lib/rbtree_test.c: support rb_root_cached

We can work with a single rb_root_cached root to test both cached and
non-cached rbtrees.  In addition, also add a test to measure latencies
between rb_first and its fast counterpart.

Link: http://lkml.kernel.org/r/20170719014603.19029-7-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 137 insertions, 19 deletions

diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c
index 967999ff46db..191a238e5a9d 100644
--- a/lib/rbtree_test.c
+++ b/lib/rbtree_test.c
@@ -23,14 +23,14 @@ struct test_node {
         u32 augmented;
 };
 
-static struct rb_root root = RB_ROOT;
+static struct rb_root_cached root = RB_ROOT_CACHED;
 static struct test_node *nodes = NULL;
 
 static struct rnd_state rnd;
 
-static void insert(struct test_node *node, struct rb_root *root)
+static void insert(struct test_node *node, struct rb_root_cached *root)
 {
-        struct rb_node **new = &root->rb_node, *parent = NULL;
+        struct rb_node **new = &root->rb_root.rb_node, *parent = NULL;
         u32 key = node->key;
 
         while (*new) {
@@ -42,14 +42,40 @@ static void insert(struct test_node *node, struct rb_root *root)
         }
 
         rb_link_node(&node->rb, parent, new);
-        rb_insert_color(&node->rb, root);
+        rb_insert_color(&node->rb, &root->rb_root);
 }
 
-static inline void erase(struct test_node *node, struct rb_root *root)
+static void insert_cached(struct test_node *node, struct rb_root_cached *root)
 {
-        rb_erase(&node->rb, root);
+        struct rb_node **new = &root->rb_root.rb_node, *parent = NULL;
+        u32 key = node->key;
+        bool leftmost = true;
+
+        while (*new) {
+                parent = *new;
+                if (key < rb_entry(parent, struct test_node, rb)->key)
+                        new = &parent->rb_left;
+                else {
+                        new = &parent->rb_right;
+                        leftmost = false;
+                }
+        }
+
+        rb_link_node(&node->rb, parent, new);
+        rb_insert_color_cached(&node->rb, root, leftmost);
 }
 
+static inline void erase(struct test_node *node, struct rb_root_cached *root)
+{
+        rb_erase(&node->rb, &root->rb_root);
+}
+
+static inline void erase_cached(struct test_node *node, struct rb_root_cached *root)
+{
+        rb_erase_cached(&node->rb, root);
+}
+
+
 static inline u32 augment_recompute(struct test_node *node)
 {
         u32 max = node->val, child_augmented;
@@ -71,9 +97,10 @@ static inline u32 augment_recompute(struct test_node *node)
 RB_DECLARE_CALLBACKS(static, augment_callbacks, struct test_node, rb,
                      u32, augmented, augment_recompute)
 
-static void insert_augmented(struct test_node *node, struct rb_root *root)
+static void insert_augmented(struct test_node *node,
+                             struct rb_root_cached *root)
 {
-        struct rb_node **new = &root->rb_node, *rb_parent = NULL;
+        struct rb_node **new = &root->rb_root.rb_node, *rb_parent = NULL;
         u32 key = node->key;
         u32 val = node->val;
         struct test_node *parent;
@@ -91,12 +118,47 @@ static void insert_augmented(struct test_node *node, struct rb_root *root)
 
         node->augmented = val;
         rb_link_node(&node->rb, rb_parent, new);
-        rb_insert_augmented(&node->rb, root, &augment_callbacks);
+        rb_insert_augmented(&node->rb, &root->rb_root, &augment_callbacks);
+}
+
+static void insert_augmented_cached(struct test_node *node,
+                                    struct rb_root_cached *root)
+{
+        struct rb_node **new = &root->rb_root.rb_node, *rb_parent = NULL;
+        u32 key = node->key;
+        u32 val = node->val;
+        struct test_node *parent;
+        bool leftmost = true;
+
+        while (*new) {
+                rb_parent = *new;
+                parent = rb_entry(rb_parent, struct test_node, rb);
+                if (parent->augmented < val)
+                        parent->augmented = val;
+                if (key < parent->key)
+                        new = &parent->rb.rb_left;
+                else {
+                        new = &parent->rb.rb_right;
+                        leftmost = false;
+                }
+        }
+
+        node->augmented = val;
+        rb_link_node(&node->rb, rb_parent, new);
+        rb_insert_augmented_cached(&node->rb, root,
+                                   leftmost, &augment_callbacks);
+}
+
+
+static void erase_augmented(struct test_node *node, struct rb_root_cached *root)
+{
+        rb_erase_augmented(&node->rb, &root->rb_root, &augment_callbacks);
 }
 
-static void erase_augmented(struct test_node *node, struct rb_root *root)
+static void erase_augmented_cached(struct test_node *node,
+                                   struct rb_root_cached *root)
 {
-        rb_erase_augmented(&node->rb, root, &augment_callbacks);
+        rb_erase_augmented_cached(&node->rb, root, &augment_callbacks);
 }
 
 static void init(void)
@@ -125,7 +187,7 @@ static void check_postorder_foreach(int nr_nodes)
 {
         struct test_node *cur, *n;
         int count = 0;
-        rbtree_postorder_for_each_entry_safe(cur, n, &root, rb)
+        rbtree_postorder_for_each_entry_safe(cur, n, &root.rb_root, rb)
                 count++;
 
