tools/perf/util/callchain.c

   1 /*
   2  * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
   3  *
   4  * Handle the callchains from the stream in an ad-hoc radix tree and then
   5  * sort them in an rbtree.
   6  *
   7  * Using a radix for code path provides a fast retrieval and factorizes
   8  * memory use. Also that lets us use the paths in a hierarchical graph view.
   9  *
  10  */
  11
  12 #include <stdlib.h>
  13 #include <stdio.h>
  14 #include <stdbool.h>
  15 #include <errno.h>
  16
  17 #include "callchain.h"
  18
  19
  20 static void
  21 rb_insert_callchain(struct rb_root *root, struct callchain_node *chain)
  22 {
  23         struct rb_node **p = &root->rb_node;
  24         struct rb_node *parent = NULL;
  25         struct callchain_node *rnode;
  26
  27         while (*p) {
  28                 parent = *p;
  29                 rnode = rb_entry(parent, struct callchain_node, rb_node);
  30
  31                 if (rnode->hit < chain->hit)
  32                         p = &(*p)->rb_left;
  33                 else
  34                         p = &(*p)->rb_right;
  35         }
  36
  37         rb_link_node(&chain->rb_node, parent, p);
  38         rb_insert_color(&chain->rb_node, root);
  39 }
  40
  41 /*
  42  * Once we get every callchains from the stream, we can now
  43  * sort them by hit
  44  */
  45 void sort_chain_to_rbtree(struct rb_root *rb_root, struct callchain_node *node)
  46 {
  47         struct callchain_node *child;
  48
  49         list_for_each_entry(child, &node->children, brothers)
  50                 sort_chain_to_rbtree(rb_root, child);
  51
  52         if (node->hit)
  53                 rb_insert_callchain(rb_root, node);
  54 }
  55
  56 /*
  57  * Create a child for a parent. If inherit_children, then the new child
  58  * will become the new parent of it's parent children
  59  */
  60 static struct callchain_node *
  61 create_child(struct callchain_node *parent, bool inherit_children)
  62 {
  63         struct callchain_node *new;
  64
  65         new = malloc(sizeof(*new));
  66         if (!new) {
  67                 perror("not enough memory to create child for code path tree");
  68                 return NULL;
  69         }
  70         new->parent = parent;
  71         INIT_LIST_HEAD(&new->children);
  72         INIT_LIST_HEAD(&new->val);
  73
  74         if (inherit_children) {
  75                 struct callchain_node *next;
  76
  77                 list_splice(&parent->children, &new->children);
  78                 INIT_LIST_HEAD(&parent->children);
  79
  80                 list_for_each_entry(next, &new->children, brothers)
  81                         next->parent = new;
  82         }
  83         list_add_tail(&new->brothers, &parent->children);
  84
  85         return new;
  86 }
  87
  88 /*
  89  * Fill the node with callchain values
  90  */
  91 static void
  92 fill_node(struct callchain_node *node, struct ip_callchain *chain,
  93           int start, struct symbol **syms)
  94 {
  95         unsigned int i;
  96
  97         for (i = start; i < chain->nr; i++) {
  98                 struct callchain_list *call;
  99
 100                 call = malloc(sizeof(*call));
 101                 if (!call) {
 102                         perror("not enough memory for the code path tree");
 103                         return;
 104                 }
 105                 call->ip = chain->ips[i];
 106                 call->sym = syms[i];
 107                 list_add_tail(&call->list, &node->val);
 108         }
 109         node->val_nr = chain->nr - start;
 110         if (!node->val_nr)
 111                 printf("Warning: empty node in callchain tree\n");
 112 }
 113
 114 static void
 115 add_child(struct callchain_node *parent, struct ip_callchain *chain,
 116           int start, struct symbol **syms)
 117 {
 118         struct callchain_node *new;
 119
 120         new = create_child(parent, false);
 121         fill_node(new, chain, start, syms);
 122
 123         new->hit = 1;
 124 }
 125
 126 /*
 127  * Split the parent in two parts (a new child is created) and
 128  * give a part of its callchain to the created child.
