perf_counter tools: Various fixes for callchains

The symbol resolving has of course revealed some bugs in the
callchain tree handling. This patch fixes some of them,
including:

- inherit the children from the parents while splitting a node
- fix list range moving
- fix indexes setting in callchains
- create a child on the current node if the path doesn't match in
  the existent children (was only done on the root)
- compare using symbols when possible so that we can match a function
  using any ip inside by referring to its start address.

The practical effects are:

- remove double callchains
- fix upside down or any random order of callchains
- fix wrong paths
- fix bad hits and percentage accounts

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <1246419315-9968-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 90 insertions, 32 deletions

diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 6568cb198ba..440db12c635 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -4,6 +4,9 @@
  * Handle the callchains from the stream in an ad-hoc radix tree and then
  * sort them in an rbtree.
  *
+ * Using a radix for code path provides a fast retrieval and factorizes
+ * memory use. Also that lets us use the paths in a hierarchical graph view.
+ *
  */
 
 #include <stdlib.h>
@@ -14,7 +17,8 @@
 #include "callchain.h"
 
 
-static void rb_insert_callchain(struct rb_root *root, struct callchain_node *chain)
+static void
+rb_insert_callchain(struct rb_root *root, struct callchain_node *chain)
 {
         struct rb_node **p = &root->rb_node;
         struct rb_node *parent = NULL;
@@ -49,7 +53,12 @@ void sort_chain_to_rbtree(struct rb_root *rb_root, struct callchain_node *node)
                 rb_insert_callchain(rb_root, node);
 }
 
-static struct callchain_node *create_child(struct callchain_node *parent)
+/*
+ * Create a child for a parent. If inherit_children, then the new child
+ * will become the new parent of it's parent children
+ */
+static struct callchain_node *
+create_child(struct callchain_node *parent, bool inherit_children)
 {
         struct callchain_node *new;
 
@@ -61,14 +70,27 @@ static struct callchain_node *create_child(struct callchain_node *parent)
         new->parent = parent;
         INIT_LIST_HEAD(&new->children);
         INIT_LIST_HEAD(&new->val);
+
+        if (inherit_children) {
+                struct callchain_node *next;
+
+                list_splice(&parent->children, &new->children);
+                INIT_LIST_HEAD(&parent->children);
+
+                list_for_each_entry(next, &new->children, brothers)
+                        next->parent = new;
+        }
         list_add_tail(&new->brothers, &parent->children);
 
         return new;
 }
 
+/*
+ * Fill the node with callchain values
+ */
 static void
-fill_node(struct callchain_node *node, struct ip_callchain *chain, int start,
-          struct symbol **syms)
+fill_node(struct callchain_node *node, struct ip_callchain *chain,
+          int start, struct symbol **syms)
 {
         int i;
 
@@ -84,54 +106,80 @@ fill_node(struct callchain_node *node, struct ip_callchain *chain, int start,
                 call->sym = syms[i];
                 list_add_tail(&call->list, &node->val);
         }
-        node->val_nr = i - start;
+        node->val_nr = chain->nr - start;
+        if (!node->val_nr)
+                printf("Warning: empty node in callchain tree\n");
 }
 
-static void add_child(struct callchain_node *parent, struct ip_callchain *chain,
-                      struct symbol **syms)
+static void
+add_child(struct callchain_node *parent, struct ip_callchain *chain,
+          int start, struct symbol **syms)
 {
         struct callchain_node *new;
 
-        new = create_child(parent);
-        fill_node(new, chain, parent->val_nr, syms);
+        new = create_child(parent, false);
+        fill_node(new, chain, start, syms);
 
         new->hit = 1;
 }
 
+/*
+ * Split the parent in two parts (a new child is created) and
+ * give a part of its callchain to the created child.
+ * Then create another child to host the given callchain of new branch
+ */
 static void
 split_add_child(struct callchain_node *parent, struct ip_callchain *chain,
-                struct callchain_list *to_split, int idx, struct symbol **syms)
+                struct callchain_list *to_split, int idx_parents, int idx_local,
+                struct symbol **syms)
 {
         struct callchain_node *new;
+        struct list_head *old_tail;
+        int idx_total = idx_parents + idx_local;
 
