[PATCH RFC 3/6] maple_tree: use percpu sheaves for maple_node_cache

[Vlastimil Babka]

Setup the maple_node_cache with percpu sheaves of size 32 to hopefully
improve its performance. Change the single node rcu freeing in
ma_free_rcu() to use kfree_rcu() instead of the custom callback, which
allows the rcu_free sheaf batching to be used. Note there are other
users of mt_free_rcu() where larger parts of maple tree are submitted to
call_rcu() as a whole, and that cannot use the rcu_free sheaf, but it's
still possible for maple nodes freed this way to be reused via the barn,
even if only some cpus are allowed to process rcu callbacks.

Signed-off-by: Vlastimil Babka <vbabka at suse.cz>
---
 lib/maple_tree.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 3619301dda2ebeaaba8a73837389b6ee3c7e1a3f..c69365e17fcbfe963dcedd0de07335fc6bbdfb27 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -194,7 +194,7 @@ static void mt_free_rcu(struct rcu_head *head)
 static void ma_free_rcu(struct maple_node *node)
 {
 	WARN_ON(node->parent != ma_parent_ptr(node));
-	call_rcu(&node->rcu, mt_free_rcu);
+	kfree_rcu(node, rcu);
 }
 
 static void mas_set_height(struct ma_state *mas)
@@ -6299,9 +6299,14 @@ bool mas_nomem(struct ma_state *mas, gfp_t gfp)
 
 void __init maple_tree_init(void)
 {
+	struct kmem_cache_args args = {
+		.align  = sizeof(struct maple_node),
+		.sheaf_capacity = 32,
+	};
+
 	maple_node_cache = kmem_cache_create("maple_node",
-			sizeof(struct maple_node), sizeof(struct maple_node),
-			SLAB_PANIC, NULL);
+			sizeof(struct maple_node), &args,
+			SLAB_PANIC);
 }
 
 /**

-- 
2.47.0