 129  * Then create another child to host the given callchain of new branch
 130  */
 131 static void
 132 split_add_child(struct callchain_node *parent, struct ip_callchain *chain,
 133                 struct callchain_list *to_split, int idx_parents, int idx_local,
 134                 struct symbol **syms)
 135 {
 136         struct callchain_node *new;
 137         struct list_head *old_tail;
 138         unsigned int idx_total = idx_parents + idx_local;
 139
 140         /* split */
 141         new = create_child(parent, true);
 142
 143         /* split the callchain and move a part to the new child */
 144         old_tail = parent->val.prev;
 145         list_del_range(&to_split->list, old_tail);
 146         new->val.next = &to_split->list;
 147         new->val.prev = old_tail;
 148         to_split->list.prev = &new->val;
 149         old_tail->next = &new->val;
 150
 151         /* split the hits */
 152         new->hit = parent->hit;
 153         new->val_nr = parent->val_nr - idx_local;
 154         parent->val_nr = idx_local;
 155
 156         /* create a new child for the new branch if any */
 157         if (idx_total < chain->nr) {
 158                 parent->hit = 0;
 159                 add_child(parent, chain, idx_total, syms);
 160         } else {
 161                 parent->hit = 1;
 162         }
 163 }
 164
 165 static int
 166 __append_chain(struct callchain_node *root, struct ip_callchain *chain,
 167                unsigned int start, struct symbol **syms);
 168
 169 static void
 170 __append_chain_children(struct callchain_node *root, struct ip_callchain *chain,
 171                         struct symbol **syms, unsigned int start)
 172 {
 173         struct callchain_node *rnode;
 174
 175         /* lookup in childrens */
 176         list_for_each_entry(rnode, &root->children, brothers) {
 177                 unsigned int ret = __append_chain(rnode, chain, start, syms);
 178
 179                 if (!ret)
 180                         return;
 181         }
 182         /* nothing in children, add to the current node */
 183         add_child(root, chain, start, syms);
 184 }
 185
 186 static int
 187 __append_chain(struct callchain_node *root, struct ip_callchain *chain,
 188                unsigned int start, struct symbol **syms)
 189 {
 190         struct callchain_list *cnode;
 191         unsigned int i = start;
 192         bool found = false;
 193
 194         /*
 195          * Lookup in the current node
 196          * If we have a symbol, then compare the start to match
 197          * anywhere inside a function.
 198          */
 199         list_for_each_entry(cnode, &root->val, list) {
 200                 if (i == chain->nr)
 201                         break;
 202                 if (cnode->sym && syms[i]) {
 203                         if (cnode->sym->start != syms[i]->start)
 204                                 break;
 205                 } else if (cnode->ip != chain->ips[i])
 206                         break;
 207                 if (!found)
 208                         found = true;
 209                 i++;
 210         }
 211
 212         /* matches not, relay on the parent */
 213         if (!found)
 214                 return -1;
 215
 216         /* we match only a part of the node. Split it and add the new chain */
 217         if (i - start < root->val_nr) {
 218                 split_add_child(root, chain, cnode, start, i - start, syms);
 219                 return 0;
 220         }
 221
 222         /* we match 100% of the path, increment the hit */
 223         if (i - start == root->val_nr && i == chain->nr) {
 224                 root->hit++;
 225                 return 0;
 226         }
 227
 228         /* We match the node and still have a part remaining */
 229         __append_chain_children(root, chain, syms, i);
 230
 231         return 0;
 232 }
 233
 234 void append_chain(struct callchain_node *root, struct ip_callchain *chain,
 235                   struct symbol **syms)
 236 {
 237         __append_chain_children(root, chain, syms, 0);
 238 }