1 /*
2 * Copyright (C) 2009-2011, 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 #include <math.h>
17
18 #include "util.h"
19 #include "callchain.h"
20
ip_callchain__valid(struct ip_callchain * chain,const union perf_event * event)21 bool ip_callchain__valid(struct ip_callchain *chain,
22 const union perf_event *event)
23 {
24 unsigned int chain_size = event->header.size;
25 chain_size -= (unsigned long)&event->ip.__more_data - (unsigned long)event;
26 return chain->nr * sizeof(u64) <= chain_size;
27 }
28
29 #define chain_for_each_child(child, parent) \
30 list_for_each_entry(child, &parent->children, siblings)
31
32 #define chain_for_each_child_safe(child, next, parent) \
33 list_for_each_entry_safe(child, next, &parent->children, siblings)
34
35 static void
rb_insert_callchain(struct rb_root * root,struct callchain_node * chain,enum chain_mode mode)36 rb_insert_callchain(struct rb_root *root, struct callchain_node *chain,
37 enum chain_mode mode)
38 {
39 struct rb_node **p = &root->rb_node;
40 struct rb_node *parent = NULL;
41 struct callchain_node *rnode;
42 u64 chain_cumul = callchain_cumul_hits(chain);
43
44 while (*p) {
45 u64 rnode_cumul;
46
47 parent = *p;
48 rnode = rb_entry(parent, struct callchain_node, rb_node);
49 rnode_cumul = callchain_cumul_hits(rnode);
50
51 switch (mode) {
52 case CHAIN_FLAT:
53 if (rnode->hit < chain->hit)
54 p = &(*p)->rb_left;
55 else
56 p = &(*p)->rb_right;
57 break;
58 case CHAIN_GRAPH_ABS: /* Falldown */
59 case CHAIN_GRAPH_REL:
60 if (rnode_cumul < chain_cumul)
61 p = &(*p)->rb_left;
62 else
63 p = &(*p)->rb_right;
64 break;
65 case CHAIN_NONE:
66 default:
67 break;
68 }
69 }
70
71 rb_link_node(&chain->rb_node, parent, p);
72 rb_insert_color(&chain->rb_node, root);
73 }
74
75 static void
__sort_chain_flat(struct rb_root * rb_root,struct callchain_node * node,u64 min_hit)76 __sort_chain_flat(struct rb_root *rb_root, struct callchain_node *node,
77 u64 min_hit)
78 {
79 struct callchain_node *child;
80
81 chain_for_each_child(child, node)
82 __sort_chain_flat(rb_root, child, min_hit);
83
84 if (node->hit && node->hit >= min_hit)
85 rb_insert_callchain(rb_root, node, CHAIN_FLAT);
86 }
87
88 /*
89 * Once we get every callchains from the stream, we can now
90 * sort them by hit
91 */
92 static void
sort_chain_flat(struct rb_root * rb_root,struct callchain_root * root,u64 min_hit,struct callchain_param * param __used)93 sort_chain_flat(struct rb_root *rb_root, struct callchain_root *root,
94 u64 min_hit, struct callchain_param *param __used)
95 {
96 __sort_chain_flat(rb_root, &root->node, min_hit);
97 }
98
__sort_chain_graph_abs(struct callchain_node * node,u64 min_hit)99 static void __sort_chain_graph_abs(struct callchain_node *node,
100 u64 min_hit)
101 {
102 struct callchain_node *child;
103
104 node->rb_root = RB_ROOT;
105
106 chain_for_each_child(child, node) {
107 __sort_chain_graph_abs(child, min_hit);
108 if (callchain_cumul_hits(child) >= min_hit)
109 rb_insert_callchain(&node->rb_root, child,
110 CHAIN_GRAPH_ABS);
111 }
112 }
113
114 static void
sort_chain_graph_abs(struct rb_root * rb_root,struct callchain_root * chain_root,u64 min_hit,struct callchain_param * param __used)115 sort_chain_graph_abs(struct rb_root *rb_root, struct callchain_root *chain_root,
116 u64 min_hit, struct callchain_param *param __used)
117 {
118 __sort_chain_graph_abs(&chain_root->node, min_hit);
119 rb_root->rb_node = chain_root->node.rb_root.rb_node;
120 }
121
__sort_chain_graph_rel(struct callchain_node * node,double min_percent)122 static void __sort_chain_graph_rel(struct callchain_node *node,
123 double min_percent)
124 {
125 struct callchain_node *child;
126 u64 min_hit;
127
128 node->rb_root = RB_ROOT;
129 min_hit = ceil(node->children_hit * min_percent);
130
131 chain_for_each_child(child, node) {
132 __sort_chain_graph_rel(child, min_percent);
133 if (callchain_cumul_hits(child) >= min_hit)
134 rb_insert_callchain(&node->rb_root, child,
135 CHAIN_GRAPH_REL);
136 }
137 }
138
139 static void
sort_chain_graph_rel(struct rb_root * rb_root,struct callchain_root * chain_root,u64 min_hit __used,struct callchain_param * param)140 sort_chain_graph_rel(struct rb_root *rb_root, struct callchain_root *chain_root,
141 u64 min_hit __used, struct callchain_param *param)
142 {
143 __sort_chain_graph_rel(&chain_root->node, param->min_percent / 100.0);
144 rb_root->rb_node = chain_root->node.rb_root.rb_node;
145 }
146
callchain_register_param(struct callchain_param * param)147 int callchain_register_param(struct callchain_param *param)
148 {
149 switch (param->mode) {
150 case CHAIN_GRAPH_ABS:
151 param->sort = sort_chain_graph_abs;
152 break;
153 case CHAIN_GRAPH_REL:
154 param->sort = sort_chain_graph_rel;
155 break;
156 case CHAIN_FLAT:
157 param->sort = sort_chain_flat;
158 break;
159 case CHAIN_NONE:
160 default:
161 return -1;
162 }
163 return 0;
164 }
165
166 /*
