Commit 633769c9 authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

maple_tree: avoid unnecessary ascending 

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: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: default avatarPeng 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent afc754c6

lib/maple_tree.c

+8 −3
Original line number Original line Diff line number Diff line
@@ -1103,7 +1103,6 @@ static int mas_ascend(struct ma_state *mas) 
	enum maple_type a_type;

	enum maple_type a_type;

	unsigned long min, max;

	unsigned long min, max;

	unsigned long *pivots;

	unsigned long *pivots;

	unsigned char offset;

	bool set_max = false, set_min = false;

	bool set_max = false, set_min = false;





	a_node = mas_mn(mas);

	a_node = mas_mn(mas);
@@ -1115,8 +1114,9 @@ static int mas_ascend(struct ma_state *mas) 
	p_node = mte_parent(mas->node);

	p_node = mte_parent(mas->node);

	if (unlikely(a_node == p_node))

	if (unlikely(a_node == p_node))

		return 1;

		return 1;



	a_type = mas_parent_type(mas, mas->node);

	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);

	a_enode = mt_mk_node(p_node, a_type);





	/* Check to make sure all parent information is still accurate */

	/* Check to make sure all parent information is still accurate */
@@ -1124,7 +1124,6 @@ static int mas_ascend(struct ma_state *mas) 
		return 1;

		return 1;





	mas->node = a_enode;

	mas->node = a_enode;

	mas->offset = offset;





	if (mte_is_root(a_enode)) {

	if (mte_is_root(a_enode)) {

		mas->max = ULONG_MAX;

		mas->max = ULONG_MAX;
@@ -1132,6 +1131,12 @@ static int mas_ascend(struct ma_state *mas) 
		return 0;

		return 0;

	}

	}





	if (!mas->min)

		set_min = true;



	if (mas->max == ULONG_MAX)

		set_max = true;



	min = 0;

	min = 0;

	max = ULONG_MAX;

	max = ULONG_MAX;

	do {

	do {

tools/testing/radix-tree/maple.c

+4 −0
Original line number Original line Diff line number Diff line
@@ -35259,6 +35259,7 @@ static void mas_dfs_preorder(struct ma_state *mas) 










	struct maple_enode *prev;




	struct maple_enode *prev;








	unsigned char end, slot = 0;




	unsigned char end, slot = 0;










	unsigned long *pivots;


















	if (mas->node == MAS_START) {




	if (mas->node == MAS_START) {








		mas_start(mas);




		mas_start(mas);










@@ -35291,6 +35292,9 @@ static void mas_dfs_preorder(struct ma_state *mas)






		mas_ascend(mas);




		mas_ascend(mas);








		goto walk_up;




		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;




	return;








done:




done: