maple_tree: don't find node end in mtree_lookup_walk()

Since the pivot being set is now reliable, the optimized loop no longer
needs to find the node end.  The redundant check for a dead node can also
be avoided as there is no danger of using the wrong pivot since the
results will be thrown out in the case of a dead node by the later check.

This patch also adds a benchmark test for the function to the maple tree
test framework.  The benchmark shows an average increase performance of
5.98% over 3 runs with this commit.

Link: https://lkml.kernel.org/r/20231101171629.3612299-12-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>

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 59500fe6988ba0451efee12f01d1ea851dee1ebe..bc62122a4b15a93418baf709ee9ef09b80d9a665 100644 (file)
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -3742,23 +3742,17 @@ static inline void *mtree_lookup_walk(struct ma_state *mas)
        enum maple_type type;
        void __rcu **slots;
        unsigned char end;
-       unsigned long max;
 
        next = mas->node;
-       max = ULONG_MAX;
        do {
-               offset = 0;
                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;
+               end = mt_pivots[type];
+               offset = 0;
                do {
-                       if (pivots[offset] >= mas->index) {
-                               max = pivots[offset];
+                       if (pivots[offset] >= mas->index)
                                break;
-                       }
                } while (++offset < end);
 
                slots = ma_slots(node, type);

diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
index e7a5d688c9e0d37263ee749d1bb117f5fa2ebe77..29185ac5c727f6f14bf2bd62ed9c16c9acdca085 100644 (file)
--- a/lib/test_maple_tree.c
+++ b/lib/test_maple_tree.c
@@ -43,6 +43,7 @@ atomic_t maple_tree_tests_passed;
 /* #define BENCH_NODE_STORE */
 /* #define BENCH_AWALK */
 /* #define BENCH_WALK */
+/* #define BENCH_LOAD */
 /* #define BENCH_MT_FOR_EACH */
 /* #define BENCH_FORK */
 /* #define BENCH_MAS_FOR_EACH */
@@ -1754,6 +1755,19 @@ static noinline void __init bench_walk(struct maple_tree *mt)
 }
 #endif
 
+#if defined(BENCH_LOAD)
+static noinline void __init bench_load(struct maple_tree *mt)
+{
+       int i, max = 2500, count = 550000000;
+
+       for (i = 0; i < max; i += 10)
+               mtree_store_range(mt, i, i + 5, xa_mk_value(i), GFP_KERNEL);
+
+       for (i = 0; i < count; i++)
+               mtree_load(mt, 1470);
+}
+#endif
+
 #if defined(BENCH_MT_FOR_EACH)
 static noinline void __init bench_mt_for_each(struct maple_tree *mt)
 {
@@ -3623,6 +3637,13 @@ static int __init maple_tree_seed(void)
        mtree_destroy(&tree);
        goto skip;
 #endif
+#if defined(BENCH_LOAD)
+#define BENCH
+       mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
+       bench_load(&tree);
+       mtree_destroy(&tree);
+       goto skip;
+#endif
 #if defined(BENCH_FORK)
 #define BENCH
        bench_forking();