The patch titled
Subject: maple_tree: break on convergence in mas_spanning_rebalance()
has been added to the -mm mm-unstable branch. Its filename is
maple_tree-break-on-convergence-in-mas_spanning_rebalance.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-break-on-convergence-in-mas_spanning_rebalance.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: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Subject: maple_tree: break on convergence in mas_spanning_rebalance()
Date: Thu, 27 Feb 2025 20:48:21 +0000
This allows support for using the vacant height to calculate the worst
case number of nodes needed for wr_rebalance operation.
mas_spanning_rebalance() was seen to perform unnecessary node allocations.
We can reduce allocations by breaking early during the rebalancing loop
once we realize that we have ascended to a common ancestor.
Link: https://lkml.kernel.org/r/20250227204823.758784-5-sidhartha.kumar@xxxxxxxxxx
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Suggested-by: Liam Howlett <liam.howlett@xxxxxxxxxx>
Reviewed-by: Wei Yang <richard.weiyang@xxxxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/maple_tree.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
--- a/lib/maple_tree.c~maple_tree-break-on-convergence-in-mas_spanning_rebalance
+++ a/lib/maple_tree.c
@@ -2895,11 +2895,24 @@ static void mas_spanning_rebalance(struc
mast_combine_cp_right(mast);
mast->orig_l->last = mast->orig_l->max;
- if (mast_sufficient(mast))
- continue;
+ if (mast_sufficient(mast)) {
+ if (mast_overflow(mast))
+ continue;
+
+ if (mast->orig_l->node == mast->orig_r->node) {
+ /*
+ * The data in b_node should be stored in one
+ * node and in the tree
+ */
+ slot = mast->l->offset;
+ /* May be a new root stored in mast->bn */
+ if (mas_is_root_limits(mast->orig_l))
+ new_height++;
+ break;
+ }
- if (mast_overflow(mast))
continue;
+ }
/* May be a new root stored in mast->bn */
if (mas_is_root_limits(mast->orig_l)) {
_
Patches currently in -mm which might be from sidhartha.kumar@xxxxxxxxxx are
maple_tree-convert-mas_prealloc_calc-to-take-in-a-maple-write-state.patch
maple_tree-use-height-and-depth-consistently.patch
maple_tree-use-vacant-nodes-to-reduce-worst-case-allocations.patch
maple_tree-break-on-convergence-in-mas_spanning_rebalance.patch
maple_tree-add-sufficient-height.patch
maple_tree-reorder-mas-store_type-case-statements.patch