         WARN_ON_ONCE(count != nr_nodes);
@@ -135,7 +197,7 @@ static void check_postorder(int nr_nodes)
 {
         struct rb_node *rb;
         int count = 0;
-        for (rb = rb_first_postorder(&root); rb; rb = rb_next_postorder(rb))
+        for (rb = rb_first_postorder(&root.rb_root); rb; rb = rb_next_postorder(rb))
                 count++;
 
         WARN_ON_ONCE(count != nr_nodes);
@@ -147,7 +209,7 @@ static void check(int nr_nodes)
         int count = 0, blacks = 0;
         u32 prev_key = 0;
 
-        for (rb = rb_first(&root); rb; rb = rb_next(rb)) {
+        for (rb = rb_first(&root.rb_root); rb; rb = rb_next(rb)) {
                 struct test_node *node = rb_entry(rb, struct test_node, rb);
                 WARN_ON_ONCE(node->key < prev_key);
                 WARN_ON_ONCE(is_red(rb) &&
@@ -162,7 +224,7 @@ static void check(int nr_nodes)
         }
 
         WARN_ON_ONCE(count != nr_nodes);
-        WARN_ON_ONCE(count < (1 << black_path_count(rb_last(&root))) - 1);
+        WARN_ON_ONCE(count < (1 << black_path_count(rb_last(&root.rb_root))) - 1);
 
         check_postorder(nr_nodes);
         check_postorder_foreach(nr_nodes);
@@ -173,7 +235,7 @@ static void check_augmented(int nr_nodes)
         struct rb_node *rb;
 
         check(nr_nodes);
-        for (rb = rb_first(&root); rb; rb = rb_next(rb)) {
+        for (rb = rb_first(&root.rb_root); rb; rb = rb_next(rb)) {
                 struct test_node *node = rb_entry(rb, struct test_node, rb);
                 WARN_ON_ONCE(node->augmented != augment_recompute(node));
         }
@@ -207,7 +269,24 @@ static int __init rbtree_test_init(void)
         time = time2 - time1;
 
         time = div_u64(time, perf_loops);
-        printk(" -> test 1 (latency of nnodes insert+delete): %llu cycles\n", (unsigned long long)time);
+        printk(" -> test 1 (latency of nnodes insert+delete): %llu cycles\n",
+               (unsigned long long)time);
+
+        time1 = get_cycles();
+
+        for (i = 0; i < perf_loops; i++) {
+                for (j = 0; j < nnodes; j++)
+                        insert_cached(nodes + j, &root);
+                for (j = 0; j < nnodes; j++)
+                        erase_cached(nodes + j, &root);
+        }
+
+        time2 = get_cycles();
+        time = time2 - time1;
+
+        time = div_u64(time, perf_loops);
+        printk(" -> test 2 (latency of nnodes cached insert+delete): %llu cycles\n",
+               (unsigned long long)time);
 
         for (i = 0; i < nnodes; i++)
                 insert(nodes + i, &root);
@@ -215,7 +294,7 @@ static int __init rbtree_test_init(void)
         time1 = get_cycles();
 
         for (i = 0; i < perf_loops; i++) {
-                for (node = rb_first(&root); node; node = rb_next(node))
+                for (node = rb_first(&root.rb_root); node; node = rb_next(node))
                         ;
         }
 
@@ -223,7 +302,31 @@ static int __init rbtree_test_init(void)
         time = time2 - time1;
 
         time = div_u64(time, perf_loops);
-        printk(" -> test 2 (latency of inorder traversal): %llu cycles\n", (unsigned long long)time);
+        printk(" -> test 3 (latency of inorder traversal): %llu cycles\n",
+               (unsigned long long)time);
+
+        time1 = get_cycles();
+
+        for (i = 0; i < perf_loops; i++)
+                node = rb_first(&root.rb_root);
+
+        time2 = get_cycles();
+        time = time2 - time1;
+
+        time = div_u64(time, perf_loops);
+        printk(" -> test 4 (latency to fetch first node)\n");
+        printk("        non-cached: %llu cycles\n", (unsigned long long)time);
+
+        time1 = get_cycles();
+
+        for (i = 0; i < perf_loops; i++)
+                node = rb_first_cached(&root);
+
+        time2 = get_cycles();
+        time = time2 - time1;
+
+        time = div_u64(time, perf_loops);
+        printk("        cached: %llu cycles\n", (unsigned long long)time);
 
         for (i = 0; i < nnodes; i++)
                 erase(nodes + i, &root);
@@ -261,6 +364,21 @@ static int __init rbtree_test_init(void)
         time = div_u64(time, perf_loops);
         printk(" -> test 1 (latency of nnodes insert+delete): %llu cycles\n", (unsigned long long)time);
 
+        time1 = get_cycles();
+
+        for (i = 0; i < perf_loops; i++) {
+                for (j = 0; j < nnodes; j++)
+                        insert_augmented_cached(nodes + j, &root);
+                for (j = 0; j < nnodes; j++)
+                        erase_augmented_cached(nodes + j, &root);
+        }
+
+        time2 = get_cycles();
+        time = time2 - time1;
+
+        time = div_u64(time, perf_loops);
+        printk(" -> test 2 (latency of nnodes cached insert+delete): %llu cycles\n", (unsigned long long)time);
+
         for (i = 0; i < check_loops; i++) {
                 init();
                 for (j = 0; j < nnodes; j++) {