+ maple_tree-mtree_range_walk-clean-up.patch added to mm-unstable branch

+ maple_tree-mtree_range_walk-clean-up.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: maple_tree: mtree_range_walk() clean up
has been added to the -mm mm-unstable branch.  Its filename is
     maple_tree-mtree_range_walk-clean-up.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-mtree_range_walk-clean-up.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Subject: maple_tree: mtree_range_walk() clean up
Date: Wed, 1 Nov 2023 13:16:29 -0400

mtree_range_walk() needed to be updated to avoid checking if there was a
pivot value.  On closer examination, the code could avoid setting min or
max in certain scenarios.  The commit removes the extra check for
pivot[offset] before setting max and only sets max when necessary.  It
also only sets min if it is necessary by checking offset 0 prior to the
loop (as it has always done).

The commit also drops a dead node check since the end of the node will
return the array size when the last slot is occupied (by a potential reuse
in a dead node).  The data will be discarded later if the node is marked
dead.

Benchmarking these changes results in an increase in performance of 5.45%
using the BENCH_WALK in the maple tree test code.

Link: https://lkml.kernel.org/r/20231101171629.3612299-13-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/maple_tree.c |   27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

--- a/lib/maple_tree.c~maple_tree-mtree_range_walk-clean-up
+++ a/lib/maple_tree.c
@@ -2806,32 +2806,29 @@ static inline void *mtree_range_walk(str
 	min = mas->min;
 	max = mas->max;
 	do {
-		offset = 0;
 		last = next;
 		node = mte_to_node(next);
 		type = mte_node_type(next);
 		pivots = ma_pivots(node, type);
 		end = ma_data_end(node, type, pivots, max);
-		if (unlikely(ma_dead_node(node)))
-			goto dead_node;
-
-		if (pivots[offset] >= mas->index) {
-			prev_max = max;
-			prev_min = min;
-			max = pivots[offset];
+		prev_min = min;
+		prev_max = max;
+		if (pivots[0] >= mas->index) {
+			offset = 0;
+			max = pivots[0];
 			goto next;
 		}
 
-		do {
+		offset = 1;
+		while (offset < end) {
+			if (pivots[offset] >= mas->index) {
+				max = pivots[offset];
+				break;
+			}
 			offset++;
-		} while ((offset < end) && (pivots[offset] < mas->index));
+		}
 
-		prev_min = min;
 		min = pivots[offset - 1] + 1;
-		prev_max = max;
-		if (likely(offset < end && pivots[offset]))
-			max = pivots[offset];
-
 next:
 		slots = ma_slots(node, type);
 		next = mt_slot(mas->tree, slots, offset);
_

Patches currently in -mm which might be from Liam.Howlett@oracle.com are

maple_tree-remove-unnecessary-default-labels-from-switch-statements.patch
maple_tree-make-mas_erase-more-robust.patch
maple_tree-move-debug-check-to-__mas_set_range.patch
maple_tree-add-end-of-node-tracking-to-the-maple-state.patch
maple_tree-use-cached-node-end-in-mas_next.patch
maple_tree-use-cached-node-end-in-mas_destroy.patch
maple_tree-clean-up-inlines-for-some-functions.patch
maple_tree-separate-ma_state-node-from-status.patch
maple_tree-separate-ma_state-node-from-status-fix-1.patch
maple_tree-separate-ma_state-node-from-status-fix-2.patch
maple_tree-remove-mas_searchable.patch
maple_tree-use-maple-state-end-for-write-operations.patch
maple_tree-dont-find-node-end-in-mtree_lookup_walk.patch
maple_tree-mtree_range_walk-clean-up.patch