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FROMGIT: 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>

(cherry picked from commit 0f4e7f5fc2122534ae0573b37224ddfa367fa7ac
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm mm-unstable)

Bug: 274059236
Change-Id: I4a5e852906692b27ea598fdf38eba8e1a69355d9
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Liam R. Howlett 2023-05-18 10:55:12 -04:00 committed by Suren Baghdasaryan
parent e9fdabfc2a
commit c3118993c9
2 changed files with 12 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
lib/maple_tree.c
View File

@ -1101,7 +1101,6 @@ 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);
@ -1113,8 +1112,9 @@ 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_enum(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 */
@ -1122,7 +1122,6 @@ 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;
@ -1130,6 +1129,12 @@ 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

@ -35234,6 +35234,7 @@ 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);
@ -35266,6 +35267,9 @@ static void mas_dfs_preorder(struct ma_state *mas)
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: