linux-kernel - [PATCH 3/7] perf callchain: Use cached rbtrees

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Date:   Sun, 26 Nov 2017 18:30:42 -0800
From:   Davidlohr Bueso <dave@...olabs.net>
To:     acme@...nel.org
Cc:     jolsa@...hat.com, ak@...ux.intel.com, mingo@...hat.com,
        dave@...olabs.net, linux-kernel@...r.kernel.org,
        Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 3/7] perf callchain: Use cached rbtrees

At the cost of an extra pointer, we can avoid the O(logN) cost
of finding the first element in the tree (smallest node), which
is something required for nearly every srcline callchain node
deletion (srcline__tree_delete()).

Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 tools/perf/util/dso.c     |  2 +-
 tools/perf/util/dso.h     |  2 +-
 tools/perf/util/srcline.c | 21 ++++++++++++---------
 tools/perf/util/srcline.h |  6 +++---
 4 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index d5b6f7f5baff..7b1f56a6d3fd 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1204,7 +1204,7 @@ struct dso *dso__new(const char *name)
 			dso->symbols[i] = dso->symbol_names[i] = RB_ROOT;
 		dso->data.cache = RB_ROOT;
 		dso->inlined_nodes = RB_ROOT;
-		dso->srclines = RB_ROOT;
+		dso->srclines = RB_ROOT_CACHED;
 		dso->data.fd = -1;
 		dso->data.status = DSO_DATA_STATUS_UNKNOWN;
 		dso->symtab_type = DSO_BINARY_TYPE__NOT_FOUND;
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index c229dbe0277a..620b38d763d9 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -143,7 +143,7 @@ struct dso {
 	struct rb_root	 symbols[MAP__NR_TYPES];
 	struct rb_root	 symbol_names[MAP__NR_TYPES];
 	struct rb_root	 inlined_nodes;
-	struct rb_root	 srclines;
+	struct rb_root_cached srclines;
 	struct {
 		u64		addr;
 		struct symbol	*symbol;
diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
index d19f05c56de6..e34b23e450a0 100644
--- a/tools/perf/util/srcline.c
+++ b/tools/perf/util/srcline.c
@@ -561,11 +561,12 @@ struct srcline_node {
 	struct rb_node		rb_node;
 };
 
-void srcline__tree_insert(struct rb_root *tree, u64 addr, char *srcline)
+void srcline__tree_insert(struct rb_root_cached *tree, u64 addr, char *srcline)
 {
-	struct rb_node **p = &tree->rb_node;
+	struct rb_node **p = &tree->rb_root.rb_node;
 	struct rb_node *parent = NULL;
 	struct srcline_node *i, *node;
+	bool leftmost = true;
 
 	node = zalloc(sizeof(struct srcline_node));
 	if (!node) {
@@ -581,16 +582,18 @@ void srcline__tree_insert(struct rb_root *tree, u64 addr, char *srcline)
 		i = rb_entry(parent, struct srcline_node, rb_node);
 		if (addr < i->addr)
 			p = &(*p)->rb_left;
-		else
+		else {
 			p = &(*p)->rb_right;
+			leftmost = false;
+		}
 	}
 	rb_link_node(&node->rb_node, parent, p);
-	rb_insert_color(&node->rb_node, tree);
+	rb_insert_color_cached(&node->rb_node, tree, leftmost);
 }
 
-char *srcline__tree_find(struct rb_root *tree, u64 addr)
+char *srcline__tree_find(struct rb_root_cached *tree, u64 addr)
 {
-	struct rb_node *n = tree->rb_node;
+	struct rb_node *n = tree->rb_root.rb_node;
 
 	while (n) {
 		struct srcline_node *i = rb_entry(n, struct srcline_node,
@@ -607,15 +610,15 @@ char *srcline__tree_find(struct rb_root *tree, u64 addr)
 	return NULL;
 }
 
-void srcline__tree_delete(struct rb_root *tree)
+void srcline__tree_delete(struct rb_root_cached *tree)
 {
 	struct srcline_node *pos;
-	struct rb_node *next = rb_first(tree);
+	struct rb_node *next = rb_first_cached(tree);
 
 	while (next) {
 		pos = rb_entry(next, struct srcline_node, rb_node);
 		next = rb_next(&pos->rb_node);
-		rb_erase(&pos->rb_node, tree);
+		rb_erase_cached(&pos->rb_node, tree);
 		free_srcline(pos->srcline);
 		zfree(&pos);
 	}
diff --git a/tools/perf/util/srcline.h b/tools/perf/util/srcline.h
index 847b7086182c..58e75a06f699 100644
--- a/tools/perf/util/srcline.h
+++ b/tools/perf/util/srcline.h
@@ -17,11 +17,11 @@ char *__get_srcline(struct dso *dso, u64 addr, struct symbol *sym,
 void free_srcline(char *srcline);
 
 /* insert the srcline into the DSO, which will take ownership */
-void srcline__tree_insert(struct rb_root *tree, u64 addr, char *srcline);
+void srcline__tree_insert(struct rb_root_cached *tree, u64 addr, char *srcline);
 /* find previously inserted srcline */
-char *srcline__tree_find(struct rb_root *tree, u64 addr);
+char *srcline__tree_find(struct rb_root_cached *tree, u64 addr);
 /* delete all srclines within the tree */
-void srcline__tree_delete(struct rb_root *tree);
+void srcline__tree_delete(struct rb_root_cached *tree);
 
 #define SRCLINE_UNKNOWN  ((char *) "??:0")
 
-- 
2.13.6