167 * Create a child for a parent. If inherit_children, then the new child
168 * will become the new parent of it's parent children
169 */
170 static struct callchain_node *
create_child(struct callchain_node * parent,bool inherit_children)171 create_child(struct callchain_node *parent, bool inherit_children)
172 {
173 struct callchain_node *new;
174
175 new = zalloc(sizeof(*new));
176 if (!new) {
177 perror("not enough memory to create child for code path tree");
178 return NULL;
179 }
180 new->parent = parent;
181 INIT_LIST_HEAD(&new->children);
182 INIT_LIST_HEAD(&new->val);
183
184 if (inherit_children) {
185 struct callchain_node *next;
186
187 list_splice(&parent->children, &new->children);
188 INIT_LIST_HEAD(&parent->children);
189
190 chain_for_each_child(next, new)
191 next->parent = new;
192 }
193 list_add_tail(&new->siblings, &parent->children);
194
195 return new;
196 }
197
198
199 /*
200 * Fill the node with callchain values
201 */
202 static void
fill_node(struct callchain_node * node,struct callchain_cursor * cursor)203 fill_node(struct callchain_node *node, struct callchain_cursor *cursor)
204 {
205 struct callchain_cursor_node *cursor_node;
206
207 node->val_nr = cursor->nr - cursor->pos;
208 if (!node->val_nr)
209 pr_warning("Warning: empty node in callchain tree\n");
210
211 cursor_node = callchain_cursor_current(cursor);
212
213 while (cursor_node) {
214 struct callchain_list *call;
215
216 call = zalloc(sizeof(*call));
217 if (!call) {
218 perror("not enough memory for the code path tree");
219 return;
220 }
221 call->ip = cursor_node->ip;
222 call->ms.sym = cursor_node->sym;
223 call->ms.map = cursor_node->map;
224 list_add_tail(&call->list, &node->val);
225
226 callchain_cursor_advance(cursor);
227 cursor_node = callchain_cursor_current(cursor);
228 }
229 }
230
231 static void
add_child(struct callchain_node * parent,struct callchain_cursor * cursor,u64 period)232 add_child(struct callchain_node *parent,
233 struct callchain_cursor *cursor,
234 u64 period)
235 {
236 struct callchain_node *new;
237
238 new = create_child(parent, false);
239 fill_node(new, cursor);
240
241 new->children_hit = 0;
242 new->hit = period;
243 }
244
245 /*
246 * Split the parent in two parts (a new child is created) and
247 * give a part of its callchain to the created child.
248 * Then create another child to host the given callchain of new branch
249 */
250 static void
split_add_child(struct callchain_node * parent,struct callchain_cursor * cursor,struct callchain_list * to_split,u64 idx_parents,u64 idx_local,u64 period)251 split_add_child(struct callchain_node *parent,
252 struct callchain_cursor *cursor,
253 struct callchain_list *to_split,
254 u64 idx_parents, u64 idx_local, u64 period)
255 {
256 struct callchain_node *new;
257 struct list_head *old_tail;
258 unsigned int idx_total = idx_parents + idx_local;
259
260 /* split */
261 new = create_child(parent, true);
262
263 /* split the callchain and move a part to the new child */
264 old_tail = parent->val.prev;
265 list_del_range(&to_split->list, old_tail);
266 new->val.next = &to_split->list;
267 new->val.prev = old_tail;
268 to_split->list.prev = &new->val;
269 old_tail->next = &new->val;
270
271 /* split the hits */
272 new->hit = parent->hit;
273 new->children_hit = parent->children_hit;
274 parent->children_hit = callchain_cumul_hits(new);
275 new->val_nr = parent->val_nr - idx_local;
276 parent->val_nr = idx_local;
277
278 /* create a new child for the new branch if any */
279 if (idx_total < cursor->nr) {
280 parent->hit = 0;
281 add_child(parent, cursor, period);
282 parent->children_hit += period;
283 } else {
284 parent->hit = period;
285 }
286 }
287
288 static int
289 append_chain(struct callchain_node *root,
290 struct callchain_cursor *cursor,
291 u64 period);
292
293 static void
append_chain_children(struct callchain_node * root,struct callchain_cursor * cursor,u64 period)294 append_chain_children(struct callchain_node *root,
295 struct callchain_cursor *cursor,
296 u64 period)
297 {
298 struct callchain_node *rnode;
299
300 /* lookup in childrens */
301 chain_for_each_child(rnode, root) {
302 unsigned int ret = append_chain(rnode, cursor, period);
303
304 if (!ret)
305 goto inc_children_hit;
306 }
307 /* nothing in children, add to the current node */
308 add_child(root, cursor, period);
309
310 inc_children_hit:
311 root->children_hit += period;
312 }
313
314 static int
append_chain(struct callchain_node * root,struct callchain_cursor * cursor,u64 period)315 append_chain(struct callchain_node *root,
316 struct callchain_cursor *cursor,
317 u64 period)
318 {
319 struct callchain_cursor_node *curr_snap = cursor->curr;
320 struct callchain_list *cnode;
321 u64 start = cursor->pos;
322 bool found = false;
323 u64 matches;
324
325 /*
326 * Lookup in the current node
327 * If we have a symbol, then compare the start to match
328 * anywhere inside a function.
