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maple_tree: avoid unnecessary ascending

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The maple tree node limits are implied by the parent.  When walking up the
tree, the limit may not be known until a slot that does not have implied
limits are encountered.  However, if the node is the left-most or
right-most node, the walking up to find that limit can be skipped.

This commit also fixes the debug/testing code that was not setting the
limit on walking down the tree as that optimization is not compatible with
this change.

Link: https://lkml.kernel.org/r/20230518145544.1722059-4-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: David Binderman <dcb314@hotmail.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Vernon Yang <vernon2gm@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liam R. Howlett 2023-05-18 10:55:12 -04:00 committed by Andrew Morton
parent afc754c651
commit 633769c926
2 changed files with 12 additions and 3 deletions
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11
lib/maple_tree.c
View File

@ -1103,7 +1103,6 @@ static int mas_ascend(struct ma_state *mas)
enum maple_type a_type;
unsigned long min, max;
unsigned long *pivots;
unsigned char offset;
bool set_max = false, set_min = false;
a_node = mas_mn(mas);
@ -1115,8 +1114,9 @@ static int mas_ascend(struct ma_state *mas)
p_node = mte_parent(mas->node);
if (unlikely(a_node == p_node))
return 1;
a_type = mas_parent_type(mas, mas->node);
offset = mte_parent_slot(mas->node);
mas->offset = mte_parent_slot(mas->node);
a_enode = mt_mk_node(p_node, a_type);
/* Check to make sure all parent information is still accurate */
@ -1124,7 +1124,6 @@ static int mas_ascend(struct ma_state *mas)
return 1;
mas->node = a_enode;
mas->offset = offset;
if (mte_is_root(a_enode)) {
mas->max = ULONG_MAX;
@ -1132,6 +1131,12 @@ static int mas_ascend(struct ma_state *mas)
return 0;
}
if (!mas->min)
set_min = true;
if (mas->max == ULONG_MAX)
set_max = true;
min = 0;
max = ULONG_MAX;
do {

4
tools/testing/radix-tree/maple.c
View File

@ -35259,6 +35259,7 @@ static void mas_dfs_preorder(struct ma_state *mas)
struct maple_enode *prev;
unsigned char end, slot = 0;
unsigned long *pivots;
if (mas->node == MAS_START) {
mas_start(mas);
@ -35291,6 +35292,9 @@ walk_up:
mas_ascend(mas);
goto walk_up;
}
pivots = ma_pivots(mte_to_node(prev), mte_node_type(prev));
mas->max = mas_safe_pivot(mas, pivots, slot, mte_node_type(prev));
mas->min = mas_safe_min(mas, pivots, slot);
return;
done: