M_x_beg + _M_zs, _M_x_beg + _M_zs + __nx + __ny, _M_comp));
-
- //in case of the root merge task - clean the buffer
- if (!parent_merge())
- {
- _M_cleanup(_M_z_beg + _M_xs, _M_z_beg + _M_xe);
- _M_cleanup(_M_z_beg + _M_ys, _M_z_beg + _M_ye);
- }
+ __cleanup_range()(_M_z_beg + _M_xs, _M_z_beg + _M_xe);
+ __cleanup_range()(_M_z_beg + _M_ys, _M_z_beg + _M_ye);
}
return nullptr;
}
+
tbb::task*
process_ranges()
{
@@ -705,49 +664,41 @@ class __merge_task : public tbb::task
auto p = parent_merge();
- //optimization, just for sort algorithm, not for partial_sort
- //{x} <= {y}
- if (!is_partial() && x_less_y())
- {
- if (p)
+ if (!p)
+ { //root merging task
+
+ //optimization, just for sort algorithm, //{x} <= {y}
+ if (!is_partial() && x_less_y()) //we have a solution
{
- const auto id_range = _M_zs;
- p->set_odd(id_range, _x_orig);
- p->set_first_move(id_range, _x_first_move);
+ if (!_x_orig)
+ { //we have to move the solution to the origin
+ move_x_range(); //parallel moving
+ move_y_range(); //parallel moving
+ }
+ return nullptr;
}
- else
- { //root task
-
- //clean the buffer
- if (!_x_first_move)
- _M_cleanup(_M_z_beg + _M_xs, _M_z_beg + _M_xe);
-
- if (!_y_first_move)
- _M_cleanup(_M_z_beg + _M_ys, _M_z_beg + _M_ye);
+ //else: if we have data in the origin,
+ //we have to move data to the buffer for final merging into the origin.
+ if (_x_orig)
+ {
+ move_x_range(); //parallel moving
+ move_y_range(); //parallel moving
}
- return nullptr;
- }
-
- //in case of the root merge task - move to the buffer firstly
- //the root merging task
- if (!p && _x_orig)
- {
- assert(_y_orig);
-
- move_x_range();
- move_y_range();
+ // need to merge {x} and {y}.
+ return merge_ranges();
}
-
- //we have to revert "_x(y)_orig" flag of the parent merging task
- if (p)
+ //else: not root merging task (parent_merge() == NULL)
+ //optimization, just for sort algorithm, //{x} <= {y}
+ if (!is_partial() && x_less_y())
{
const auto id_range = _M_zs;
- p->set_odd(id_range, !_x_orig);
+ p->set_odd(id_range, _x_orig);
+ return nullptr;
}
+ //else: we have to revert "_x(y)_orig" flag of the parent merging task
+ const auto id_range = _M_zs;
+ p->set_odd(id_range, !_x_orig);
- const _SizeType __n = (_M_xe - _M_xs) + (_M_ye - _M_ys);
-
- // need to merge {x} and {y}
return merge_ranges();
}
@@ -783,11 +734,9 @@ class __merge_task : public tbb::task
auto __zm = _M_zs + ((__xm - _M_xs) + (__ym - _M_ys));
__merge_task* __right = new (tbb::task::allocate_additional_child_of(*parent()))
- __merge_task(__xm, _M_xe, __ym, _M_ye, __zm, _M_comp, _M_cleanup, _M_leaf_merge, _M_nsort, _M_x_beg,
+ __merge_task(__xm, _M_xe, __ym, _M_ye, __zm, _M_comp, _Cleanup(), _M_leaf_merge, _M_nsort, _M_x_beg,
_M_z_beg, _x_orig, _y_orig, _root);
- __right->_x_first_move = _x_first_move;
- __right->_y_first_move = _y_first_move;
__right->_split = true;
tbb::task::spawn(*__right);
@@ -891,7 +840,6 @@ __stable_sort_task<_RandomAccessIterator1, _RandomAccessIterator2, _Compare, _Le
tbb::task* p = parent();
const auto id_range = _M_xs - _M_x_beg;
- static_cast<_MergeTaskType*>(p)->set_first_move(id_range, true);
return nullptr;
}
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