329 */
330 list_for_each_entry(cnode, &root->val, list) {
331 struct callchain_cursor_node *node;
332 struct symbol *sym;
333
334 node = callchain_cursor_current(cursor);
335 if (!node)
336 break;
337
338 sym = node->sym;
339
340 if (cnode->ms.sym && sym) {
341 if (cnode->ms.sym->start != sym->start)
342 break;
343 } else if (cnode->ip != node->ip)
344 break;
345
346 if (!found)
347 found = true;
348
349 callchain_cursor_advance(cursor);
350 }
351
352 /* matches not, relay on the parent */
353 if (!found) {
354 cursor->curr = curr_snap;
355 cursor->pos = start;
356 return -1;
357 }
358
359 matches = cursor->pos - start;
360
361 /* we match only a part of the node. Split it and add the new chain */
362 if (matches < root->val_nr) {
363 split_add_child(root, cursor, cnode, start, matches, period);
364 return 0;
365 }
366
367 /* we match 100% of the path, increment the hit */
368 if (matches == root->val_nr && cursor->pos == cursor->nr) {
369 root->hit += period;
370 return 0;
371 }
372
373 /* We match the node and still have a part remaining */
374 append_chain_children(root, cursor, period);
375
376 return 0;
377 }
378
callchain_append(struct callchain_root * root,struct callchain_cursor * cursor,u64 period)379 int callchain_append(struct callchain_root *root,
380 struct callchain_cursor *cursor,
381 u64 period)
382 {
383 if (!cursor->nr)
384 return 0;
385
386 callchain_cursor_commit(cursor);
387
388 append_chain_children(&root->node, cursor, period);
389
390 if (cursor->nr > root->max_depth)
391 root->max_depth = cursor->nr;
392
393 return 0;
394 }
395
396 static int
merge_chain_branch(struct callchain_cursor * cursor,struct callchain_node * dst,struct callchain_node * src)397 merge_chain_branch(struct callchain_cursor *cursor,
398 struct callchain_node *dst, struct callchain_node *src)
399 {
400 struct callchain_cursor_node **old_last = cursor->last;
401 struct callchain_node *child, *next_child;
402 struct callchain_list *list, *next_list;
403 int old_pos = cursor->nr;
404 int err = 0;
405
406 list_for_each_entry_safe(list, next_list, &src->val, list) {
407 callchain_cursor_append(cursor, list->ip,
408 list->ms.map, list->ms.sym);
409 list_del(&list->list);
410 free(list);
411 }
412
413 if (src->hit) {
414 callchain_cursor_commit(cursor);
415 append_chain_children(dst, cursor, src->hit);
416 }
417
418 chain_for_each_child_safe(child, next_child, src) {
419 err = merge_chain_branch(cursor, dst, child);
420 if (err)
421 break;
422
423 list_del(&child->siblings);
424 free(child);
425 }
426
427 cursor->nr = old_pos;
428 cursor->last = old_last;
429
430 return err;
431 }
432
callchain_merge(struct callchain_cursor * cursor,struct callchain_root * dst,struct callchain_root * src)433 int callchain_merge(struct callchain_cursor *cursor,
434 struct callchain_root *dst, struct callchain_root *src)
435 {
436 return merge_chain_branch(cursor, &dst->node, &src->node);
437 }
438
callchain_cursor_append(struct callchain_cursor * cursor,u64 ip,struct map * map,struct symbol * sym)439 int callchain_cursor_append(struct callchain_cursor *cursor,
440 u64 ip, struct map *map, struct symbol *sym)
441 {
442 struct callchain_cursor_node *node = *cursor->last;
443
444 if (!node) {
445 node = calloc(sizeof(*node), 1);
446 if (!node)
447 return -ENOMEM;
448
449 *cursor->last = node;
450 }
451
452 node->ip = ip;
453 node->map = map;
454 node->sym = sym;
455
456 cursor->nr++;
457
458 cursor->last = &node->next;
459
460 return 0;
461 }
462