         /* split */
-        new = create_child(parent);
-        list_move_tail(&to_split->list, &new->val);
-        new->hit = parent->hit;
-        parent->hit = 0;
-        parent->val_nr = idx;
+        new = create_child(parent, true);
+
+        /* split the callchain and move a part to the new child */
+        old_tail = parent->val.prev;
+        list_del_range(&to_split->list, old_tail);
+        new->val.next = &to_split->list;
+        new->val.prev = old_tail;
+        to_split->list.prev = &new->val;
+        old_tail->next = &new->val;
 
-        /* create the new one */
-        add_child(parent, chain, syms);
+        /* split the hits */
+        new->hit = parent->hit;
+        new->val_nr = parent->val_nr - idx_local;
+        parent->val_nr = idx_local;
+
+        /* create a new child for the new branch if any */
+        if (idx_total < chain->nr) {
+                parent->hit = 0;
+                add_child(parent, chain, idx_total, syms);
+        } else {
+                parent->hit = 1;
+        }
 }
 
 static int
 __append_chain(struct callchain_node *root, struct ip_callchain *chain,
                int start, struct symbol **syms);
 
-static int
+static void
 __append_chain_children(struct callchain_node *root, struct ip_callchain *chain,
-                        struct symbol **syms)
+                        struct symbol **syms, int start)
 {
         struct callchain_node *rnode;
 
         /* lookup in childrens */
         list_for_each_entry(rnode, &root->children, brothers) {
-                int ret = __append_chain(rnode, chain, root->val_nr, syms);
+                int ret = __append_chain(rnode, chain, start, syms);
                 if (!ret)
-                        return 0;
+                        return;
         }
-        return -1;
+        /* nothing in children, add to the current node */
+        add_child(root, chain, start, syms);
 }
 
 static int
@@ -142,14 +190,22 @@ __append_chain(struct callchain_node *root, struct ip_callchain *chain,
         int i = start;
         bool found = false;
 
-        /* lookup in the current node */
+        /*
+         * Lookup in the current node
+         * If we have a symbol, then compare the start to match
+         * anywhere inside a function.
+         */
         list_for_each_entry(cnode, &root->val, list) {
-                if (cnode->ip != chain->ips[i++])
+                if (i == chain->nr)
+                        break;
+                if (cnode->sym && syms[i]) {
+                        if (cnode->sym->start != syms[i]->start)
+                                break;
+                } else if (cnode->ip != chain->ips[i])
                         break;
                 if (!found)
                         found = true;
-                if (i == chain->nr)
-                        break;
+                i++;
         }
 
         /* matches not, relay on the parent */
@@ -157,23 +213,25 @@ __append_chain(struct callchain_node *root, struct ip_callchain *chain,
                 return -1;
 
         /* we match only a part of the node. Split it and add the new chain */
-        if (i < root->val_nr) {
-                split_add_child(root, chain, cnode, i, syms);
+        if (i - start < root->val_nr) {
+                split_add_child(root, chain, cnode, start, i - start, syms);
                 return 0;
         }
 
         /* we match 100% of the path, increment the hit */
-        if (i == root->val_nr) {
+        if (i - start == root->val_nr && i == chain->nr) {
                 root->hit++;
                 return 0;
         }
 
-        return __append_chain_children(root, chain, syms);
+        /* We match the node and still have a part remaining */
+        __append_chain_children(root, chain, syms, i);
+
+        return 0;
 }
 
 void append_chain(struct callchain_node *root, struct ip_callchain *chain,
                   struct symbol **syms)
 {
-        if (__append_chain_children(root, chain, syms) == -1)
-                add_child(root, chain, syms);
+        __append_chain_children(root, chain, syms, 0);
 }