diff options
| author | Sidhartha Kumar <sidhartha.kumar@oracle.com> | 2025-04-10 19:14:43 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-05-11 17:48:28 -0700 |
| commit | ad88fc17d2dafe45e40de2af80207f4b2e3b1f71 (patch) | |
| tree | b43b6ba4810fcaf2cd12980b95c6d78731fbd0d5 /include | |
| parent | maple_tree: use height and depth consistently (diff) | |
| download | linux-ad88fc17d2dafe45e40de2af80207f4b2e3b1f71.tar.gz linux-ad88fc17d2dafe45e40de2af80207f4b2e3b1f71.zip | |
maple_tree: use vacant nodes to reduce worst case allocations
In order to determine the store type for a maple tree operation, a walk of
the tree is done through mas_wr_walk(). This function descends the tree
until a spanning write is detected or we reach a leaf node. While
descending, keep track of the height at which we encounter a node with
available space. This is done by checking if mas->end is less than the
number of slots a given node type can fit.
Now that the height of the vacant node is tracked, we can use the
difference between the height of the tree and the height of the vacant
node to know how many levels we will have to propagate creating new nodes.
Update mas_prealloc_calc() to consider the vacant height and reduce the
number of worst-case allocations.
Rebalancing and spanning stores are not supported and fall back to using
the full height of the tree for allocations.
Update preallocation testing assertions to take into account vacant
height.
Link: https://lkml.kernel.org/r/20250410191446.2474640-4-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/maple_tree.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h index cbbcd18d4186..657adb33e61e 100644 --- a/include/linux/maple_tree.h +++ b/include/linux/maple_tree.h @@ -463,6 +463,7 @@ struct ma_wr_state { void __rcu **slots; /* mas->node->slots pointer */ void *entry; /* The entry to write */ void *content; /* The existing entry that is being overwritten */ + unsigned char vacant_height; /* Height of lowest node with free space */ }; #define mas_lock(mas) spin_lock(&((mas)->tree->ma_lock)) @@ -498,6 +499,7 @@ struct ma_wr_state { .mas = ma_state, \ .content = NULL, \ .entry = wr_entry, \ + .vacant_height = 0 \ } #define MA_TOPIARY(name, tree) \ |