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maple_tree: avoid extra gap calculation

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Prior to ending the ascension loop of larger operations like split,
rebalance, and spanning store the gap in the node had been calculated. 
Once the node is inserted into the tree, the gap is recalculated in
mas_update_gap().  This can be avoided by creating a helper for
mas_update_gap() that accepts the known gap value, which reduces the
operations required for gap updating path.

Link: https://lore.kernel.org/20260821192627.4085470-19-liam@infradead.org
Signed-off-by: Liam R. Howlett (Oracle) <liam@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Chris Mason <clm@meta.com>
Cc: Chuck Lever <cel@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joe Perches <joe@perches.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liam R. Howlett (Oracle)
2026-08-21 15:26:26 -04:00
committed by Andrew Morton
parent 00f67814a1
commit 4e4fe9d727
1 changed files with 17 additions and 11 deletions
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28
lib/maple_tree.c
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@@ -1566,14 +1566,26 @@ static inline void mas_parent_gap(struct ma_state *mas, unsigned char offset,
goto ascend;
}
static __always_inline void mas_update_gap_known(struct ma_state *mas,
unsigned long gap)
{
unsigned char pslot;
unsigned long p_gap;
pslot = mte_parent_slot(mas->node);
p_gap = ma_gaps(mte_parent(mas->node),
mas_parent_type(mas, mas->node))[pslot];
if (p_gap != gap)
mas_parent_gap(mas, pslot, gap);
}
/*
* mas_update_gap() - Update a nodes gaps and propagate up if necessary.
* @mas: the maple state.
*/
static inline void mas_update_gap(struct ma_state *mas)
{
unsigned char pslot;
unsigned long p_gap;
unsigned long max_gap;
if (!mt_is_alloc(mas->tree))
@@ -1583,13 +1595,7 @@ static inline void mas_update_gap(struct ma_state *mas)
return;
max_gap = mas_max_gap(mas);
pslot = mte_parent_slot(mas->node);
p_gap = ma_gaps(mte_parent(mas->node),
mas_parent_type(mas, mas->node))[pslot];
if (p_gap != max_gap)
mas_parent_gap(mas, pslot, max_gap);
mas_update_gap_known(mas, max_gap);
}
/*
@@ -2137,8 +2143,8 @@ static inline void mas_wmb_replace(struct ma_state *mas, struct maple_copy *cp)
mas->node = mt_slot_locked(mas->tree, cp->slot, 0);
/* Insert the new data in the tree */
mas_topiary_replace(mas, old_enode, cp->height);
if (!mte_is_leaf(mas->node))
mas_update_gap(mas);
if (mt_is_alloc(mas->tree) && !mte_is_root(mas->node))
mas_update_gap_known(mas, cp->gap[0]);
mtree_range_walk(mas);
}