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Message-ID: <20120713231134.GA3269@google.com>
Date: Fri, 13 Jul 2012 16:11:34 -0700
From: Michel Lespinasse <walken@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: aarcange@...hat.com, dwmw2@...radead.org, riel@...hat.com,
peterz@...radead.org, daniel.santos@...ox.com, axboe@...nel.dk,
ebiederm@...ssion.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org
Subject: [PATCH v2 05/12] rbtree: performance and correctness test
This small module helps measure the performance of rbtree insert and erase.
Additionally, we run a few correctness tests to check that the rbtrees have
all desired properties:
- contains the right number of nodes in the order desired,
- never two consecutive red nodes on any path,
- all paths to leaf nodes have the same number of black nodes,
- root node is black
Signed-off-by: Michel Lespinasse <walken@...gle.com>
---
lib/Kconfig.debug | 7 +++
lib/Makefile | 2 +
lib/rbtree_test.c | 135 +++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 144 insertions(+), 0 deletions(-)
create mode 100644 lib/rbtree_test.c
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 6777153..736f564 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1145,6 +1145,13 @@ config LATENCYTOP
source mm/Kconfig.debug
source kernel/trace/Kconfig
+config RBTREE_TEST
+ tristate "Red-Black tree test"
+ depends on m && DEBUG_KERNEL
+ help
+ A benchmark measuring the performance of the rbtree library.
+ Also includes rbtree invariant checks.
+
config PROVIDE_OHCI1394_DMA_INIT
bool "Remote debugging over FireWire early on boot"
depends on PCI && X86
diff --git a/lib/Makefile b/lib/Makefile
index 18515f0..4899899 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -123,6 +123,8 @@ obj-$(CONFIG_SIGNATURE) += digsig.o
obj-$(CONFIG_CLZ_TAB) += clz_tab.o
+obj-$(CONFIG_RBTREE_TEST) += rbtree_test.o
+
hostprogs-y := gen_crc32table
clean-files := crc32table.h
diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c
new file mode 100644
index 0000000..4c6d250
--- /dev/null
+++ b/lib/rbtree_test.c
@@ -0,0 +1,135 @@
+#include <linux/module.h>
+#include <linux/rbtree.h>
+#include <linux/random.h>
+#include <asm/timex.h>
+
+#define NODES 100
+#define PERF_LOOPS 100000
+#define CHECK_LOOPS 100
+
+struct test_node {
+ struct rb_node rb;
+ u32 key;
+};
+
+static struct rb_root root = RB_ROOT;
+static struct test_node nodes[NODES];
+
+static struct rnd_state rnd;
+
+static void insert(struct test_node *node, struct rb_root *root)
+{
+ struct rb_node **new = &root->rb_node, *parent = NULL;
+
+ while (*new) {
+ parent = *new;
+ if (node->key < rb_entry(parent, struct test_node, rb)->key)
+ new = &parent->rb_left;
+ else
+ new = &parent->rb_right;
+ }
+
+ rb_link_node(&node->rb, parent, new);
+ rb_insert_color(&node->rb, root);
+}
+
+static inline void erase(struct test_node *node, struct rb_root *root)
+{
+ rb_erase(&node->rb, root);
+}
+
+static void init(void)
+{
+ int i;
+ for (i = 0; i < NODES; i++)
+ nodes[i].key = prandom32(&rnd);
+}
+
+static bool is_red(struct rb_node *rb)
+{
+ return !(rb->__rb_parent_color & 1);
+}
+
+static int black_path_count(struct rb_node *rb)
+{
+ int count;
+ for (count = 0; rb; rb = rb_parent(rb))
+ count += !is_red(rb);
+ return count;
+}
+
+static void check(int nr_nodes)
+{
+ struct rb_node *rb;
+ int count = 0;
+ int blacks;
+ u32 prev_key = 0;
+
+ for (rb = rb_first(&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) &&
+ (!rb_parent(rb) || is_red(rb_parent(rb))));
+ if (!count)
+ blacks = black_path_count(rb);
+ else
+ WARN_ON_ONCE((!rb->rb_left || !rb->rb_right) &&
+ blacks != black_path_count(rb));
+ prev_key = node->key;
+ count++;
+ }
+ WARN_ON_ONCE(count != nr_nodes);
+}
+
+static int rbtree_test_init(void)
+{
+ int i, j;
+ cycles_t time1, time2, time;
+
+ printk(KERN_ALERT "rbtree testing");
+
+ prandom32_seed(&rnd, 3141592653589793238);
+ init();
+
+ time1 = get_cycles();
+
+ for (i = 0; i < PERF_LOOPS; i++) {
+ for (j = 0; j < NODES; j++)
+ insert(nodes + j, &root);
+ for (j = 0; j < NODES; j++)
+ erase(nodes + j, &root);
+ }
+
+ time2 = get_cycles();
+ time = time2 - time1;
+
+ time = div_u64(time, PERF_LOOPS);
+ printk(" -> %llu cycles\n", time);
+
+ for (i = 0; i < CHECK_LOOPS; i++) {
+ init();
+ for (j = 0; j < NODES; j++) {
+ check(j);
+ insert(nodes + j, &root);
+ }
+ for (j = 0; j < NODES; j++) {
+ check(NODES - j);
+ erase(nodes + j, &root);
+ }
+ check(0);
+ }
+
+ return -EAGAIN; /* Fail will directly unload the module */
+}
+
+static void rbtree_test_exit(void)
+{
+ printk(KERN_ALERT "test exit\n");
+}
+
+module_init(rbtree_test_init)
+module_exit(rbtree_test_exit)
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Michel Lespinasse");
+MODULE_DESCRIPTION("Red Black Tree test");
--
1.7.7.3
--
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